New Zealand is a small country in the South Pacific Ocean, located 1200 miles southeast of Australia. It consists of two main islands, called the North Island and the South Island. Auckland, the largest city, is located on the North Island. Christchurch, the second largest city, is located on the South Island. Wellington, the capital and third largest city, is on the southern tip of the North Island – a good central location for the country as a whole. I visited all 3 of these cities, along with journeys by train, bus, ferry, and car through various rural areas and small towns.

The entire country has around 4.3 million people – not a lot of people. The US state of Colorado is a close match to New Zealand both in terms of total land area and total population. The climate is generally cool and rainy, but the local climate can vary considerably from one place to another. Most parts of the country are either hilly or mountainous, but there are some flat areas, the largest being the Canterbury Plains on the east side of the South Island.

For people outside of Australia and New Zealand, the two countries appear to be closely related siblings – much like the US and Canada are similar to each other. In fact, this impression is largely true – the two countries have a lot in common, including a shared language, a similar colonial history, and very close trade and political ties. For me, therefore, my most interesting discoveries were the details that set New Zealand apart from Australia – the things that make New Zealand unique.

During my 12 weeks in Australia, prior to visiting New Zealand, it seemed to me that the relationship between the two countries was about as close as two countries could get. Residents of New Zealand have to the right to live and work in Australia without obtaining a visa – and vice versa. As a result, lots of New Zealanders do in fact live in Australia. Australia is the leading export market for New Zealand products. New Zealand attended the constitutional conventions that resulted in the combining of 6 distinct British colonies into a new entity called Australia in 1901. However, New Zealand chose not to join the new union.

I gained a new perspective on the relationship between the two countries during my 4 weeks in New Zealand. I saw that New Zealanders (or “kiwis” as they like to call themselves) are almost desperate to distinguish themselves from Australia, to step out from the shadow of their larger neighbor – despite the close and friendly ties. You’ll often hear New Zealanders make subtle digs at Australia, while I seldom if ever heard Australians making digs at New Zealand. This reminds me a lot of the relationship between Canada and the US, and the efforts that Canadians make to distinguish themselves from the US.

For me, there were 6 differences between New Zealand and Australia that most impressed me:

1. Differences in the pre-European inhabitants of the two countries

2. Differences in the native plants and animals

3. Differences in the geology and geologic history

4. Differences in the economies, particularly the export products

5. Differences in the landscapes

6. Differences in government land ownership

There were two other attributes that particularly caught my attention:

7. Details regarding New Zealand’s largest cities

8. The large number of immigrants living in both New Zealand and Australia

So here are my thoughts on the above 8 topics:

1. Pre-European Inhabitants

Despite the relatively close proximity of Australia and New Zealand, the two countries are extraordinarily different in terms of their pre-European inhabitants. Australia has been inhabited for tens of thousands of years by aboriginal people who were part of a long-ago human migration from Africa, eastward along the south coast of Asia, and on to New Guinea and Australia via land bridges that existed during the ice ages. The people were primarily hunter-gatherers with a relatively simple material culture.

New Zealand has only been inhabited by humans for around 800 years. The pre-European inhabitants, known as Maori, are Polynesians who migrated long distances by boat from other Pacific Islands located far to the northeast of New Zealand. They had an agricultural society, and brought with them their familiar crops and domestic animals – although not all of the imported plants survived in the colder climate of New Zealand. As an agricultural society, the Maoris were able to support a greater population density than the Australian aborigines. This in turn led to a more developed material culture, along with a more hierarchical society. When the Europeans finally arrived, the Maoris were well-practiced in warfare and could offer a stronger resistance to the intrusion of the whites than the Australian aboriginals could.

Because the aboriginals and the Maori came from completely different parts of the world, they look quite difference and speak entirely unrelated languages. They have little in common, other than that they both arrived before the Europeans did – and that they had both became intimately familiar with the landscape and with the native plants and animals of their lands.

Today, Australian aborigines comprise only 2.6% of the Australian population, while Maoris constitute 15% of the New Zealand population. Furthermore, another 7% of the New Zealand population is composed of Pacific Islanders, whose ancestors migrated to New Zealand in the past century from other Pacific islands. The Pacific Islanders share a similar culture and language to the Maori. The upshot is that Maori and Pacific culture is a powerful force both politically and in forming the national identity of the New Zealand people. The Maori language is an official language of New Zealand, along with English, and most official signage is printed in both languages. You can tune to Maori-language broadcasts on television, including newscasters presenting the news in Maori. Maori themes and topics are ubiquitous in tourist gift shops and literature – far more than aboriginal themes and topics appear in gift shops in Australia.

Of course, Maoris and Pacific Islanders are not distributed evenly throughout New Zealand. I spent my first week in Auckland – where many of the Pacific Islanders live – and the second week in the central highlands of the North Island – where some of the towns have very large Maori populations. But in the South Island I encountered much less Maori influence. On the other hand, everywhere I went, the names of nearly every native plant and animal – especially trees and birds – were of Maori origin. In contrast, in Australia relatively few of the native plants and animals are commonly known by their aboriginal names.

Although the Maoris have not always been treated well by the “pakehas” (New Zealanders of European descent), the Maoris have usually gotten a much better deal than the aborigines of Australia. In particular, the Maoris received the right to vote in 1902, while the aborigines of Australia did not receive the right to vote until 1962 – about the same time as the Civil Rights movement in the US.

2. Native Plants and Animals

When we think of the native wildlife of Australia, most of us first think of kangaroos and koalas. When we think of New Zealand, we think of kiwi birds. But other than the presence of kiwi birds, I had expected the native plants and animals of New Zealand to have a lot in common with the native flora and fauna of Australia. I was quite surprised to find that this is not the case at all.

First of all, Australia is widely known for its wide range of marsupials – not just kangaroos and koalas, but also wallabies, possums, bandicoots, wombats, and so on. I had expected to see other unique marsupials in New Zealand. However, New Zealand has no native mammals at all, other than a few species of bats. None! As a result, birds, insects, and reptiles had evolved to fill the ecological niches that in most other places are filled by mammals. Many of these native animals are now rare or extinct, but it is still fascinating to ponder the many species of flightless birds that once lived in New Zealand, or to view the giant wetas – large insects related to crickets.

As for trees, the forests of Australia are best known for the 600 different species of eucalyptus. I had expected that the native forests of New Zealand would also contain many species of eucalyptus. Again, my expectations were completely wrong. There are no native eucalyptus species in New Zealand. Instead, the native forests are populated by trees that seemed quite different from most of the trees that I had learned or seen in Australia.

Finally, I had thought that I would see many interesting species of native wildflowers in New Zealand, just as I had done in Australia. In fact, I saw hardly any native wildflowers at all. Part of the issue is that I did not visit New Zealand at the correct time of year to see the wildflowers. But it also appears that New Zealand, unlike Australia, does not have such a wealth of wildflowers. In parts of the South Island, there is a great deal of publicity about the colorful wild lupines that bloom in the spring – but these are escaped garden flowers that are not native to New Zealand.

On the other hand, New Zealand has an amazing variety in its species of ferns. These range from very small ferns to giants that take the form of trees. Ferns dominant the understory of most forests, especially the tree ferns. The large number of species translates into a wide range of leaf forms. Second only to kiwi birds, ferns are considered emblematic of New Zealand, and consequently fern images are ubiquitous in New Zealand as logos and other graphic representations.

Speaking of kiwi birds, I was surprised to learn that there are 5 species of kiwis – not just one – and that four of the species are quite rare and extremely limited in their geographic ranges. The four rare species are native to the South Island, and are found only in small pockets on the relatively undisturbed west coast. The one species that is relatively common – the North Island Brown Kiwi – is found only on the North Island, and even this species is rarely seen.

3. Geology and Geologic History

Prior to my visit to New Zealand, I knew that the country sits along the Pacific Ring of Fire – a zone of earthquakes and volcanoes that surrounds the Pacific Ocean – while Australia does not. I also knew that the South Island is famous for its mountains. But otherwise I had not thought much about the geology of New Zealand, and I assumed by default that the geology must be somewhat similar to that of Australia. Therefore I was surprised to learn that the geology and geologic history of New Zealand are quite different from that of Australia – although there are some common elements, due to the fact that New Zealand was once attached to Australia.

Australia is an ancient continent – much of the land was created a very long time ago. As a result, there are extensive areas of Precambrian rock in Australia, while no Precambrian rock can be found in New Zealand at all. Many of the places that I have visited in eastern Australia are dominated by flat layers of sandstone deposits, including the Blue Mountains just to the west of Sydney. In contrast, much of the land in New Zealand’s North Island is of volcanic origin. The South Island includes large areas of marine deposts that have been metamorphosed and uplifted.

Because New Zealand sits along the Pacific Ring of Fire, I was not at all surprised that a plate boundary (between two tectonic plates) passes nearby. But I was quite surprised to learn that the plate boundary actually passes through the South Island, and that as a result, most of the South Island sits on a different plate than the does the North Island. The North Island sits on the Australian plate – the same plate that Australia sits on. Most of the South Island sits on the Pacific Plate – the same plate that Los Angeles sits on. (Note: Most of North America sits on the North American plate. But the coast of California southward from San Francisco – the land that is west of the San Andreas fault – sits on the Pacific plate.)

Even more surprising is that the boundary between the Pacific and Australian plates is moving in opposite directions in different parts of the boundary. Parallel to the east coast of the North Island, the Pacific plate dives westward beneath the Australian plate. The subducting Pacific plate melts as it slides beneath the North Island, resulting in ongoing volcanic activity in various parts of the North Island. South of the South Island, the Australian plate is sliding eastward beneath the Pacific plate. The crossover zone, where neither plate can slide beneath the other, is the mountainous region down the west side of the South Island – the New Zealand Alps. In this zone the two plates crush together in a transverse fault, uplifting the mountains.

The upshot is that the North Island is full of volcanic cones and geothermal activity, while the South Island has the highest mountains and the most serious earthquakes. I was quite surprised to learn that most of the hills in the city of Auckland are volcanic cinder cones. It was also interesting to see that while the beaches in Australia are full of white sand – quartz sand eroded from the sandstone and other rocks – the beaches in New Zealand are often black or gray, and often pebbly.

4. Economies and Exports

Because of the tight ties and similar history between Australia and New Zealand, I expected the two countries to have similar economies. But in many respects the two economies are quite different. Australia’s export economy depends to a large extent on mining, and the boom times in Australia right now are primarily due to the high demand in China for Australia’s mineral exports – such as iron ore and coal. Australia also has a noteworthy manufacturing sector. In contrast, New Zealand’s economy is primarily agricultural. Much of New Zealand’s land is dedicated to grazing. The resulting products include wool and dairy products, which are exported in large quantities. New Zealand also exports a lot of timber, the vast majority of which is Monterrey pine (Pinus radiata), a tree native to the west coast of California. New Zealand also exports various horticultural products, such as kiwi fruit and other fruits and vegetables. Fishing is also an important export industry. Supplementing these exports, tourism is also an important source of income for the country.

The upshot is that the economies of the two countries are quite different. Yet both countries are prosperous, with a high standard of living. The two economies are somewhat complementary, and as a result the two countries engage in a lot of trade with each other.

5. Differences in the Landscapes

Although much of Australia is desert or semi-desert, the lands near the East coast, where most of the people live, receive adequate amounts of rain all year – or in some cases (as in the recent Queensland floods) too much rain. Flat-topped mountains and plateaus, composed of flat layers of sandstone, rise up as you head inland from the coast. Outside of the population centers, most of the mountains and hills are covered by eucalyptus forests. Sheltered valleys often contain fern trees and other “rain forest” vegetation. (Australians refer to all of the moist forests as “rain forests”, regardless of the actual amount of rainfall.) Westward, beyond the eastern mountain ranges, the land becomes increasingly arid, first turning to grasslands, and finally to deserts. The grasslands of the eastern interior have largely been replaced by irrigated agriculture, similar to the Central Plains of the US.

New Zealand has a very different set of landscapes. Most of New Zealand is either mountainous or hilly – although the Canterbury Plain on the South Island is an important exception. The mountains of New Zealand tend to be steep and rugged, usually lacking the flat tops so common in Australia. The mountains in the South Island are also taller than the mountains of Australia. In its original, natural state, prior to the arrival of humans, 85% of New Zealand was covered by native forests. These forests were dense and quite green, in contrast to the more open and dryer eucalyptus forests of Australia. The remaining 15% of New Zealand consisted primarily of lands that were too high and cold for forest, but it also included places where the soil was too soggy to support forest.

When the Maoris arrived around 1300 AD, they began to cut and burn large areas of forest – to clear agricultural lands, to encourage the growth of bracken fern (an important food source), and to make use of the lumber. By the time Europeans arrived in the early 1800s, the native forest had shrunk from 85% to 55% of the land. The Europeans very quickly destroyed another 30 percentage points, reducing the native forest to just 25% of the land. Much of that 25% is located far from the population and agricultural centers. In the parts of the North Island that I passed through by train or bus, it seemed that far less than 25% of the land was in native forest. In the parts of the South Island that I passed through by train or automobile, native forest had been completely eliminated from at least 99% of the land. To my eyes, much of New Zealand looked like one huge ecological disaster. Instead of native forests, I saw miles and miles of land kept artificially in pasture by the grazing of sheep and cows. In those places where I did see forest, it was almost always in the form of non-native lumber plantations (mostly Monterrey pine) being grown for quick harvest and export.

However, I know that my sample does represent all of New Zealand, despite my traveling 2/3 of the length of the North Island, and half the length of the South Island. For one thing, except for a short stretch in the northeastern part of the South Island, I saw almost no lands dedicated to horticulture, and yet I know that New Zealand grows fruits and vegetables. And the very rainy and rugged West coast of the South Island is likely to be quite different from most of the lands that I saw.

Near the town of Rotorua in the North Island, there is a much-beloved forest that the local people call “the Redwood Forest”. The entire forest consists of non-native trees. The most spectacular section – and the part that is most visited – is a section of several acres planted entirely in California Redwoods. Many people recommended that I visit the Redwood Forest while I was in Rotorua – which of course I did. And indeed it was a very beautiful forest. But I would have liked to have seen a native forest that was equally loved.

The most spectacular landscapes I saw in New Zealand were on the South Island, as we drove inland from Christchurch to see the Southern Alps and the glacial lakes extending south and east from the Alps. We spent two days and nights in the region of Lake Tekapo, Lake Pukaki, and Mt. Cook – the highest mountain in New Zealand. During those days the western slopes of the Alps were covered by dense clouds and heavy rain. The eastern part of the island was mostly sunny and clear. As we approached Mt. Cook from the east, we transitioned in the last few miles from sunshine to light rain and clouds, and finally heavy rain. Mt. Cook was completely hidden by the clouds. Although the Hooker Valley, where we had planned to hike, was getting drenched with rain, the Tasman Valley a few miles away was receiving only light sprinkles. So we did our hiking in the Tasman Valley instead. (Both valleys contain glaciers, so we still got to see a glacier.) On the way back east, the strong winds from the west were blowing raindrops horizontally into areas where the sun was shining brightly. The result was a huge, non-stop rainbow that followed us for miles and miles as we drove.

6. Government Land Ownership

I definitely got the impression that the government in New Zealand is more hands-off than the government in Australia. There used to be several national forests in New Zealand, but these forests were sold off to private companies. There are no agricultural subsidies in New Zealand, but the agricultural sector seems to be doing fine without them. There are only a few national parks in the country, although some of these few are quite spectacular. I was surprised, for example, that despite the many examples of amazing geothermal activity in the North Island – and something found only in 3 countries in the world (the US, New Zealand, and Iceland) – I could not find a national park equivalent to Yellowstone in the US. Most of the best examples of geothermal activity (geysers, etc.) are in private parks. It is far too pricey to visit more than about two of these private parks, so you have to decide which one or two to visit, out of the many that seek your business. I should hasten to point out that some of these private parks are in Maori hands, and there are cultural, historical, and political reasons for leaving them that way. Still, I was quite surprised that there is no geothermal national park.

In contrast, I am amazed and delighted at the many beautiful national parks that are within a relatively short drive of Sydney, Australia. Not only are these parks quite beautiful, but they make it fairly easy to see diverse examples of native forest.

7. New Zealand’s Largest Cities

I spent time in each of New Zealand’s three largest cities – Auckland, Christchurch, and Wellington. None of the cities is very large by US or Australian standards. I like the resulting “small city” feel – fairly quiet, relatively easy to get around, and not very far to any destination in the city.

Auckland, the largest city in New Zealand, occupies a narrow isthmus on the North Island, and as a result the city spans across the island from the East coast to the West coast – a distance of about 10 miles. The downtown overlooks a harbor on the East coast, and includes the Sky Tower – the tallest building in the southern hemisphere. There are lots of students in the city, many of them visiting from Asia. Auckland also has more Pacific Islanders in its population than any other city in the world. The city is quite hilly, and most of the hills originated as volcanic cinder cones.

Christchurch, the second largest city, sits on a flat plain on the East coast of the South Island, but only a short drive to the towering Southern Alps. The city is often described as “the most English of New Zealand’s cities”, and the description fits. The placid Avon River – really just a large stream – winds through the town, and “punt boats” glide up and down the river through the botanical garden. These boats, popular with tourists, are driven by human power – the operator uses a pole to push against the river bottom. At present, the city sidewalks are an obstacle course because of the recent earthquakes. Fences block off the sidewalks in front of all of the damaged buildings, to prevent falling bricks from landing on anyone’s head. Still it is a charming town to visit.

Wellington, the nation’s capital and third largest city, sits on the southern tip of the North Island. The downtown area occupies a tiny strip of land between the harbor and an area of tall, steeply rising hills. It is a dramatic and beautiful setting for a city, and it is this city that most captured my interest. The hills behind the city center remind me of the Oakland and Berkeley hills – and in fact many things about the city reminded me of San Francisco. This impression was reinforced by all the Monterey Cypress trees growing on the hillsides, along with the Monterey Pines. I stayed in Wellington for a full week and went on very long walks almost every day, exploring in many different directions from the downtown.

8. Immigrants in New Zealand and Australia

In both Australia and New Zealand, nearly a quarter of the population is foreign born – an amazingly high percentage. This is double the percentage in the US, where only 1/8 of the population is foreign born. The largest source of immigrants for both countries is Great Britain, and another major source is each other – New Zealanders in Australia and Australians in New Zealand. However, it the Asian immigrants, particularly the Chinese, that are the most obvious, especially in the central business districts of any large city. Already there is a generation of young people growing up with Asian faces and Australian or New Zealand accents.

Both Australia and New Zealand have a low population density. Australia is nearly the same size as the continental US, and yet has only 1/10 as many people. The policy in both countries is that economic growth will require population growth, and therefore the immigration of young people with important skills should be encouraged. In Australia, the state of Western Australia is especially eager to grow its population through immigration. That said, neither country wants to throw its borders wide open – they want to be somewhat selective as to who gets in. And among the general population there are a few ripples of anti-immigrant sentiment, and as a result the governments of both countries have to take a balanced approach to immigration.

Concluding Details

My visit to New Zealand left me with a few additional impressions:

1) Black appears to be national color in New Zealand – despite the predominantly blue national flag (which, by the way, is nearly identical to the national flag of Australia). Most of the athletic wear I saw in New Zealand was black – black T-shirts, black running shorts, black socks, black tank tops, etc. As I walked around Wellington on a warm day, nearly all of the “kiwis” appeared to wearing black summer wear of one sort or another. In Melbourne, Australia, I also saw a lot of black clothing, but that was business wear and winter coats. In the US, most summer wear tends to be either white or brightly colored. So this was quite an interesting phenomenon to me.

2) New Zealanders have a different accent than Australians – although I would be hard pressed to identify the precise differences. The New Zealand accent seems gentler to me, and I liked hearing it. I was surprised at how often I encountered specific references to the New Zealand accent – including two shows on television musing on questions of national identity.

3) Many, many places in New Zealand are exceedingly proud that one scene or another in the Lord of the Rings trilogy was filmed at some nearby location. I kept encountering references to the films in tourist literature, on television, and even on signs in city parks. New Zealanders are well aware that most foreigners know nothing whatsoever about their country – except that the Lord of the Rings was filmed there. If this is all that many foreigners know about New Zealand, then you’ve got to milk it for all it’s worth!

Question: Name all the continents in the world, and point out each one on a globe.

As with the previous two questions – dealing with planets and human senses – this question assumes the existence of a specific class, in this case “continents”. Furthermore, the question assumes that the class contains only a small number of items, and that we can therefore memorize the entire list.

In light of our previous two examples, perhaps by now you are detecting a certain weakness in this kind of learning. On the one hand, simple classification models are essential to promote additional learning. Each model that we learn provides a framework upon which we can hang additional information. And it certainly can be helpful to memorize the entire list for small classes such as planets, human senses, and continents. But each class is (or should be) based on a set of clear criteria for distinguishing what items are in the class and what items are not in the class. If we simply memorize the list of items in a class, we run the risk that we won’t really understand the criteria upon which the class is based.

When I was a kid in elementary school, there was usually only one “right” answer to this question – what are the continents of the world? The expected answer was (usually) that there are 7 continents – North America, South America, Europe, Asia, Africa, Australia, and Antarctica. However, as an adult, when I met people who were educated in other parts of the world, I sometimes found that they were taught a different model, with a slightly different list of continents. In fact, I have encountered several variations on the model, and therefore several different lists of continents. How could this be? Is there a genuine “right” answer? What are the criteria for determining the right answer?

Even as a school kid, I could see that there were flaws in the model. On our tests we were expected to be able to provide a definition for the term “continent”, but the definition (which seemed to be different in each year’s textbook) never quite matched up with the list of continents. The most logical definition I encountered as a kid was “a large, contiguous landmass surrounded by water”. By this definition, Australia and Antarctica certainly qualified. But this definition had two big problems:

1) Five of the seven continents (North America, South America, Europe, Asia, and Africa) are not completely surrounded by water, but are in contact with other continents. Therefore I saw these not as five continents, but as two – the Americas, and Eurasia-Africa.

2) The word “large” is too vague to be useful. What is the threshold that distinguishes a “large landmass” from one that is not large? It seemed to me as a kid that Greenland was quite large, and therefore ought to be considered a continent.

Also, it seemed to me as a kid that the definition for “continent” and the definition for “island” were essentially identical, except for the size criterion. Therefore, it would make sense to create a single clear criterion that separated “large” from “not large”, and to use this one criterion to distinguish between continents and islands. Consequently, it would drive me up the wall to hear statements like “Australia is the world’s smallest continent and also the world’s largest island.” Why is Australia considered to be an island, but Antarctica is not? What is the criterion that distinguishes a large island from a landmass that is too large to be an island? I never found a teacher or a book that could answer these questions to my satisfaction. As far as I was concerned, if Australia is a continent, then it cannot be an island – no matter what answer was expected on the test at school. Why should these two categories (continents and islands) overlap – with a single item in common between the two classes – when it would be so much cleaner to use a single criterion to separate the two classes?

Of course, the above rationale is based on the assumption that the terms “continent” and “island” share a single definition, distinguished only by the criterion of size. But another definition for continent, slightly different than the previous one, is this:

continent – a very large, contiguous landmass surrounded or nearly surrounded by seawater

There are 3 subtle differences between this definition and the previous one:

1) “large” has been replaced by “very large”

2) “water” has been replaced by “seawater”

3) “surrounded” has been qualified as “surrounded or nearly surrounded”

The third change is the most profound. Even though the phrase “nearly surrounded” is not well defined, it seems clear that North America, South America, and Africa can all qualify as distinct continents under this definition. In each case, the only connection to another continent is via a narrow neck of land. However, Europe and Asia still cannot be separated under this model. Indeed, more than once (starting in middle school) I had a textbook that used a 6-continent model: North America, South America, Eurasia, Africa, Australia, and Antarctica.

Also note that these 3 changes to the definition of “continent” do not apply to the definition of “island”. An island must be surrounded by water – “nearly surrounded” is not good enough. (A small land mass that is “nearly surrounded” by water would be a peninsula.) Furthermore, the liquid surrounding a continent should be seawater, but for an island any kind of water will do. Therefore an island can be located in a lake or a river. (An island surrounded by seawater can be called a “sea island”.) Also note that an island located in a lake or river will be surrounded by a continent, or by a larger island. This leads to an interesting result. Even though our definition for “continent” includes the phrase “contiguous landmass”, we usually include any river or lake islands as part of the continent, even though they are not contiguous. In fact, we usually include the rivers and lakes as part of the continent too – and therefore the surface of the “continent” includes both land and water. This raises the question of whether we need to replace or enhance the phrase “contiguous landmass”.

From a practical standpoint, we typically go a step farther. If a sea island is separated from a continent by nothing more than a small channel, then we consider the island to be part of the continent. But now another vaguely defined idea has crept into the overall concept. How big can the “small channel” be before the island is no longer part of the continent? One practical way of solving this question is to see if the island is located on the continental shelf of the continent. If so, then the island can be considered to be part of the continent. (But when measuring the area of the continent, the continental shelf is not usually included.)

Our definition of “continent” is now beginning to look like this:

continent – a very large, contiguous landmass surrounded or nearly surrounded by seawater, along with any rivers and lakes located on the landmass, together with any islands located on the landmass or on the continental shelf

With this enhanced definition we still have only 6 continents – Europe and Asia remain combined into “Eurasia” – but at least we have a much clearer idea of what is included within any single continent. Still, the most popular model includes 7 continents, separating Europe and Asia into two continents. Furthermore, there are other models floating around out there. For example, one friend of mine who was educated in South America told me that she was taught in school that “Oceana” is a continent. This supposed continent includes all of the Pacific islands. Is there any way to modify our definition of “continent” to accommodate one or more of these other models?

One approach is to give up on creating a complete definition, and instead admit that the term “continent” refers to a culturally determined set of objects, rather than a set of objects defined by a common set of criteria. Personally I prefer to avoid this route. However, this was indeed the approach taken in Wikipedia, where the following definition is given: “A continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents – they are (from largest in size to smallest): Asia, Africa, North America, South America, Antarctica, Europe.” Although I think that the Wikipedia explanation is very well worded, it essentially says that the word “continent” cannot be defined. In fact, we have already created a definition, containing a clear set of criteria, which generates nearly the exact same set of continents. The only difference is that the traditional list of continents separates Eurasia into Europe and Asia – even though no such separation can be justified based on physical geography alone. Why are we so attached to distinguishing between two “continents” that are so – hmm – attached?

Part of the answer is that the Europe and Asia just seem so far apart. When we conjure up stereotypical pictures in our mind of “Europe”, we think of Western Europe. When we imagine stereotypical pictures of “Asia”, we think of Eastern Asia. There is indeed a large physical distance between these stereotypical locations, and perhaps an even greater cultural distance. Our minds rebel at incorporating so much diversity within the category of a single “continent”. Intuitively, we expect a certain homogeneity within a continent, so that we can assign a set of typical characteristics to it. It’s easy enough to come up with stereotypical concepts for any of the other continents – North America, South America, Africa, Australia, Antarctica – but it’s awfully hard to do this for “Eurasia”. And while our stereotypes are indeed drawn in part from physical geography – for example, Antarctica is icy while Africa is tropical – a very large part of our stereotyping is based on human cultural geography. We don’t distinguish between Europe and Asia based on climate or topography – we feel compelled to distinguish between them based on human and cultural differences.

So while our definitions for “continent” focus exclusively on factors related to physical geography, intuitively we rely to an equal extent – or perhaps an even greater extent – on our concepts of human and cultural geography to distinguish the continents. This phenomenon has several interesting side-effects, including the following two:

1) If you ask someone in the US to point out on a map or a globe where North America ends and South America begins, many people have a very hard time doing so. If you base it strictly on physical geography, it seems obvious that the dividing line ought to occur where the connection between the two continents is narrowest – in Panama. This puts Mexico and all of the Central American countries into North America. But people tend to blend the physical concept of “South America” with the cultural concept of “Latin America”. As a result, people will often want to put the North America / South America dividing line somewhere in the vicinity of Mexico. Of course, the Mexicans have no doubt that they live in North America! (Have you heard of NAFTA – the North American Free Trade Agreement?)

2) In the US, it is popular to designate ethnicity with a hyphenated term, where the second word in the term is “American”. Two of the most popular terms are “African-American” and “Asian-American” – both of which obviously refer to specific continents of origin. But you would never refer to someone of Algerian, Moroccan, or Egyptian heritage as an “African-American”. You would have to say “Arab-American” instead, which is clearly a cultural and regional term. On the other hand, it would be perfectly acceptable to refer to someone with Bahamian heritage as an “African American”. You would probably never use the cultural/regional term “Caribbean-American” for such a person. In other words, we associate certain physical characteristics with the term “African-American” – characteristics associated with people whose ancestors ultimately came from sub-Saharan Africa.

If I say “Asian-American”, most likely you would immediately think of people whose ancestors came from Eastern Asia – Chinese, Japanese, Korean, Vietnamese, etc. You might be somewhat surprised if you learn that I was referring to someone whose parents came from India. You would be even more surprised if you learn that I was referring to someone born in Israel. In fact, you might strenuously object, saying “That person is not an Asian-American!” Again, we associate certain physical characteristics with the term “Asian-American”, and if the person does not have those characteristics, then the term does not seem to fit. In short, our mental images for the terms “African-American” and “Asian-American” are both based in part on the old, discredited model of 3 human races – Caucasoid, Mongoloid, and Negroid – rather than the continent of origin.

But suppose we divided the world into “continents” – actually cultural regions – based entirely on ethnicity, culture, and language instead of physical geography. Further suppose that we are not allowed to divide the world into more than 9 major cultural regions. What would those regions be? Here is one possible list:

1) North America (US & Canada)
2) Latin America
3) Europe
4) Middle East (includes North Africa)
5) Sub-Saharan Africa
6) East Asia
7) South Asia
8) Pacific Islands
9) Anzac (Australia & New Zealand)

Although some of boundaries between these 9 cultural regions are a bit fuzzy, this list of world regions seems quite reasonable. Perhaps the most amazing thing about this list is that is correlates to a fairly high degree with our concepts of the physical continents – and yet it is not intended to reflect the physical continents at all. Each of the 7 standard continents (excluding Antarctica) matches up fairly closely to one of the 9 cultural regions – except for Asia, which is split into “East” and “South” cultural regions. (The two additional regions, not corresponding to standard continents, are the Middle East and the Pacific Islands.) This correlation is primarily due to the fact that the physical continents have always been a very important factor in shaping the boundaries of the various cultural regions of the world.

So back to the original question: Name all the continents in the world, and point out each one on a globe. Although the standard answer is that there are 7 continents – North America, South America, Europe, Asia, Africa, Australia, and Antarctica – this answer is not based on a clearly defined set of criteria. There is a competing model with only 6 continents – North America, South America, Eurasia, Africa, Australia, and Antarctica – that can be defined with a strict set of physical criteria. However, this model is not popular with the general public, because the popular concepts of “continent” blend human geography with physical geography. We can easily devise a model that divides the world into 9 (or fewer) major cultural regions – and this model has a lot in common with our popular concepts related to “continents” – but a model of cultural regions is unlikely to replace our model of continents. So for the foreseeable future, it appears that we will continue to muddle along with our muddled standard model of 7 continents.

That concludes our examination into the third class on our list – continents. We have now looked in detail at one specific type of mental model – a flat classification system containing only one class and no more than 9 items in the class. Our three examples were human senses, planets, and continents. We have seen that for each of these 3 examples, it is possible to construct an alternative model that logically is just as valid (if not more so) than the “standard” model. Yet in each case we teach our kids the standard model as if it were an enduring truth, rather than simply one possible model of many. In fact, I would say that it is beneficial to teach our kids that there is one standard model for each of these classification systems. These models, even if imperfect, are enormously helpful as tools that enable additional learning. But if we want our kid to be creative thinkers – if we want them to be able to “think outside the box” – then we should also teach them that alternative models exist, and that these alternative models, while non-standard, can provide some fascinating food for thought.

You may ask, “Are there any other classification systems of this same type – one class with no more than 9 items in the class – that play an important role in our culture and in our education system?” That’s a great question! In the future, each time that you or your child is asked to learn or make use of a simple classification system, you should ask yourself, “Is there only one class in this system, with no more than 9 items in the class?” If the answer is yes, then you have encountered the same type of classification model that we use for human senses, planets, and continents.

In the next chapter [a future essay], we’ll look at the next type of classification system – where a class is divided into a limited number of subclasses (no more than 9), but there may be many, many items in each class.

Copyright © 2010 by R. Philip Bouchard. All rights reserved.

Question: How many planets do we have in our solar system, and what are their names?

A strange thing happened in 2006. At the beginning of the year we had 9 planets in our solar system. But at the end of the year we had only 8 planets in our solar system. You might therefore ask, “What cataclysmic event could have caused us to lose a planet from our solar system?” The cataclysmic event was that we made a small adjustment to the definition of the term “planet”, and as a result, Pluto no longer qualified. The solar system did not change – it was only our model of the solar system that changed.

It has been known for centuries that our solar system contains more objects than are contained in our short list of planets. There’s the sun; there are moons; there are comets; there are asteroids. There are many other objects that don’t fit into any of these classes, for which we need additional classes. Furthermore, for some of these classes – such as comets – we know that we have not yet identified every object that falls into the class. In other words, we know that more comets will be discovered in the future. But in the case of planets, we have for thousands of years relied on a countable list of objects. On the other hand, the number of objects in the class has changed several times. Therefore the demotion of Pluto, and the reduction of the class from 9 objects to 8, was simply the most recent change to the class.

The original list of planets contained only 5 objects – Mercury, Venus, Mars, Jupiter, and Saturn. These are the 5 objects that appear in the night sky, which look a lot like stars to the naked eye, but which wander from one constellation to another instead of staying fixed in a particular constellation. So that was the original definition of a planet – a wandering star. As our model of the solar system improved, and we realized that the planets orbit around the sun instead of the earth, we came to realize that our own Earth was a planet too. So now the list had grown to 6 objects. As telescopes became stronger, and the mathematics of planetary motion became more refined, we came to realize that there are additional planets in our solar system, not visible in the night sky to the naked eye. So we eventually added Uranus to the list, then Neptune, and finally Pluto. But with each addition, we made the assumption that the newly discovered object can be reasonably categorized as a planet, rather than some other type of body.

However, Pluto was always something of an odd planet. First, it is smaller than any of the other planets. Second, it has an eccentric orbit that is less circular than the orbits of the other planets, so that sometimes Pluto is closer to the sun than Neptune. (When this happens we have to ask, is Neptune or Pluto the ninth planet?) Finally, the orbit of Pluto is tilted considerably compared to the orbits of the other planets.

None of these differences were very important when we thought that Pluto was unique. But in recent years we have come to realize that there are many Pluto-like objects out beyond Pluto. Most of these objects are smaller than Pluto, but at least one of these objects (named Eris) is bigger than Pluto. So this forced the question – should we consider some of these additional objects to be planets, and if so, then which ones?

Of course, this raises the question as to the precise definition of the word “planet”. From that definition, we need to derive a set of criteria – rules of thumb – that allow us to distinguish between planets and other objects in the solar system which aren’t planets. In our attempt to formulate such a definition, it may be helpful to ask ourselves questions such as these: Why aren’t moons considered to be planets? Why aren’t comets considered to be planets? Why aren’t asteroids considered to be planets? Are there any other objects in the solar system – besides moons, asteroids, and comets – which need to be distinguished from planets?

We exclude moons from the list of planets because moons do not revolve around the sun. Instead, moons orbit around planets. So our definition of a planet should mention that planets revolve around the sun.

Comets revolve around the sun, just as planets do. But their orbits are highly elliptical, rather than having the nearly circular orbits that planets have. Furthermore, the orbits often deviate significantly from the “ecliptic” – the plane that the planetary orbits occupy. In other words, the orbits of the planets constitute a set of concentric rings, all in the same plane (to within a few degrees). But the orbits of the comets are often not within that same plane. Therefore we might want our definition of “planet” to mention having a nearly circular orbit, and the definition should probably mention that the plane of the orbit is nearly the same as the plane of the earth’s orbit.

Asteroids revolve around the sun, just as planets do. Furthermore, most asteroids have nearly circular orbits, and the orbits are usually in the same plane as the earth (within a few degrees). Therefore it seems that asteroids would be good candidates to be classified as planets. However, we exclude asteroids from the list of planets primarily because they are too small to be considered planets. So our definition of a planet should mention a minimum size – although the precise minimum size is a judgment call, and therefore somewhat arbitrary.

If we consider only the inner parts of the solar system – let’s say everything inside the orbit of Neptune – then our four categories (planets, moons, comets, and asteroids) cover most (but not all) of the objects of interest, other than the sun itself. But if we define the solar system as including everything that orbits around the sun, along with anything that orbits around an object that orbits around the sun, then the solar system extends way, way beyond the orbit of Neptune. There are countless objects in the outer solar system, and the vast majority of these objects have never been catalogued. But what are these objects? Are they planets, moons, comets, asteroids, or something else altogether? As we gradually discover these objects, what criteria should we apply in order to assign them to the proper categories?

As we travel beyond the orbit of Neptune, the first region we pass through – still within our solar system – is called the Kuiper Belt. Astronomers have already discovered more than 1000 individual objects within the belt, but far more objects remain to be discovered. One estimate is that the region contains more than 70,000 objects with diameters greater than 100 km (60 miles). The belt occupies a flat ring of space that is more or less in the same plane as the planetary orbits.

Beyond the Kuiper Belt – but still within our solar system – lies the Oort Cloud. The Oort Cloud is thought to be the source of all the long-period comets that enter the inner solar system, such as Hale-Bopp. Unlike the Kuiper Belt, which lies in the same plane as earth’s orbit, the Oort Cloud is a vast sphere that lies in all directions from the sun, extending as far into space as the sun’s gravitation field can have an effect. It is believed that the cloud may contain trillions of objects greater than 1 km in diameter. However, because of the great distance from the earth, no object residing in the Oort Cloud has ever been directly observed. The main evidence for the Oort Cloud is that the orbital paths of the long-period comets indicate that they all originated in this region.

Between the Kuiper Belt and the Oort Cloud lies a region called the Scattered Disc, although some astronomers consider it to be part of the Kuiper Belt. The periodic comets, such as Halley’s, appear to have originated in this region.

As a general rule, the objects in the Kuiper Belt and the Oort Cloud are icy, not rocky or metallic like Earth and the other inner planets (Mercury, Venus, and Mars). Because of their volatile composition, objects from this part of the solar system become comets should they journey into the inner solar system. In other words, when such an object approaches the sun, it develops a visible tail as some of the volatiles vaporize and stream away.

Given the above, how should we classify the various trans-Neptunian objects (TNOs) as they are discovered? Can we use the familiar categories of planets, comets, and asteroids for some of these objects? Do we need additional categories to describe some of these objects?

First let’s consider the term “comet” – which we can define as a small icy body that develops a coma (tail) as it approaches the sun. Such an object cannot have spent much time close to the sun, or else the volatiles would all have evaporated. Therefore such an object must have an extremely elliptical orbit around the sun, so that most of the orbit lies in the very cold regions of the solar system – but part of the orbit takes the object closer to the sun – much closer to the sun than the orbit of Neptune. Given this definition and rationale, most of the TNOs cannot be classified as comets – their orbits never take them close enough to the sun. However, most of the TNOs are potential comets. If their orbits should ever be perturbed due to gravitational interactions with large objects (such as the gas giant planets), then they could become comets. But in the meanwhile they are not comets.

Next let’s consider the term “asteroid”. It used to be that any object orbiting the sun that is not a planet or a comet could be called an asteroid. But the definition of the term has narrowed over time, because such objects in the inner solar system are quite different from such objects in the outer solar system. The main difference is that the objects in the inner solar system are rocky or metallic, like Earth and the other inner planets. Objects in the outer solar system are icy, consisting primarily of materials that turn into liquids or gases when exposed to temperatures like those found on Earth. The orbit of Jupiter is the approximate boundary between the rocky/metallic bodies and the icy bodies. Therefore the term asteroid is now limited to those small objects whose orbits are no farther from the sun than Jupiter. As a result, the trans-Neptunian objects are not asteroids.

So that brings us back to the term “planet”. Can any of the objects beyond the orbit of Neptune (including objects not yet discovered) be classified as planets? Given the earlier discussion, we might define the term “planet” as any object that orbits the sun, provided that the orbit is nearly circular, that the plane of the orbit lies within a few degrees of the ecliptic, and that the diameter of the object is at least half as great as that of Mercury. Of course, to be precise we’ll need to specify just how close to circular the orbit must be. And we’ll have to specify how many degrees from the ecliptic that the orbital plane can deviate. Keep in mind that this is not the only possible definition for the term planet, and that we will consider another possible definition before this discussion is concluded.

So let’s consider the 8 bodies that are unequivocally considered to be planets. All 8 objects orbit the sun, so let’s see how they compare with regards to the other criteria.

As you can see from this table, Mercury is the smallest of the 8 principal planets. It also has the most eccentric (non-circular) orbit, and the plane of the orbit deviates the greatest from the plane of earth’s orbit. Now let’s add Pluto to the table:

As you can see from the second table, Pluto scores worse than Mercury on all 3 measures. It is less than half the diameter of tiny Mercury, its orbit is less circular than that of Mercury, and its orbit is far more tilted than that of Mercury. Therefore, depending upon what we choose as our thresholds, we might say that Pluto fails 3 of the 4 criteria we have set to classify an object as a planet. The only criterion that Pluto meets is that it orbits the sun.

If we consider Mercury as setting the minimum standards that all planets must meet, then do any of the objects in the Kuiper Belt (and beyond) meet these standards? In other words, can we consider any of the 1000+ Kuiper Belt objects discovered so far to be planets? By the Mercury standard, each object must be at least as big as Mercury, have an orbit at least as round as Mercury’s, and have an orbital plane that is no more tilted than that of Mercury. Do any of the thousand known trans-Neptunian objects qualify?

As it turns out, only one of the 1000+ objects (Eris) is known to be larger than Pluto, but even Eris is smaller than Mercury. Therefore every one of the objects fails the size test. We don’t even have to consider the other two criteria. However, it is likely that many of the TNOs would fail one or both of these additional criteria as well. The upshot is that our solar system contains only 8 known planets, and it does not seem highly likely that the Kuiper Belt holds any undiscovered objects large enough to be considered planets.

If we can reject all the known planetary candidates in the Kuiper Belt based on size alone, then do we really need to consider the two orbital characteristics – eccentricity and inclination? Can’t we just define a planet as any object that orbits the sun, provided that it meets a certain minimum size threshold? In fact, in 2006 the International Astronomical Union (IAU) did exactly that. In response to the 2005 discovery of Eris, an object that is larger than Pluto, the IAU revised the definition of the term “planet”. However, rather than choosing an arbitrary size threshold based on units of length (for example, a minimum diameter of 4000 km) to distinguish a planet from an object that is too small to be a planet, the IAU chose another route. They chose a size criterion that would have a distinct physical effect. Thus the IAU’s definition of a planet is the following:

Planet – a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.

Notice that this definition includes 3 criteria. The second criterion is clearly related to size – the object needs to be big enough that its own gravitational forces have shaped it into a sphere. (If the object is spinning quite rapidly, then the sphere may be slightly flattened.) The third criterion is also related to size. If the object is massive enough, then it will not share its orbit with other objects that are also orbiting the sun; it will have cleared its orbit of all other such objects.

By this definition, both Pluto and Eris were excluded from the list of planets. However, the IAU also created a new category, called a “dwarf planet”. A dwarf planet meets the first two criteria, but is not large enough to have cleared its orbit of other objects. Pluto and Eris therefore fall into the category of “dwarf planet”. Several other objects in the solar system also quality as dwarf planets, including Ceres, the largest object in the asteroid belt. Unlike most of the other objects in the asteroid belt, Ceres is large enough to have rounded into a sphere. Two additional trans-Neptunian objects have also been designated as dwarf planets – Makemake and Haumea. There may be hundreds of additional dwarf planets in the outer solar system – either undiscovered, or not yet studied enough to know that they meet the criteria for a dwarf planet.

The 2006 definition from the IAU included a third size category. If an object is too small to have become rounded into an oblate spheroid due to its own gravitational forces, then it is designated a “small solar system body”. This cumbersome term covers asteroids, comets, and all the other small bodies. In fact, a wide range of sometimes overlapping terms have been proposed or used to designate specific subsets of the small solar system bodies. Some of the more interesting terms include “centaur”, “trojan”, and “TNO” (trans-Neptunian object).

So back to the original question: How many planets do we have in our solar system, and what are their names? The standard answer (since August 2006), the one that we now want our kids to learn in school, is that there are 8 planets in the solar system – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. However, when these kids grow up and have kids of their own, will this still be the correct answer? It is possible that new discoveries will have changed the count by then. But equally likely is that the definition of the term “planet” will have been tweaked again, resulting in a larger (or smaller) set of qualifying objects. So once again, just as with the human senses, we should teach our kids the standard model of the day – but we should also make it clear that other models are possible!

So that concludes our examination into the second class on our list – planets. What about the next class on our list – continents?

[Part 3, discussing the concept of "continent", will appear in a few days.]

Copyright © 2010 by R. Philip Bouchard. All rights reserved.

Can you answer the following questions?

1) How many human senses are there? What are they?

2) How many planets do we have in our solar system, and what are their names?

3) Name all the continents in the world, and point out each one on a globe.

Before we discuss the answers to these questions, let’s first think about the questions themselves. What exactly are we doing when we ask questions such as these? Each of these questions is based on a classification system. So when we ask questions such as these, we are testing how well the responder has mastered the details of the classification system. With these 3 questions, we assume the existence of three distinct classes – senses, planets, and continents. We also assume that for any “thing” that we can name, we can categorize that thing as either being in the class or not in the class. For example, a turtle is not in any of these three classes – it is not a sense, a planet, or a continent. Jupiter fits into one of our three classes, because it is a planet – but it is not a sense or a continent. Africa is a member of another class, because it is continent – but it is not a sense or a planet. And taste is a sense – but it is not a planet or a continent.

As we will see in later essays, there is more than one way to structure a classification system. However, the three classification systems above – senses, planets, and continents – share a similar structure. In each case, the class contains fewer than 10 items, so we can easily memorize the entire list of “things” in the class. Furthermore, we can easily discuss the class in isolation from all other classes. For example, when we first teach children about planets, we don’t usually discuss asteroids and comets – that comes later in their education. When we first teach children about continents, we don’t expect them to simultaneously learn the locations of all the countries in the world. But later on, when the kids start to learn the locations of various countries, the most important location identifier is the continent in which the country is located.

Did you find that these three questions all look familiar? Basic classification models such as these are a fundamental part of what we teach our kids in school. Once our kids start kindergarten, classification models are a key component of the curriculum from that point on. Furthermore, for each of the above questions – and for other questions of the same type – we expect our students to provide the one acceptable “right” answer. And yet in each case, as we’ll see shortly, it is debatable as to whether the “right” answer is the only reasonable answer.

Human Senses

Question: How many human senses are there? What are they?

The standard answer, of course, is that there are 5 human senses – sight, hearing, taste, smell, and touch. This answer is so embedded in our culture that we have a common phrase – “sixth sense” – that refers to a person’s ability to perceive things that most other people cannot perceive. And yet the traditional answer of 5 human senses is not the only reasonable answer to the question. Imagine that there is someone — say, a visitor from another planet – who is unfamiliar with the usual answer to the question. Now imagine that this visitor is given the task of itemizing all of the human senses. How many senses would be included in the visitor’s list, and what would those senses be?

Because the visitor is unfamiliar with the traditional answer, he must use a set of criteria – rules of thumb – to sort through the possible answers. The criteria are derived from the definition of the class. So the first step is to define the word “sense”. What exactly is a “human sense”?

It turns out that the wording you use to define the phrase “human sense” can have a big impact on how many “things” can be included in the class. However, I would define “human sense” as “the ability of a human body to detect external matter, external forces, or external sources of energy”. This detection is enabled by “sense organs” within the body. Therefore a more complete definition would be “the ability of a human body to detect external matter, external forces, or external sources of energy, using sense organs within the body”.

Based on the above definition, anything that we would consider to be a human sense should meet the following criteria:

1) The sense enables us to detect external matter (that is, matter that is not part of our body) or an external force or source of energy.

2) It is possible to explain the nature of the matter, force, or energy that is detected by this specific sense.

3) It is possible to identify the specific part of the body that serves as the sense organ for this sense.

4) It is possible to explain how the sense organ detects the external matter, force, or energy.

The five traditional senses all meet the above criteria, as summarized below:

Sight – detects light. The sense organs are the eyes. Receptors in the retina of the eye respond to certain wavelengths of light. There are 4 types of receptors in the retina, each responding to a specific range of wavelengths. This allows us to distinguish among the wavelengths, and we perceive the various blends of wavelengths as different colors. The optic nerve conveys the data from the eyes to the brain. The brain processes the data to construct our sense of vision.

Hearing – detects sound waves in the air. The sense organs are the ears. Sound waves in the air trigger vibrations in the bones of the inner ear, which are detected by “hair cells” that send the data to the brain via the auditory nerve. The data includes information such as the mix of frequencies (pitches) in the sound and the loudness of the sound.

Taste – detects certain kinds of molecules that come in contact with the tongue and other tissues inside the mouth. The sense organ is therefore the mouth. The receptors are located in “taste buds” scattered along the surface of the tongue and on certain other tissues such as the soft palate. There are at least 5 kinds of taste buds, capable of detecting sweet, salty, sour, bitter, and savory molecular compounds. As with the other senses, the data is transmitted to the brain via the nervous system, and the brain processes the data to result in our perception of taste. (However, when we eat food, the brain blends taste data and smell data to create our perception of taste.)

Smell – detects certain kinds of airborne molecules that enter the nose. The sense organ is therefore the nose. The receptors are located in the olfactory bulb within the nasal cavity. There are apparently hundreds of different kinds of olfactory receptors, providing us with the ability to detect and distinguish a wide range of odors. The data is conveyed to the brain via the olfactory nerve, and the brain processes the data to create our perception of smell.

Touch – detects objects which come in contact with our skin. The sense organ is therefore the skin. The receptors are located beneath the skin, and detect pressure upon the skin. The wide distribution of the receptors allows us to deduce various properties of the object touching us, such as its texture and size. As with the other senses, the data is transmitted to the brain via the nervous system, and the brain processes the data to produce our sense of touch. In addition to the pressure receptors, there are several other kinds of receptors in the skin, including hot, cold, and pain. However, these various sensations are traditionally lumped into the sense of touch.

Okay, so we know that our visitor from another planet will include at least 5 human senses in his list. But will he find any other human senses to add to his list?

The visitor – let’s call him Marvin – does indeed catalog some additional senses. The next sense on his list is the sense of balance, and this is what Marvin has to say about it:

Balance – detects the direction of the force of gravity, allowing humans to determine whether their bodies are exactly vertical or slightly tilted. Human have long bodies, yet they walk on just two feet, balancing their long bodies perpendicular to the ground. Their sense of balance is extremely helpful when performing such activities as standing or walking, allowing them to maintain their balance and not fall over. The sense organ is the located in the inner ear (the semicircular canals), but is quite distinct from the sense of hearing. Fluid in the inner ear reacts to gravity, allowing the organ to detect the direction of the gravitation force. The fluid also reacts to acceleration forces, such as movements of the head. This information is conveyed to the brain via the vestibular nerve.

Marvin also draws a distinction between the sense of touch and the sense of hot and cold. Therefore, in Martin’s list we see the following seventh sense:

Hot and Cold – detects heat and coldness. The sense organ is the skin. Receptors located in the skin react to increased or decreased heat energy. However, these are not the same receptors responsible for the sense of touch. The change in heat energy may be due to conduction – either from a hot or cold object touching the skin, or from hot or cold air or water touching the skin – or the change in heat energy may be due to a net gain or loss by means of thermal radiation, such as feeling the warmth of sunlight or the heat from a fire. As with the other senses, the data is transmitted to the brain via the nervous system, and the brain processes the data to produce the sense of hot or cold.

The upshot is that Marvin’s list itemizes 7 human senses:

1) Sight (vision)
2) Hearing
3) Taste
4) Smell
5) Touch
6) Balance
7) Hot and cold

On the other hand, some people who study human senses say that there are 9 human senses. The other two senses, not on Marvin’s list, are the sense of pain, and the kinesthetic sense. (The kinesthetic sense, also called proprioception, is the ability to sense the position in space of various parts of the body.) However, Marvin did not include these latter two senses in his list, because in his opinion they do not involve the detection of external objects, forces, or sources of energy.

So now we have 3 different lists of human senses – one that lists 5 senses, one that lists 7 senses, and one that lists 9 senses. Can we really say that one of these models is “correct” and that the other two are “wrong”? In fact, each of these three models has a certain value. So what should we teach our kids? Should we teach them all 3 models?

Personally, if I could choose which model to use for instruction in schools, I would choose the model of 7 human senses. The 9-sense model would be my second choice. The 5-sense model is the weakest, because it limits our thinking too much. Any yet, teaching any of these models to our kids – even the 5-sense model – provides a lot of value. Any one of these models provides a framework upon which our kids can attach knowledge that they acquire. Therefore any of these models facilitates additional learning.

I would definitely not recommend that we present all 3 models on an equal footing to our kids. We should present one model as the standard, especially to younger children. However, we should not hide the fact that other models exist. As the kids get a little bit older, and have already become quite familiar with the standard model, it can be quite beneficial to point out that other non-standard models exist. Discussing these alternative models with our kids can significantly stretch their imaginations, helping them to see things in a different way. This is good training for being able to “think outside the box” as they grow older.

As a side note, we might ask the question, “If the 5-sense model of human senses is the weakest model, then how did the model originate, and how did we get so attached to it?” In my opinion, the 5-sense model is not really a model of the senses, but a model of the externally visible sense organs. There are 5 such organs – eyes, ears, mouth, nose, and skin. I believe that the focus on externally visible sense organs is the reason for including only 5 senses in the traditional model – in a one-to-one correspondence with the 5 organs. We remain attached to this model, despite its weaknesses, because it is so deeply rooted in our culture. If, on the other hand, a science educator were to be given the task of creating a better model for use in the primary school curriculum, the educator would probably choose a model that includes more than 5 senses – perhaps 7 or 9.

Now, suppose that we were to extend the model to include not just human senses, but the senses of all vertebrate animals. Would this add any more senses to our list, or would the list remain unchanged?

The one strong candidate to add to our list is a magnetic sense of direction. Some animals, such as certain birds, have the ability to detect magnetic fields – in particular, the magnetic field of the earth. There is actually an organ in the animal’s body that detects the orientation of the earth’s magnetic field relative to the animal’s body – something like a magnetic compass. Animals that possess this organ have a built-in sense of direction that is not dependent upon landmarks or the position of the sun in the sky. Such an organ is especially useful to birds who migrate long distances over the ocean. Therefore, if our model is expanded to cover all vertebrate animals, then the 7-sense model should be expanded to include at least 8 senses.

As we look through the world of animals – and now let’s include invertebrates as well as vertebrates – we can see examples of senses that appear to be different than human senses. We see snakes sensing the world by flicking out their forked tongues. We see bats navigating by means of echo location. And we see insects using their antennae to gather information about the world around them. But upon closer examination, we see that all of these senses share certain characteristics with human senses. If we define the sense of the smell as the ability to detect various kinds of molecules in the air, then it doesn’t matter whether the animal uses a nose or some other organ to do so. If we define the sense of taste as the ability to detect various kinds of non-airborne molecules that come in direct contact with the sense organ, then it doesn’t matter whether the animal uses its mouth or some other organ to do so. If we define the sense of hot and cold as the ability to detect heat gain or loss – either by means of conduction or thermal radiation – then it doesn’t matter whether the animal uses its skin or some other organ to do so. Even the bat’s ability to navigate by echo location can be described as an extension to the sense of hearing.

So that concludes our examination into the first class on our list – human senses. What about the next class on our list – planets?

[To be continued... Part 2 of the essay will appear in a few days.]

Copyright © 2010 by R. Philip Bouchard. All rights reserved.

Part 5 – The Vowel Sounds

In parts 1 through 4 of this essay, we have been considering how we might (theoretically) rethink the English alphabet to create a much stronger correspondence between the letters and the sounds that they represent. But up to now we have only considered the consonant sounds. There are several reasons that the vowel sounds present a much more difficult situation:

1) We have only 5 letters in the Latin alphabet for representing vowels (a, e, i, o, u) – but by anyone’s count there are more than 5 vowel sounds in English.

2) The vowel sounds in English are far more variable than the consonant sounds. Among all the various dialects of English spoken around the world, most of the consonant sounds are pronounced in a consistent fashion. But the pronunciation of the vowels can differ considerably from one dialect to another. Indeed, it is the pronunciation of the vowels, perhaps more than any other factor, which distinguishes one English speaker’s “accent” from another.

3) The vowel sounds in English not only vary from place to place, but also they have gone through historical changes. The most notable evolutionary change in the vowel sounds was the “Great Vowel Shift” from 1450 to 1750, during which most of the vowel sounds changed significantly. Prior to 1450, the sounds represented by the vowel letters were essentially the same as in Latin or Italian. After the vowel sounds all shifted, we continued to use the old spelling of the words. For example, we used to pronounce the word “feet” like we now pronounce “fate”, the word “wipe” like we now pronounce “weep”, the word “boot” like we now pronounce “boat”, and the word “date” like we now pronounce “dot”. But as we adopted new words from other languages, where the letters represented different sounds, we also preserved the spelling of these words, despite the inconsistency. For example, the spelling and pronunciation of the word “machine” is due to its French origin. We’ve kept the Italian spelling and pronunciation of “lasagna”. And we’ve kept the Portuguese spelling of “piranha”, although we’ve changed the pronunciation a bit.

4) In English, unlike many other languages, we don’t freeze the position of our mouths during the pronunciation of most vowels. Instead, we change the shape of our mouths while pronouncing the vowel, so that the sound at the end of the vowel is different than at the beginning. As a result, most of our vowel sounds are “glides” or “diphthongs” instead of pure sounds. Even linguists don’t always agree as to which vowel sounds should be considered as glides, and which should be considered as diphthongs. A diphthong consists of two vowel sounds in quick succession, where both sounds have a similar strength. A glide also involves two vowel sounds in quick succession, but the glided vowel is weaker than the main vowel. Therefore the combination is not really two complete vowels, but one vowel with an attached glide. The distinction is subtle!

5) In English, we often “reduce” the vowel sound in certain unaccented syllables. (However, we don’t do this in all unaccented syllables.) The reduced vowel sound is generally pronounced in one of two ways – similar to the vowel in “but” or to the vowel in “bit” – regardless of what letter is used to represent the vowel. Such a reduced vowel sound is sometimes called a “schwa” in the phonics world, represented by the symbol “ə”. (However, in IPA the “ə” symbol is more narrowly defined, applying only to the sound in “but” and not the sound in “bit”.)

Now back to the question – how many vowel sounds are there in English? The following 16 one-syllable words could all be considered as having different vowel sounds. However, some of the words contain diphthongs (two consecutive vowel sounds), and thus can be eliminated from our count – provided that we can agree as to which sounds are diphthongs and which are not:

bat
bait
bet
beet
bit
bite
pot
boat
boot
cute
book
but
pout
void
pert
caught

To make headway on this question, we should start by focusing on a single dialect of English, so let’s start with standard American English, also called broadcast American English. This is the version of American English that most television broadcasters use, which in turn is largely based on the English spoken in the American Midwest, minus any distinctive regional features.

I’ll start by presenting the model that I was taught in grades 1 to 3 during the “phonics instruction” of my early elementary school years. Although this model is far from perfect, it provides a very good starting point for discussion. According to the model I was taught, English contains 12 vowel sounds, along with two diphthongs. The 12 vowel sounds in this model, each of which has a unique “phonics” symbol, are:

ā (called “long A”) as in “bait”
ă (called “short A”) as in “bat”
ē (called “long E”) as in “beet”
ĕ (called “short E”) as in “bet”
ī (called “long I”) as in “bite”
ĭ (called “short I”) as in “bit”
ō (called “long O”) as in “boat”
ŏ (called “short O”) as in “pot”
ū (called “long U”) as in “cute”
ŭ (called “short U”) as in “but”
ōo (called “long OO”) as in “boot”
ŏo (called “short OO”) as in “book”

In addition to the twelve basic vowel sounds, this model includes two diphthongs – “oi”/”oy” and “ou”/”ow”. Each of these two diphthongs is considered to be a combination of two basic vowel sounds, spoken in quick succession.

oi/oy as in “toy” or “noise”
ou/ow as in “cow” or “house”

(My phonics instruction also included a sound called “au”/”aw” as in “dawn” or “caught”, but this sound is not a diphthong, just a digraph. In fact, to my ear this was not a distinct vowel sound at all, so I simply ignored it.)

As a kid, I loved this aspect of phonics instruction, because it provided me with a clear model and a clear set of terms for categorizing and discussing the vowel sounds. However, I was always annoyed by the “long U” concept, which to me was not a vowel, but a consonant-vowel combination. I strongly felt that “long U” should be discarded, because any sound represented by “ū” could be more properly represented by “yōo” – and I expressed this opinion to my third grade teacher, who was polite but noncommittal to my argument. (Many dictionaries use a pronunciation guide that is nearly identical to the phonics system I learned – and in these dictionaries the pronunciation of “cute” is typically listed as “kyoot” – so you could say that the dictionary supports my third-grade argument.)

As a kid I perceived a second problem in the phonics system I was taught – and that had to do with the “r-controlled vowel sounds”. We were taught that there are 3 such sounds – “er”, “ar”, and “or”. (The digraphs “ir” and “ur” don’t count, because they are pronounced the same as “er”.) However, to me the “er” sound seemed to be a single pure sound – not a vowel followed by a consonant. My mouth does not move at any point while making the “er” sound – so where does the vowel end and the consonant begin? My conclusion was that “er” ought to elevated to the status of a distinct vowel sound – and that “ar” and “or” were therefore diphthongs – each involving another basic vowel sound following by the “er” sound. Needless to say, my third grade teacher was not interested in changing the phonics curriculum to align with my suggestions, although she was polite about it. Anyway, I learned as an adult that the r-controlled vowels pose a special problem for phonemic categorization, because in many English dialects, including most of those spoken outside the US, all trace of the “r” sound is eliminated. However, some linguists agree that “er”, when pronounced as in standard American English, can indeed be considered a pure vowel sound, and one of the IPA symbols used to represent this sound is “ɚ”.

By the way, the use of the terms “long” and “short” to categorize the English vowel sounds is somewhat misleading. In some languages, including German and Japanese, there is a genuine distinction between long vowels and short vowels. In these languages you can have two distinct vowels that are pronounced in exactly the same way, the only distinction being that the long vowel is pronounced for a longer period of time than the short vowel. This concept does not exist in English, where each of the “long” vowels has a distinctly different sound than the corresponding “short” vowel. However, in standard American English, the long vowels tend to be complex, involving glides or diphthongs, while the short vowels tend to be more pure, with no glide or only a small glide. This rule of thumb breaks down when you consider other dialects of English. In the southeastern US, where I grew up, some people speak dialects of English where many of the “short” vowels are pronounced with a complex sequence of sounds.

(Side note: When I was a young adult teaching English as foreign language in South America, the head of instruction at the institute where I taught was a native of Germany. Her biggest pet peeve regarding the American instructors was the tendency to refer to the English vowel sounds as “long” or “short”. She absolutely could not tolerate this, and would launch into a furious rant if she heard any of us using these terms.)

My childhood mental model of 11 distinct vowel sounds (having eliminated “long U”) was challenged when, as an adult, I began work on a computer-based project for phonics instruction in elementary schools. At this time I realized that about half of my colleagues made a phonemic distinction between pairs such as “cot” and “caught”, which sounded identical to me. At last I understood why most dictionaries also made such a distinction in their pronunciation guides. (For example, the American Heritage dictionary uses “ŏ” for one of these sounds and “ô” for the other.) I also came to realize that there were certain words that were not members of such minimal pairs, and yet which could be categorized as having either the same vowel sound as “cot” or the same vowel sound as “caught” – and I was amazed to learn that these colleagues of mine could accurately predict which symbol (“ŏ” or “ô”) the dictionary would assign the vowel in each word. So for these people, there were 12 distinct vowel sounds in English, compared to my 11.

ô as in “caught”

However, we can reduce the count of vowels, and thus the number of distinct symbols needed, if we consider some of these 12 vowel sounds to be diphthongs – that is, a combination of two simpler vowels. Linguists appear to be in universal agreement that the “ī” sound is actually a diphthong – two consecutive vowel sounds – which in the phonics notation would be equivalent to ŏ+ē or ŏ+ĭ. Linguists are divided as to whether “ā” is a glide or a diphthong, but the mouth dramatically changes shape during the pronunciation of the vowel – so to my ears it is clearly a diphthong, equivalent to ĕ+ē or ĕ+ĭ. Likewise, the mouth dramatically changes shape during the pronunciation of “ō”, but if this is a diphthong, then what simpler vowel constitutes the first part? The best candidate in American English is probably “ô”, the sound that some people use for pronouncing “caught”. So “ō” can be considered as equivalent to ô+ ōo or ô+ŏo. (In the UK, “ŭ” may be a better candidate for the first vowel in this diphthong.)

This brings us down to 9 distinct vowel sounds, with the resulting need for 9 distinct vowel symbols. However, both ē and ōo are somewhat glided – the mouth closes a bit during the pronunciation of the vowel. We could use this fact as an argument for also treating these two vowel sounds as diphthongs, thereby bringing the number of distinct vowel sounds down to 7 – if we can figure out an appropriate set of symbols for the two parts of the vowel sound. (We’ll return to this question in a moment.)

As we did with the consonants, we will create 3 versions of PEA (Phonemic English Alphabet) for the vowels. In PEA-1 we will minimize the number of additional letters by assuming that there are only 7 basic vowel sounds in English, and that the remaining vowel sounds can be treated as diphthongs. In PEA-2 we will assume that there are 9 basic vowel sounds in English, and that the rest can be treated as diphthongs. Thus the alphabet for PEA-2 will have more vowel letters than PEA-1 does. In PEA-3 we will limit ourselves to the 26 traditional English letters, which means that we have to assign digraphs to some of the basic vowel sounds, just as we did with certain consonants in PEA-3.

This leaves us with several issues to work out for PEA-1 and PEA-2:

1) Assuming that we want each letter in the alphabet to consistently represent a specific sound, then which five sounds should we assign the 5 traditional vowel symbols – a, e, i, o, and u?

2) Assuming that we treat all but 7 or 9 of the vowel sounds as diphthongs, then which of the basic vowel sounds will get assigned new symbols other than a,e,i,o,u – and what should these additional symbols be?

3) Assuming that all of the remaining vowel sounds can be treated as diphthongs, then what two component sounds constitute each diphthong? In other words, what pair of letters should we use for the diphthong?

The first question may be the easiest. For PEA-1 and PEA-2, I recommend that the five traditional vowel symbols – a,e,i,o,u – should represent nearly the same sounds that they represent in Latin or Spanish (just as they did in English prior to 1450). Furthermore, the symbols should represent vowels that are essentially “pure”, with little or no glide in the vowel. Using this standard, the pronunciation rules for written English will be much more consistent with other languages that use the Roman alphabet – which in turn will make it easier for non-English speakers to learn English, and for English speakers to learn other languages. Therefore the five traditional vowel symbols can represent the following phonemes:

“a” = “ŏ” or “ä” (IPA /ɑ/ or /ɒ/) as in bark, dart, or yard, or as represented by the “o” in hot or rod (see Note 1)
“e” = “ĕ” (IPA /ɛ/) as in bed, desk, or help
“i” = “ĭ” (IPA /ɪ/) as in bid, grit, or hilt
“o” = “ô” (IPA /ɔ/) as in born, lord, or tort (see Note 2)
“u” = “ŏo” (IPA /ʊ/) as in put, or as represented by the “oo” in book

Note 1: Some people may consider this to be two distinct vowel phonemes, but in standard American English this is generally a single phoneme.

Note 2: For people who distinguish between the vowels in “cot” and “caught”, this is also the vowel sound in “caught”.

The two remaining “pure” vowels are those corresponding to the phonics symbols “ă” (as in “cat”) and “ŭ” (as in “bug”). In IPA these sounds can be represented as /æ/ and /ə/, respectively. We could use either the phonics symbols or the IPA symbols – but I recommend using the two phonics symbols, because I think that they will be less confusing to people.

Now let’s look at the vowel sounds that we will consider to be diphthongs or glides, and therefore will represent using digraphs:

ā as in “bait” (diphthong)
ē as in “beet” (glide)
ī as in “bite” (diphthong)
ō as in “boat” (diphthong)
ōo as in “boot” (glide)
ou/ow as in “house” or “howl” (diphthong)
oi/oy as in “boy” or “void” (diphthong)

There are several ways we could approach this – but here is one simplifying assumption. In every glide or diphthong in standard American English, the mouth moves from a more open position to a more closed position. In fact, there are only two possible ending positions, roughly corresponding to the vowel sounds that we have assigned to the letters “i” and “u”. However, these ending positions also correspond to the semi-vowels “y” and “w” – and this correspondence feels more accurate. Therefore we can write all seven of the above sounds as a digraph in which the first letter is one of our 7 basic vowels, and the second letter is either “y” or “w”. As a result, the above seven sounds will be written in PEA as follows:

ā as in “bait” is the diphthong e+y, and therefore will be written as “ey”, as in “grey”
ē as in “beet” is the glide i+y, and therefore will be written as “iy” (PEA-1 only)
ī as in “bite” is the diphthong a+y, and therefore will be written as “ay”
ō as in “boat” is the diphthong o+w, and therefore will be written as “ow”, as in “blow”
ōo as in “boot” is the glide u+w, and therefore will be written as “uw” (PEA-1 only)
ou/ow as in “house” is the diphthong a+w, and therefore will be written as “aw”
oi/oy as in “boy” is the diphthong o+y, and therefore will be written as “oy”

Note that these are not arbitrary assignments. In each case, the first letter of the digraph corresponds to the “simple vowel” that is most similar to the beginning sound of the diphthong or glide. The second letter indicates which of the two semi-closed positions terminates the diphthong or glide.

Now let’s look at the three “r-controlled” vowel sounds – “er”, “ar”, and “or”. These pose a special challenge. In standard American English, the “r” in these combinations is clearly pronounced. But in some dialects of American English (such as Boston, and the coastal plain of the Deep South), the “r” is not pronounced. (Linguists use the terms “rhotic” and “non-rhotic” to make this distinction. Most dialects of English spoken outside of North America are non-rhotic.) To my ear, in standard American English “er” sounds like a unique, pure vowel, while “ar” and “or” sound like diphthongs in which the second vowel sound is “er”. However, one of our rules for PEA-1 is to minimize the number of symbols in the alphabet, while still maintaining a 1-to-1 correspondence between sounds and symbols. Therefore, for PEA-1 we will follow convention and consider the “r” in these r-controlled vowel sounds to be a normal consonant. The sounds “ar” and “or” will continue to be written as “ar” and “or”. In rhotic dialects such as standard American English, I find it hard to match the vowel sound in “er” to any of the other vowels already in the list – the “er” vowel sound appears unique to me. But in non-rhotic dialects, the sound I hear people speak sounds to me like the “u” in “but”, to which we have assigned the symbol “ŭ”. When people speaking such dialects say the word “butter”, it sounds to me like “bŭtŭ”. Therefore in PEA-1 we will assume that the vowel sound in “er” can be represented as “ŭ”, and we will use “ŭr” as the spelling for the “er” sound.

For PEA-2, when we discussed the consonants, we relaxed the rule to minimize the number of new symbols. The same concept will apply to the vowels. In PEA-1 we treated two vowels with minor glides as diphthongs:

ē as in “beet” will be written as “iy” (PEA-1 only)
ōo as in “boot” will be written as “uw” (PEA-1 only)

But for PEA-2 we’ll elevate these two sounds to the status of distinct vowels, each with its own unique symbol:

ē as in “beet” will be written as ï (PEA-2 only)
ōo as in “boot” will be written as ü (PEA-2 only)

The concept here is that the two dots indicate a glide at the end of vowel sound, which distinguishes the vowel from the similar vowel written without the two dots. So “ï” sounds a lot like “i”, except for the glide, and “ü” sounds a lot like “u”, except for the glide.

In PEA-2 we’ll also introduce a special variation of the “r” symbol – ř – to use with r-controlled vowels. This will allow us to treat the “er” sound as a unique, pure vowel sound, written as “ř”. In contrast, the “ar” and “or” sounds are considered to be diphthongs in PEA-2, and are written as “ař” and “oř”. This notation also works reasonably well for the non-rhotic dialects, because it clearly distinguishes between the consonant “r” (which is always pronounced) and the vowel “ř” which is either not pronounced or is reduced to something like “ŭ”.

So now let’s compare the spelling of several words in traditional English spelling, PEA-1, PEA-2, and two distinct interpretations of IPA:

Now, using either PEA-1 or PEA-2, we have a system for spelling English words that can provide a 1-to-1 correspondence between the sounds of the language and the symbols used to represent those sounds – in other words, a truly phonemic spelling system. However, because English has more than 26 consonant and vowel sounds, both PEA-1 and PEA-2 contain more than 26 letters. In PEA-1 we used a very conservative count of the unique sounds (phonemes), and we ended up with the following 29 letters in the alphabet:

a ă b c d e f g h i j k l m n o p q r s t ð u ŭ v w x y z

In PEA-2 we used a slightly more liberal approach for counting the number of unique sounds in the English language, and we ended up with the following 32 letters in the alphabet:

a ă b c č d e f g h i ï j k l m n o p r ř s š t u ŭ v w x y z ž

That leaves us with the final challenge. In PEA-3 we must restrict ourselves to the 26 traditional letters. Therefore we must use digraphs for some of the phonemes – where two letters written in sequence represent a single unique sound. (An example from the consonant phonemes is “sh”.) In PEA-1 we minimized the number of new symbols by adopting the convention that English has only 7 unique vowel sounds, and that all of the other vowel sounds are actually diphthongs. As a result we only had to introduce two new symbols for the vowels. If we adopt the same approach for PEA-3, where we use digraphs instead of new symbols, then we will have to employ at least two vowel digraphs.

A key rule of thumb for PEA-3, as we saw with the consonants, is to choose traditional digraphs that are readily recognized by current English speakers – especially if the digraphs help to make PEA-3 more consistent with the traditional spellings of words. The most obvious example is to use “oo” to represent the vowel sound in such words as “boot” and “noon”. (Note, however, that “book” has a different vowel sound, even though it too is traditionally spelled with “oo”.) So it might make sense to replace the “uw” diphthong in PEA-1 with the digraph “oo” in PEA-3. However, this does not actually eliminate either of the two new vowel symbols that we introduced in PEA-1, which are ă and ŭ.

The digraph “ah” is readily recognized and understood by English speakers, even though it is seldom used in the traditional spelling of words. This digraph corresponds to the symbol “a” in PEA-1. If we employ this digraph in PEA-3, then this frees up the symbol “a”, which we can then use to represent the vowel sound in the word “bat”, thereby eliminating the symbol “ă”. However, in this approach, the diphthong “ay” now has to be spelled “ahy”, and the r-controlled vowel “ar” now has to be spelled “ahr”. (On the other hand, the diphthong “aw” can be left alone, because it still makes sense even with the new vowel sound assigned to the symbol “a”.)

The digraph “uh” is also fairly well recognized by English speakers – although it is almost never used in the traditional spelling of words. If we replace the “ŭ” symbol in PEA-1 with the digraph “uh”, then the pronunciation of the digraph should be fairly clear. However, this is an extremely common vowel sound in English. In contrast, the vowel sound in “book”, represented by “u” in PEA-1, is relatively rare. So I suggest swapping the spelling convention for these two sounds. In PEA-3, the vowel sound in the word “but” will be represented by “u”, while the vowel sound in the word “book” will be represented by the digraph “uh”. This change will help to make the spelling under PEA-3 a bit more similar to traditional spelling. It also allows us to use “ur” instead of “uhr” for the r-controlled vowel. However, under this approach, it no longer makes sense to use “uw” to represent the vowel sound in “boot”, so we’ll use the traditional “oo” digraph instead.

In each of the three versions of PEA, any given phoneme is always written in a consistent fashion, using a unique letter symbol, or a unique pair of letter symbols. The table below lists all of the consonant phonemes of English, along with the corresponding spelling for the phoneme:

The following table lists all of the vowel phonemes for standard American English, along with the corresponding spelling in each of the three versions of PEA.

We are nearly finished now – our definition of the Phonemic English Alphabet is essentially complete. In the final installment of this essay, coming in a few days, we will transcribe a few sample texts from the traditional English spelling into PEA-1, PEA-2, and PEA-3. At the same time, we will address the final few questions, such as what punctuation conventions to use.

Copyright © 2010 by R. Philip Bouchard. All rights reserved.