Sirius Geography

What are Continents?

The Cambridge English dictionary definition of a continent is one of the seven large land masses that are mostly surrounded by sea[i]. That seems to make sense but is also quite vague and raises a lot of questions when digging deeper: Why are Europe and Asia two continents, when they form a continuous landmass with no sea barrier between them? Why is Greenland not a continent when it is a very large landmass surrounded by water? Why are there seven continents and why is that part of the definition? Japan is a group of islands that are not connected to the main Asian landmass. Is Japan still part of Asia? These are just a few of the many issues raised by this definition. This article examines what exactly continents are and how to define them.

Dividing the Land

Our brains are hardwired to categorise and group things together to make sense of the complex world around us[ii]. Not surprisingly then, we have divided the world into different parts and groups to make sense of it. One example of a division is a country, which is an area of land that has its own government[iii]. Because most countries are quite large, it makes sense to further divide countries into smaller units like states or provinces. Such divisions are useful to describe where something is located or to analyse, compare, or contrast things like wealth, safety, or weather patterns. Depending on the purpose of a grouping, we need either large or small-scale groups. Postal codes, for example, help us locate a specific location while geopolitical regions help us understand global issues better. Continents are the largest category we use to group the land on our planet. (Hemispheres are larger categories but include the oceans; continents are the largest categories for land). In other words, they are the last stop before we describe a place on land as being part of planet earth. Stanford professors Martin Lewis and Karen Wigen describe continents as “the most basic information—the highest level of our geographic taxonomy[iv].”

Tricky Division

Dividing land into continents is tricky because there is no universally agreed definition of what is required for a land mass to be considered a continent. The purpose is to create a useful category, which means that having a system that either creates too many or too few items in the category, or one where too different to be comparable (e.g. in size or population) misses this purpose. Based on this premise it is obvious that not every island should be considered a continent but it is not as obvious where to draw the line. There are no clear natural boundaries that would create a useful definition. With sea boundaries it would be unclear when an island would turn into a continent. Proper sea boundaries would also create a single massive continent comprising Africa, Asia, and Europe (“Afroeurasia”) that would comprise over 86% of the world’s population and close to 60% of the earth’s land, and include so many cultures, economies, and diverse histories that it would not make it a very useful category. Using the underlying geology in the form of tectonic plates as a measure is also not satisfactory as it would cut through well-connected areas (e.g. cutting away south-east China from the rest of Eurasia and east Africa from the rest of the continent). Using tectonic plates would also create far too many continents to be useful: Some researchers suggest that there are as many as 159 tectonic plates[v]. Another issue is that many plates are mostly covered by ocean with barely any land.

Unfortunately, there does not seem to be a single physical criteria that would offer a clear and useful delineation of continents. Historic definitions are no help either as they no longer work with our current understanding of the world (the ancient Greeks neatly divided the earth into three spheres of Europe, Asia, and Libya—now Africa—based on the sea boundaries of the Aegean Sea and the Mediterranean). Cultural, political, or biogeography also do not offer clear boundaries. Western Europe and East Asia are very different on all of these markers but there is no clear line where a drastic change occurs. Rather, there are gradual shifts across the east-west axis. Apart from having to decide the boundaries between continents, it is also not clear what a continent should encompass. Historically, continents have been seen as continuous landmasses (the name itself comes from the Latin term terra continens, meaning “continuous land”). We still use this term to distinguish, for example, continental Europe from Britain. But does that mean that it is not part of Europe? The UK may have left the European union but is it still part of Europe as a continent? Most geographers would say it is[vi].

Problems Everywhere

Finding a clear dividing line for categories is not unique to continents or geography. A famous example is the sorites paradox that has been attributed to the ancient Greek philosopher Eubulides of Miletus (4^th century BC)[vii]^,[viii] that describes how adding a single grain of wheat to another does not turn it into a heap—inversely taking away a single grain from a heap will not result in it no longer being a heap. By this logic, even adding a single grain a million times should not result in there being a heap or taking away a single grain as many times should not remove the heap, which is obviously not the case. The issue with this seeming paradox is that “heap” is a vague term with blurred boundaries[ix]. Other vague terms create similar problems with delineating categories, such as middle-aged versus old, tall versus normal height, or blue versus green[x].

A Solution

As these examples show, there are many categories that are hard to define precisely. Unlike grain heaps, continents are one of the most basic geographic groups, which makes an unclear definition extremely difficult and unsatisfying. How we define continents is not just an issue for how to draw maps but guides our basic conceptions of our world. Lewis and Wigen give the example that when we talk of African wildlife, we think of it as a distinct assemblage of animals and commonly compare it to the fauna of Asia or South America[xi]. Similarly, Asian culture or the European economy bring to mind a clear grouping that is different from African culture or economy. Because of the need for a clear continents have been defined by convention rather than based on a single, specific rule. While a lot of thought has gone into these definitions, they ultimately represent specific choices rather than naturally occurring or obvious boundaries. The result of this process is that there are several different models with different continents. These models firstly need to decide on boundaries between continents and secondly decide whether offshore islands are part of continents or not. Geologist consider the submerged continental shelf as part of continents, including all the islands on it[xii]. As such, Britain is part of Europe and Japan part of Asia. However, by this definition Hawaii and other island groups would either be stand-alone continents or not part of any continent. Since we think of continents as a grouping of areas, most models assign islands (like Hawaii) to a continent even if they are not connected to the main continental landmass or sit on a continental shelf. Again, what is included is defined by convention and individual models use different approaches.

The 7-Continents

By far the most widely used one is the 7-continent model[xiii]^,[xiv] that uses the following continents from largest to smallest:

• Asia
• Africa
• North America
• South America
• Antarctica
• Europe
• Australia/Oceania

Other Options

There are several other models and good arguments can be made for many of them, especially for combining Europe and Asia as well as North and South America. This is especially true from the point of view of countries that span across continent boundaries, like the former Soviet Union. Some models exclude Antarctica since it mostly uninhabited. At the same time, there are strong arguments for the 7-continent model. (For more information, see our article on continent models). Using convention to define continents means that models are up for debatable and schools in former Soviet countries as well as Japan still widely teach a 6-continent model, while most other countries use the 7-continent model in their school curricula.

Summary

Continents are the largest category we use to divide the landmass of the earth. There are no satisfying natural, biogeographical, cultural, or political criteria to define continents, which is why they are defined by convention rather than by clear standards. Because of this approach, there are multiple continent models. The most widely used model divides the world into seven continents: Asia, Africa, North America, South America, Antarctica, Europe, and Australia.

[i] Cambridge Dictionary. (2021). Continent. URL: https://dictionary.cambridge.org/dictionary/english/continent

[ii] Kelly, M. (2013). Subconscious mental categories help brain sort through everyday experiences. Princeton Unviersity News. URL: https://www.princeton.edu/news/2013/04/10/subconscious-mental-categories-help-brain-sort-through-everyday-experiences

[iii] Cambridge Dictionary. (2021). Country. URL: https://dictionary.cambridge.org/dictionary/english/country

[iv] Lewis, M. W., & Wigen, K. E. (1997). The myth of continents: A critique of metageography. Berkeley, CA: University of California Press. P. 1

[v] Harrison, C. G. A. (2016). The present-day number of tectonic plates. Earth, Planets and Space 68, 37. https://doi.org/10.1186/s40623-016-0400-x

[vi] Garton-Ash, T. (2001). Is Britain European? Guardian. URL: https://www.theguardian.com/weblogarticle/0,,194421,00.html

[vii] Hyde, D., & Raffman, D. (2018). Sorites paradox. In E. N. Zalta et al. (Eds.) Stanford Encyclopedia of Philosophy. URL: https://plato.stanford.edu/entries/sorites-paradox/

[viii] Encyclopaedia Britannica (1998). Eubulides of Miletus. Encyclopedia Britannica. URL: https://www.britannica.com/biography/Eubulides-of-Miletus

[ix] Hyde, D., & Raffman, D. (2018). Sorites paradox. In E. N. Zalta et al. (Eds.) Stanford Encyclopedia of Philosophy. URL: https://plato.stanford.edu/entries/sorites-paradox/

[x] Hyde, D., & Raffman, D. (2018). Sorites paradox. In E. N. Zalta et al. (Eds.) Stanford Encyclopedia of Philosophy. URL: https://plato.stanford.edu/entries/sorites-paradox/

[xi] Lewis, M. W., & Wigen, K. E. (1997). The myth of continents: A critique of metageography. Berkeley, CA: University of California Press. P. 1

[xii] National Geographic. (2011). Continental shelf. National Geographic. URL: https://www.nationalgeographic.org/encyclopedia/continental-shelf/

[xiii] Central Intelligence Agency. (2015). The World Facebook 2016-2017. Washington, DC: U.S. Government Printing Office.

[xiv] World Atlas. (n.d.) Continents of the world. World Atlas. URL: https://www.worldatlas.com/continents