Binary categorisation: The raw, the cooked, the rare and the chocolate

By Gordon Rugg & Jo Hyde

Human societies like dividing things into two categories. They’ve been doing it for a long time. For instance, a large chunk of Leviticus in the Old Testament is about dividing things into the categories of clean and unclean. The Codes of Hammurabi involve dividing things into the legal and the illegal. There are plenty more examples where those came from. This article is about ways of visualising how people divide up their world when they go beyond the simple two-category approach.

The image below shows occurrences of “unclean” (red squares) and “clean” (green squares) in Leviticus, using Search Visualizer: www.searchvisualizer.com

Both terms occur repeatedly throughout the text, but “unclean” is significantly more common. This emphasis on prohibition rather than on permission is a theme that occurs repeatedly in other applications of this way of thinking, as we discuss below.

The two-category approach is still very much alive today, with divisions such as male/female, adult/child, human/non-human, legal/illegal and many others widespread across present-day societies.

The fact that a concept has been widespread for a long time doesn’t mean that it’s the best idea, though. Humans have their opinions about the world, but reality has a habit of exerting its right to differ.

This can lead to some serious complications in society, when people grapple with concepts that don’t fit neatly into a two-category worldview. It often also leads to misunderstandings about what people are actually trying to say with their proposed solutions.

One way of reducing these complications and misunderstandings is to use visualisations systematically. That’s a very different proposition from using visualisations unsystematically, or waving around nice-sounding truisms like “A picture is worth a thousand words” which don’t actually give you any guidance on what to do.

We’ve been looking at ways of providing systematic guidance, by bringing in concepts from measurement theory and set theory, among other places. This article is about some of the resulting ideas, which can be used without needing to get into the mathematical underpinnings.

A lot of binary categorisations bring heavy baggage with them, from religion and ethics and politics, so we’ll use a worked example which is less emotive. However, the underlying principles from this example can be directly applied to areas such as gender theory and politics, with questions like whether gender can be categorised in better ways than just “male” versus “female”.

In this article, we’ll examine at a distinction from social anthropology, between the raw and the cooked. This one is widespread across societies. Among other things, many societies find it a handy way of differentiating humans, who cook their food, from animals, which don’t. It’s the title of a classic 1964 book by the French anthropologist Claude Lévi-Strauss (Le cru et le cuit, in the original).

You can represent this as an either-or choice; something is either raw, or cooked, with no other options. Readers who speak French will have already spotted that the original French “cuit” doesn’t exactly correspond to English “cooked” – we’ll return to this point later.

Visually, the distinction between cooked and raw can be represented by boxes with crisp, distinct edges, like this.

However, reality is more complicated. Where would a very rare steak fit into this view? The steak may be cooked on the outside, but it’s still raw on the inside.

This is the point where, in cases involving religion and politics, a lot of people pull out the “slippery slope” argument, and claim that if you don’t have clearly distinct boxes, then there’s a slippery slope from the apparently minor first examples down to Very Bad Things, such as the breakdown of society, the end of the world, and dogs living with cats.

That view can be represented like this, with a fuzzy greyscale.

However, other options are possible. Here’s one as a start.

In this representation, some foods are definitely cooked, and others are definitely raw, while there’s an intermediate greyscale category between them. This lets us fit in not only rare steak, but also food which has been prepared without being actually cooked, such as sushi (bringing us back to the French term cuit used by Lévi-Strauss, which includes the meaning of prepared as well as of cooked).

The story doesn’t end there, though. There’s another category which is neither raw nor cooked, but that isn’t on a greyscale, namely processed foods such as chocolate.

One way to represent that is with another intermediate box, this time with a homogeneous fill to indicate that the box doesn’t contain a greyscale.

That’s not the whole story, but it’s a start.

So, in summary, people use binary distinctions a lot, and binary distinctions can be useful as a quick and dirty first pass for dividing the world into categories that look easy to handle mentally. Structural anthropologists such as Lévi-Strauss spent a lot of time looking at this type of binary categorisation across societies.

However, when you move beyond “quick and dirty” into “thorough” then binary distinctions often start to hit problems. Fields such as law and medicine and public policy need to handle all cases, not just most cases. Legal test cases are usually about just this type of uncertainty regarding categorisation. The ripple effects from a single legal test case can change society dramatically, for better or for worse. It’s a similar story with political debate, which often ends up being framed as binary either-or choices, when reality is more complex.

Using the right visualisations can help clarify what is actually going on, as opposed to an oversimplified version of events. This article described some types of visualisation. We’ll be looking at other types of visualisation in future articles, and we’ll also be looking at ways of selecting the most appropriate visualisation for a given situation.

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