The Wax Example

Descartes argues that he is a res cogitans, a thinking thing. He is a thing that "doubts, perceives, affirms, denies, wills, does not will, that imagines also, and which feels". Some of these attributes seem to link mental states to physical states, for example to our sense organs. Surely, to perceive something is to experience it through our senses? But Descartes insists that the essential features of perception are intellectual rather than sensual.

One purpose of the wax example is to demonstrate this point. Wax makes an excellent example because it connects with all the senses.

The wax has a certain colour, smell, taste. It is hard to the touch and makes a sound when tapped. But when it melts all these sensory properties change. The appearance, smell, taste, sound, and texture all change - and yet, Descartes says, he perceives it to be the same wax. This shows that the wax is not its sensory properties, for if it were its colour, taste, smell, etc. could not change without it being different wax. So when he thinks of the wax he is thinking of something that is extended (takes up space) and changeable.

It is not through imagination that he knows what it is, for he knows that it can go through more changes than he can imagine. If it's not through the senses, nor through imagination, that he perceives the wax, how does he do it? The answer is: through his understanding - ie intellectually. When he says he "sees" the wax (visually), what he is really doing is making an intellectual judgement.

He backs this up with the example of looking out of his window and seeing a man in the street below. What he actually sees from above is a hat and cloak moving along. But he makes a judgement that there is a man underneath (rather than a machine). He does not see the man visually; he makes an intellectual judgement that it is a man.

Notice that these examples are about how we know things. Although the wax example is sometimes seen as reinforcing the cogito argument, and the distinction between mind and matter, it is mainly about how we know things about the physical world. It makes a point about the nature of matter too, of course. The wax is not essentially its sensory properties; it is essentially those properties that are perceived intellectually.

This is not such an extraordinary idea - after all, nowadays we don't think that physical objects are really as we perceive then with our senses; we don't see protons and electrons, do we? But, on the other hand, we don't generally think of our recognition of objects as being an intellectual activity: we tend to think that we just see things, hear things, touch things, etc - in other words, that we know things through our senses. But surely Descartes is right. When we see things as something - eg a black shape as a cat - that is surely at least partly an intellectual judgement. Cats, of course, don't normally change all their sensory properties as we look at them, as the wax does. That's why the wax example is so well chosen, and why we wouldn't normally accept what Descartes says about true perception" (by which he means something close to recognition or identification) is an intellectual judgement. But if it true in the case of wax, it is perhaps true in the case of all perception. We intellectually judge or infer the presence of physical objects from their sensory properties, but the only physical properties we can judge objects really to have are extension and changeability.

So the first purpose of the wax example is to make a point about how we have knowledge of physical objects. The second purpose is to say something about what the essential properties of physical objects are.