Ontic Structural Realism, forms, and Aquinas’s philosophy of mind

In my last couple posts (first here and second here) I have been looking at what I now know is called ‘Ontic Structural Realism’ — the idea that all that exists are the structures of relationships between things, and that things have no meaningful existence beyond this — and its link to consciousness (which it seems had not been considered before, which is exciting!). I now want to very briefly look at how this idea works with Aquinas’s idea of forms (taken from Aristotle) and his philosophy of mind.


The form of a thing is simply the account of the “what-it-was-to-be-that-thing”. Eg a human is a bipedal animal that can talk. It’s those properties that make X to be X.

We should be careful not to reify it into something it’s not: it’s not a ghostly separate substance that’s added to the thing to make it what it is. It’s not exactly a thing at all. It’s more like the definition of the thing. And it’s not one more part of the thing, so much as it’s the thing as a whole. In the example of a bronze sphere, it’s the geometry of the sphere.

It’s counterpart is the matter that the object in question is made of. So a bronze sphere is made of bronze (its matter) and made into a sphere (its form).

Now considering the idea of forms from the perspective of OSR, there’s no difficulty in saying that forms are structures of relationships, as OSR says is true for all things. The account of X is the relations proper to X, that make X what it is, as X. So eg a house is a house because it is a man made habitation for humans – it is related to humanity as a product of human work, and as a home. These two relations create a structure of relations, and that relational structure is what we term a “house”.

The intellect, forms, and the brain

Aquinas tells us that, “a thing is known in as far as its form is in the knower” (ST I Q75 a5). It’s a great insight that knowledge of a thing is a question of its form being in the intellect. To know X is to comprehend its essential X-ness. We can say that X exists in the mind. But we have knowledge of things such as fish, and yet we know that there are no fish actually materially swimming around in our brains, such that a neurosurgeon might take one out and have it for dinner. So we can reasonably assert that things exist within the mind according to their forms, and therefore immaterially.

Aquinas took this point and reasoned from it that the intellect itself must be immaterial. But I think this step is unnecessary if you accept the claim that the form of a thing is simply the structure of its relations, and understand that it’s possible for these same structures to be instantiated in various mediums, eg the matter and or processes within the brain. The structures within the brain are capable, I suspect, of taking on any structure that is logically possible, including the structure of forms.

Let me know what you think!


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