In previous posts (such as this one and this one), I have sometimes alluded to the philosophy of structural realism. Structural realism says that we are unable to know the intrinsic character of the world outside our minds, although we are able to know a great deal about the structure of that world, especially its causally relevant features. Thus, we can know what we need to know to survive and thrive in our environment, we just can’t know what it is like intrinsically. For instance, we cannot know whether the surfaces of objects have the colors they appear to have in our visual perceptions of them or the hot and cold qualities we feel them to have, etc. Even the intrinsic character of spatial relations may not be as it appears to us. Still, the structure and dynamics of all these things is accessible to us—which is fortunate, because that is what matters for successful action.

I think structural realism is true and indeed inescapable. However, discussion of it in philosophy today is blighted by obsession with something called “Newman’s Objection,” after Max Newman, a Cambridge mathematician who published an important critique of Bertrand Russell’s version of structural realism as advanced in Russell’s book, The Analysis of Matter (1927). In my view, Newman rightly identified an important flaw in Russell’s structural realism, but not in structural realism per se, which has many options available for removing the difficulty. Unfortunately, many philosophers today, including many structural realists, treat Newman’s Objection against Russell (and subsequent formulations essentially like Russell’s), unless it can be refuted somehow, as a decisive refutation of structural realism itself. The result has been a lamentable lack of progress in developing the implications and insights of structural realism.

In what follows, I will explain how I think Newman’s Objection should best be handled and why it is a paper tiger. However, I have chosen to do so via an analysis of a much more well-known argument that in its essentials is practically identical with Newman’s, namely Hilary Putnam’s “model-theoretic argument” against the possibility that the terms of natural language or of our thoughts and percepts can have determinate referents in the mind-independent world.

This means that “what follows” is going to be a long haul! If anyone wants to read the whole paper in one fell swoop, it can be found here. Here at PoT, I will send it out in five installments, of which this post is the first. In this first installment, I begin with Putnam’s own warm-up exercise: his argument that a “brain in a vat” would be unable even to think that it was a brain in a vat. (To skip to the second installment, click here.)