## Sellars and the Philosophy of Physics

In a letter to Chisholm, Wilfred Sellars wrote:

Thus, while I agree with you that
‘. . .’ means – - -

is not constructable in Rylean terms (‘Behaviorese,’ I have called it), I also insist that it is not to be analyzed in terms of
‘. . .’ expresses t, and t is about – - -.

My solution is that “‘. . .’ means – - -” is the core of a unique mode of discourse which is as distinct from the description and explanation of empirical fact, as is the language of prescription and justification.

Although Sellars was concerned with the philosophy of mind, there is something important here for philosophers of physics to learn as well. A major activity of physics is the collection of empirical facts. Another is the prediction and justification of these facts. But the activity of investigating meaning is a distinct activity altogether. This last activity includes much of what concerns the philosophy of physics, when it is done well.

Whether it be causation, equivalence, gauge, prediction, or simultaneity — among many examples — I think much of what distinguishes philosophy of physics from physics is a central concern with the (particularly philosophical) activity of explicating meaning.

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## 5 thoughts on “Sellars and the Philosophy of Physics”

1. Jonathan Livengood

I have a lot of questions. First, why do you say that what Sellars is interested in here is philosophy of mind? Isn’t he pursuing a question in philosophy of language, namely, should we have be reductionists about “meaning”? (Specifically, he appears to deny that meaning is reducible to Behaviorese, whatever that is.) Second, why do you think that much (how much, where, and why) of what *distinguishes* philosophy of physics and physics is explication of meaning? Why not just a difference in the subject matter of concern, e.g. physicists might be less concerned with foundations or interpretations of operationally adequate theories than philosophers of physics. Third, what is the connection between Sellars’ claim that meaning (or more precisely, statements of the form < "..." means --->) forms the core of a distinct (non-reducible) mode of discourse on the one hand and your claim that philosophers of physics are often interested in explicating meaning? Is the claim that explication of meaning for a philosopher of physics is not like description or explanation? Incidentally, is Sellars claiming (1) merely that meaning is as far away from description/explanation as is prescription/justification, (2) that meaning is different from both description/explanation AND prescription/justification, or (3) that meaning has something in common with prescription/justification in virtue of which it is distinct from description/explanation?

2. Bryan

why do you say that what Sellars is interested in here is philosophy of mind?

Obviously it’s about language too. But the letters are called “Intentionality and the mental.” Why split hairs?

Why not just a difference in the subject matter of concern, e.g. physicists might be less concerned with foundations or interpretations of operationally adequate theories than philosophers of physics

That just distinguishes operationalists from non-operationalists. We can do better than that.

Is the claim that explication of meaning for a philosopher of physics is not like description or explanation?

Yes.

Incidentally, is Sellars claiming…

That seems to be right. Hope that helps! — BR

3. Jonathan Livengood

I really didn’t think I was splitting hairs on the language/mind thing, but maybe I was. Was Sellars saying that meaning has something special to do with intentionality? (I wasn’t picking that up from the excerpt, but I wouldn’t be too surprised if it’s clear from the rest of the letter.) If so, what? If not, what is the connection to philosophy of mind?

I think you’re focusing too much on the example (that “physicists might be less concerned with foundations or interpretations of operationally adequate theories than philosophers of physics”) and not really addressing my question. Why do you think that much (and how much) of what distinguishes physicists and philosophers of physics is explication of meaning? You seem to think that this activity is a hallmark of philosophy. Increasingly, I don’t feel like I really know what philosophy is supposed to be or what philosophers do. So, I’d be really glad to see you expand and expound a bit on this!

Okay, what is it about explicating meanings that is different from, say *describing* a language game or *explaining* why people (physicists?) say the things they say?

Finally, I offered three competing interpretations of the Sellars passage. What do you mean by replying, “That seems to be right”?

4. Bryan

I think the best way to know what philosophers of physics should be doing is to look at great philosophy of physics. I don’t think it’s helpful to give a general definition. You know great philosophy of physics when you see it.

I do find it helpful to note some examples of great philosophy of physics. Just off the cuff: Healey’s work on gauge; Earman’s work on determinism; Maudlin’s work on locality; Norton’s work on the equivalence principle; Malament’s work on simultaneity; Ruetsche’s work on unitary inequivalence; Greaves’ work on CPT; etc etc.

As it happens, I think that one nice way to characterize what’s going on in these particular works is to note that they involve “explication of the meaning of a foundational concept in physics.” Of course, there are certainly other things that philosophers of physics do. But a lot of good work comes out of that particular activity, and I think that’s worth noting.

5. Bryan

Here’s an example about the description-explanation-meaning distinction. Suppose we have a rock freely falling toward the earth. Someone might give a precise description of the phenomenon. Someone else might give an explanation of it, say in terms of bodies following geodesics through curved spacetime.

But suppose we ask, what does it mean for a rock to be freely falling? This is the kind of question that might interest a philosopher of physics. It identifies a central concept in physics (bodies in free motion), whose meaning is often unclear. And it seems to me that a lot of good work comes on focusing on such questions.