Is Philosophy All in Our Heads?
In a 1998 essay, Alvin Goldman and Joel Pust distinguish between two approaches to philosophy, which they call the mentalist and the extra-mentalist. According to the mentalist, when we do the typical philosophical armchair-reflection thing -- when we think about, for example, whether XYZ on Twin Earth (which behaves like water but has a different chemical formula) is water or not, or when we think about whether a dude who doesn't realize he's in Fake Barn Country knows that the real barn he's looking at is a barn -- we are finding out something not about the world outside of us, but rather about our minds. We are finding out about our concepts. According to the extra-mentalist, in contrast, philosophical thought experiments aim to reveal something about the world beyond our minds -- something about the real nature of water and knowledge, perhaps, or about what is and isn't possible. Goldman and Pust endorse mentalism.
Mentalism has the following great advantage over extra-mentalism: Mentalism makes it clear how it's possible for philosophers to learn something from their armchairs. What they are learning is about their own minds. They're exploring their concepts. It's much less clear how reflecting in an armchair can deliver what the extra-mentalist wants, valuable information about the world beyond our minds. But there are two equally great disadvantages to the mentalist conception of philosophy. First, it trivializes the subject matter. Where we thought we were learning about the world -- about the nature of language, of knowledge, of the fundamental constituents of reality, of the morally good -- it turns out that we're only learning about our concepts of language, of knowledge, of the fundamental constituents of reality, of the morally good. A very different sort of thing. How disappointing!
The second disadvantage of the mentalist conception is this: It turns philosophy into a methodologically dubious species of psychology. If what we're really interested in is our concepts, is sitting in an armchair thinking about Twin Earth really the best way to go about it? Well, that's one way. But empirical psychology offers us a whole stable of other ways, including polling people about puzzle cases, studying reaction times, asking people to list features in terms of typicality, etc. Armchair reflection about weird possibilities, by people who generally have some theoretical skin in the game, does perhaps have something important to contribute to the study of human concepts, but at most it is one part of a larger enterprise that is probably best left in the hands of psychologists.
So I think we must have an "extra-mentalist" conception of philosophy. Philosophers are trying to learn, not just about what concepts our human minds happen to be stuck with, but about reality as it exists beyond our minds -- and within our minds, possibly beyond our conceptions. But then that forces us back to the question of how reflecting in an armchair about strange scenarios, which is a large proportion of what mainstream "analytic" philosophers do, puts us in touch with that reality. My thought is: It doesn't. Well, let me temper that just a bit. Armchair reflection gives us a preliminary take; it helps us develop and discover the consequences of the views that we have inherited or acquired through everyday experience. In those domains where such inherited, everyday views are well-founded (e.g., the behavior of middle-sized dry goods under moderate force, mundane social interactions), our armchair judgments are likely also to be well-founded. The further we get from the ordinary, however, the less we should expect such armchair reflections to be of value. And unfortunately, most philosophical thought experiments are far from the ordinary.