By Kelly Trogdon
This is my first post here – thanks Gualtiero for inviting me.
As I read Chalmers’ “Does Conceivability Entail Possibility?” (2002), he claims that a state of positive conceivability is positive in virtue of involving a “positive intuition” of a situation, and to have such an intuition is just to represent a situation, judging that it verifies a proposition. The claim is that you positively conceive P when you represent a particular situation, judging that it verifies P, while to negatively conceive P is just to judge that ~P is not a priori. (Here I’m glossing over various distinctions that come up in the paper that aren’t relevant to what I’m going to say.)
Let P be the proposition expressed by “Situation S is F”. Suppose that you negatively con
ceive P (i.e. you judge that ~P is not a priori) and then judge that S, qua situation with F, verifies some proposition P*. By Chalmers’ lights, your state of conceivability here is positive. I don’t think, however, that we should be comfortable with this result. It’s true that in this case you judge that S and P* stand in a certain epistemic relation, but it’s unclear why this alone should engender or require anything like a “positive intuition” of S, provided that I correctly understand what we’re trying to capture here.
Let’s say that you perceptually imagine P just in case you form a mental image of a situation S (a representation of S relevantly similar to how you would represent S in perception) and judge that S verifies P. I think I understand how mental images in this sense are positive, independently of the role they play in verification judgments. So I likewise think I understand why it is that perceptual imagination should count as a form of positive conceivability.
What I struggle with, however, is non-imagistic positive representation in this context. Assuming that such representation is absent in cases of negative conceivability, our example above shows that to form a non-imagistic positive conception of a situation is not merely to form a non-imagistic representation of that situation that you take to verify a proposition.