Why Do People Worry about Whether Intuitions Are Evidence? (by guest blogger Jonathan Ichikawa)
I wanted to say a little more about philosophical methodology and naturalistic challenges to a priori investigation. A key point of dispute between, let's call them, naturalists and rationalists, seems to involve the proper role of intuitions in philosophical methodology.
Again, I'll start by describing a hypothetical disagreement, running the risk of caricaturing the arguments in question. If that's what I'm doing, it will be instructive to see how the real views are different from my presentations of them here.
Archie: Consider twin earth, which is kind of like regular earth, but where there's no H20. Instead, there's this other stuff XYZ, which is not H20, but is superficially very similar to H20. It's clear and quenches thirst, etc. Introspecting, we discover in ourselves the rational intuition that XYZ is not water. Intuitions are good evidence; therefore, XYZ is not water. Therefore, externalism about content is true.
Eddie: It's not rational to blindly treat your so-called "rational intuitions" as evidence. We can't calibrate our intuitions to check their reliability, and it's totally mysterious how it is that they could be reliable. We shouldn't just trust them. We should go administer surveys instead. If we want to know whether XYZ is water, we have to go see how the folk use the word 'water'.
In my last dialogue, I claimed there was no real disagreement, even though they clearly thought there was. This time, I think they're both agreeing to something silly. According to traditional methodology, our intuitions are supposed to be evidence? Why? I think the most attractive position is this one: Experimental Eddie is right that we shouldn't treat our intuitions as evidence, but both he and Armchair Archie are wrong that traditional methodology commits to intuitions as evidence.
When I judge that that stuff on twin earth is not water, how shall we understand the reasoning I run through? Not, I suggest, like Archie said:
(1) I have the intuition that XYZ isn't water. (introspection)
(2) So, XYZ isn't water. (1, principle about intuitions)
(I'm omitting (3) So, content externalism.) Instead, we can understand the reasoning as not involving any premise about intuitions, or based on introspection, at all:
(3) All and only H20 is water.
(4) XYZ isn't H20.
(5) So, XYZ isn't water.
This argument is valid and plausibly represents the reasoning we go through to ourselves. And no premise is based on introspection or a claim about an 'intuition'.
Someone will say: "but the only way you could know (3) is by intuition." Since I don't know what intuitions are, I won't try to evaluate that claim; the point is that (3) is something that everybody should agree we can know, and that therefore its invocation in this judgment about a thought experiment shouldn't be problematic. (Do you doubt that we know (3)? That's to doubt whether we can recognize the possibility of fake water.)
This argument, of course, is a posteriori, because premise (3) is. But there's an a priori version of it, too:
(3') All and only things that are F are water, where 'F' stands for whatever it is that it turns out makes up water.
(4') XYZ is not made up of F.
(5) So, XYZ isn't water.
Whenever possible, we should avoid putting argument in terms of 'intuitions'. I suggest that this is almost always the case.