In the previous post I mentioned that Williamson clearly opposes in chapter 7 a broadly psychological conception of philosophical evidence. But it isn’t exactly clear just what his target is. At times he seems to be arguing against psychological evidence _ever_ being philosophically worthwhile. For example, consider the following batch of quotes.

bq. “For now I face the challenge of arguing from a psychological premise, that I believe or we are inclined to believe the Gettier proposition, to an epistemological conclusion, the Gettier proposition itself. That gap is not easily bridged.”

bq. “Since psychological evidence has no obvious bearing on many philosophical issues, judgment scepticism is also encouraged in ways that do not depend on the consequence fallacy.”

bq. “In explaining why we have intuitions, analytic philosophy has a preference for explanations that make those intuitions true over explanations that make them untrue, but the justification for that preference remains unclear”

In those quotes his opponent seems to hold the relatively weak view that psychological evidence can (sometimes) be useful evidence for philosophical conclusion. But other times he seems to take his opponent to be the person who holds the much stronger view that only intuitions are evidence. For instance, he says

bq. “One result [of EN] is the uneasy conception many contemporary analytic philosophers have of their own methodology. They think that, in philosophy, ultimately our evidence consists only of intuitions.”

I think it’s hard to believe that’s really a widespread view in philosophy. Does Singer’s argument for vegetarianism rest (even ultimately) on intuitions about the nutritional value of a vegetarian diet? Does the well-known argument from special relativity against presentism rest on intuitions about whether special relativity is true? Nevertheless, Williamson does attribute it to many (unnamed) philosophers. And yet some of Williamson’s arguments seem directed particularly against this position. For instance, he says

bq. “Taken far enough, the psychologisation of philosophical method becomes self-defeating”

And he cites approvingly Joel Pust’s conclusion that it is self-defeating to hold that

bq. “Aside from propositions describing the occurrence of her judgements, S is justified in believing only those propositions which are part of the best explanation of S’s making the judgements that she makes”

Probably Pust and Williamson are right here, but it hardly tells against anything but a strawman version of the psychological view of evidence. Finally, Williamson objects to a version of Reflective Equilibrium that just attempts to get our intuitions into equilibrium with the following argument.

bq. “The reflective equilibrium account, as usually understood, already assigns a proto-evidential role to at least one kind of non-psychological fact. For it treats philosophers as relying on logical relations between theories and intuitions, in particular their consistency and inconsistency.”

The theme again is that we need some evidence other than intuitions, something that should be common ground. (For reasons I’ll suggest in the next post, I’m not sure this is a good argument for that conclusion though.)

We haven’t got very far by trying to characterise what Williamson’s opponent says. Perhaps it is better to look at his positive proposal for what is evidence in philosophy. We get one statement of what that positive conclusion.

bq. “Our evidence in philosophy consists of facts, most of them non-psychological, to which we have appropriate epistemic access.”

That, in conjunction with the quotes above, suggests he is defending the following three theses.

1. Not all philosophical evidence is psychological.
2. Having _p_ be part of your evidence requires appropriate epistemic access to _p_.
3. The intuition that _p_, or the fact that one has that intuition, is weak evidence, perhaps no evidence at all, that _p_.

A position that denied all three of those would clearly be among the targets of Williamson’s chapter. But that would be crazy, since (1) is obviously true. But a position like the one I sketched at the end of the last post, which was neutral on (2) and denied (3), would still seem to be at odds with the bulk of what Williamson says, and I think is meant to be among the positions ruled out by the considerations he raises.

Now such a position does not seem especially related to the sceptical positions that are the targets of sections 3 and 4 of Williamson’s chapter 7. But that’s as things should be. The question of what our evidence is doesn’t immediately settle the question of what knowledge we have. Taking perceptual evidence to be psychological might be a precursor to defending external world scepticism. But it might also be a precursor to adopting indirect realism. Of course Williamson, by accepting knowledge as evidence, has effectively ruled out classical forms of indirect realism, where we know about the world on the basis of purely phenomenal evidence. But that shouldn’t be presupposed here I think. A position that holds that psychological states, or facts about them, are often crucial evidence for us is opposed to the core doctrines of Williamson’s chapter, even if it is also opposed to some of his other opponents.