The primary criticism of Quine’s naturalisation of epistemology project is that he was attempting to abandon the normative component of epistemology entirely. Many epistemologists would say that this approach is a wrong move in itself. Jaegwon Kim argues that it's not even possible without giving up on epistemology itself.
Kim actually sees Quine’s ‘evidence’ - or anyone else’s for that matter - as justification or justificatory in nature. Something works as evidence because it effectively justifies a theory or whatnot. Not only that: there will be normative factors which determine want counts to us as evidence (as well as why things don't count as evidence). There may also be normative factors or judgments which have led us to find what we now take to be evidence.
For example, not accepting anything a mad scientist takes to be evidence for X to actually be evidence for X.
Quine himself often talks about evidence in his naturalisation project, yet Kim argues that
"evidence itself is a normative concept, distinct from and irreducible to the naturalistic concepts employed in science, e.g., the concepts of stimulation, causation, law, etc". (289)Ordinarily one wouldn't really think of such a scientific predicate as ‘evidence’ as being a ‘normative concept’. So what does Kim mean by this? Firstly, he used the word ‘evidence’ is this context:
"Traditional epistemology asks what makes certain states, certain experiences and beliefs, evidence for other beliefs." (289)This isn't very helpful because Kim tells us how the concept [evidence] was used in traditional epistemology; though he doesn’t tell us what traditional epistemologists, or what he, means by 'evidence' and why it is indeed a normative notion. He seems to be talking not about the relation of beliefs, ‘certain experiences’ and their relations to the world; but the relation of beliefs and experiences and their relations to ‘other beliefs’. Thus it is, perhaps, an internalist account. It's also logical in that Kim is referring to the evidential or logical ‘links’ between beliefs and beliefs - not between beliefs and the world. That is, the world itself can't be taken as evidence. Beliefs themselves must be taken as evidence. And beliefs have a normative dimension.
This is also Donald Davidson’s position in that he argues that the world - or an aspect of the world - doesn't provide evidence for a belief: only another belief can do that job. This seems to be both a holist argument and an argument against Quine’s position on what he calls ‘sensory stimulations’ (amongst other things).
In any case, according to Kim, ‘empirical psychology’ doesn't offer us anything about these logical or evidential relations between beliefs and beliefs; but only between our ‘meagre input’ (i.e. Quine’s sensory stimulations) and our ‘torrential output’ (i.e. our assertions or beliefs). Another way of putting all this is to say that the naturalised-epistemology approach (or the empirical-psychology approach) is purely descriptive in nature in that it tells us what goes in (the head) and then correlates it with what comes out (of the mouth). Though if it only does that, then it tells us nothing about ‘what confers positive epistemic value’ (289). That is, why is this evidence for that belief and is it good evidence? Not: X goes in and Y comes out.
I mentioned Davidson a moment ago and his stress on beliefs rather than on sensory stimulations and suchlike. Kim himself offers a
"Davidsonian argument for the claim that Quine is not even entitled to speak of naturalised epistemology as investigating the ancestry of beliefs". (289)Presumably this is because Quine would talk in terms of sensory stimulations being the ancestors (as it were) of beliefs. Though, as I've just said, Davidson argues that only other beliefs can be the ancestors of yet further beliefs. Not only that: if we see beliefs - rather than (mere) sensory stimulations - as being primary in the epistemological project, then
"the identification of beliefs is possible only on the assumption that one’s subjects are rational, where rationality here is normative and includes epistemic rationality". (289)That is, one must employ Davidson’s ‘principle of charity’ when analysing the beliefs of one’s subjects. And if we do that, we must assume that our subjects are - at least to a degree - rational. Rationality (or being rational), according to Davidson, is a normative notion because we must choose what constitutes rationality in that there's no purely scientific answer as to what rationality is. And the very assumption of a subject’s rationality is itself a normative move because he may well be mad. If the subject were mad, he wouldn't be the subject of an epistemological enquiry and perhaps wouldn't even be a person in the first place.
So various normative factors are creeping into the epistemological project all along the line. Even talk of ‘sensory input’, ‘sensory stimulations’ and ‘causal mechanisms’ between assertions and what the assertions are about can't erase the normative from the picture, at least according to Davidson and Kim.
Kim goes further than all this.
It's a simple fact, to Kim, that all epistemic properties are normative properties. So if naturalised epistemology gets rid of the normative, it also gets rid of epistemology. Thus naturalised epistemology mustn't be, well, epistemology at all.
Perhaps this is no surprise because Quine himself says that epistemology is a ‘branch of psychology’, which is itself ‘a book in science’. However, if epistemic properties are normative properties, and normative properties are supervenient (as Kim states), then epistemic properties must supervene on "certain non-epistemic, ultimately non-normative, properties" (289). So Kim’s position is far from being, say, Cartesian or internalist in nature and one may also say that it's also - to some degree at least - naturalistic in that epistemic properties must supervene on what is naturalistically kosher. However, this is also a question of whether or not supervenience itself (or its acceptance) is naturalistically acceptable.