I agree, of course, that someone can "get" the logic of an argument w/o accepting the conclusion b/c he or she doesn't accept the premises.  That could be an explanation of how a non-believer in evolution passes an evolution exam.  Maybe that was Aidan in the Hermann study.

But it clearly wan't Krista, right?  She indicated (or so it seemed to me) that she planned to use evolutionary science as a veterinarian while still "disbelieving" it as someone holding a religious identity.  It would make no sense for her to do that if she rejected the premises of the "logical deductions" that evolutionary science, for her, comprised.  

Also, I wonder if we want to think about the issue here as "knowing" while "disbelieving" (even though I have myself done that at various points).  

I know the standard philosophical definition of "knowledge" is "justified true belief," in which case one clearly can't have knowlege w/o belief.

But we also use "knowledge" to refer to "understanding" or "comprehension" all the time -- in which case I don't think the term connotes "accept as true" or "believe."  This is pretty typical use of "knowledge" in science.  Newton enlarged scientific "knowledge." Einstein knew Newtonian mechanics but didn't "believe it" (e.g., didn't believe that gravity operates instantaneously); disbelief of the scentific knowledge associated with Newtonian mechanics is what motivated him to generate his relativity theories.  He also didn't beleive quantum mechanics-- but surely he knew everything there was to know about it, including all the evidence in support of it.

Do you think of this as akin to the logic example?  It seems odd to me to think that we accept that scientists can "disbelieve" what is identified as the current state of scientific "knowledge" because what science accepts as "known" are merely the conclusions of deductive syllogisms indpendent of the truth of their premises.  Indeed, science says that what counts as "knowledge" must be ground in valid inference from observation-- i.e., empirical evidence.... But it's fine to go ahead & disbelieve it, too, so long as one agrees that whatever it is one "believes" instead is something the truth of which depends on adducing that sort of evidence too! 

Why not leave aside how to define or conceptualize "knowledge" w/o respect to "belief" & just say, What are we to make of someone who proclaims simultaneously to believe" and "not believe" some factual proposition?

Either that individual is engaged in self-contradiction or we are using a mistaken criterion of identity in individuating the proposition in question.

It's reasonable -- empirically, logically, or "whatever" (to quote Krista) -- identity on "evolution" solely with respect to its factual referent (the natural history of human beings and other animals, or the prevailing scientific theory and supporting evidence for that natural history of it). In which case, Krista and Pakistani Dr are guilty of self-contradiction.

But the question is whether, psychologically & behaviorally, the objects of belief can be individuated in that way; do they have any existence independent of what they (along with supporting intentional states) enable people to do?

Manny is right: it is dense to say that people who accept that natural laws are deterministic and who don't waste their time on "humans excepted" provisos-- just as Krista doesn't for evoution -- are engaged in "self-contradiction" when they believe that human beings have free-will.  The beliefs in question don't have any meaning apart from the activities that are being enabled by them.  The philosophers who are puzzled or who insist that people who do this are guilty of "self-contradiction" are engaged in "metaphysics" in the pejorative sense.

We should wonder whether those who can't accept the Pakistani Dr and Krista are having the same problem.  Maybe not, but I wouldn't be surprised.