forum 1, week of Jan 8, Dretske
Question 1: The claim is that epistemic operators are not fully penetrating to all consequences of them being zebras. If we know that they are zebras we do not necessarily know that they are not painted mules. And yet to 'know' something may be said to be a very strong claim according to this picture. If I had not considered that they were painted mules, then as far as my epistemic state is concerned, they could be painted mules. And if it is possible in this epistemic sense that they are painted mules, then I can't claim to know, in that same sense, that they aren't, and therefore I can't claim to know that they are actually zebras.
Dretske views this to be a mistake. It does not follow from the fact that we had not considered them to be painted mules that we don't know that they are zebras. We can know that they are zebras and not know that they are not painted mules.
If it were the case that we were being duped, then we wouldn't have known that they were zebras because the claim that they are zebras would be false. It is surely possible that they are animatronic displays, that they are painted mules, that I am having a dream, that a higher being is deceiving me, etcetera. But is the point of claiming that we know something to show that nothing of the sort is possible? Some alternatives can't even be attached to a probability, in the case of there being a deceiver, and yet the answer to whether or not there is a deceiver is entirely relevant to the question of whether we know there are zebras(or anything at all for that matter), and there is no way to exclude it. Would us not considering there being a deceiver imply that we didn't know that there were zebras instead of painted mules? I don't think so. But It's a very difficult question and I don't know how to answer it without getting into the nitty gritty details of what counts as relevant information.
I do think that knowledge has weaker conditions that we like to let on. When we claim to know something, we tend to have a set of positive claims to back it up, even though some not-claims that are not even thought about are entirely relevant and don't allow us to strictly know anything at all until they are known. Hope that makes sense.