In week 2, we addressed the Gettier problem, which concerns the analysis of knowledge. Now we turn to another central question in epistemology, is knowledge attainable to begin with? Meeting the belief condition is easy, but meeting the truth condition may be impossible. Can you know that the external world and other minds exist? Can you know for sure that you are not the only minds that exists, and that other minds and the external world are merely your confabulations? If you cannot rule out such skeptical alternatives, are there any simple basic things you can establish as certainties, like you have hands or are watching this clip? Earlier, we credited the cult with having defined the problem of skepticism by means of skeptical alternatives. The logical possibility of the dream and that of the evil demon constitute skeptical alternatives which are alternative explanations of our experiences that endanger whatever we think we know because we need to, but cannot rule them out for several reasons. Recall, for instance, the sensitivity condition of Nozick's true-tracking analysis. You cannot know that you are not systematically misled by an evil demon because if you were systematically misled by an evil demon, you would still believe that there is no evil demon. Let's develop a similar, but more recent example. Suppose you are the epistemic subject s, and that the proposition p that you know is that you have hands. Enter the skeptical alternative. It's conceivable and thereby at least logically possible that you are not a person of flesh and bones, but rather a brain in a vat, or BIV, in which all the experiences that you have are artificially produced by electric stimulation. Of course, you don't really believe you are BIV, but you can't exclude the possibility either. So far so good. It's possible that you know that you have hands and that you do not know that you are not a BIV at the same time. However, the skeptical challenge arises from closure. Here, the conditional assumption that if you know that you have hands, then you know that you are not a BIV. The underlying idea is that knowledge is factive. You can only know that you have hands if it is a fact or if it's true that you have hands. In other words, you can only know that you have hands if it's true that you are not a BIV but rather a person of flesh and bones, and hence, if you really know that you have hands, then it is implied that you are in a position to know that you are not a BIV. The argument of the skeptic is that being able to know that you are not a BIV is required for you to know that you have hands. Since you cannot know that you are not BIV, you cannot know that you have hands either. According to the skeptic, this point generalizes whoever the epistemic subject s is and whatever the belief p is, and whatever the skeptical alternative under consideration is, s cannot know that p, because to know that p, s should be able to exclude all skeptical alternatives to p, but s cannot exclude any of them. In the face of the skeptics' arguments, we can defend talk about knowledge by drawing attention to the role and importance of context. Normally, we know that we have two hands. The Earth is round and 2 plus 2 equals 4. However, according to contextualism, when skeptical alternatives are made salient to us, we no longer know those things. Before you started to watch this clip, you were probably not even aware of the possibility of you being a BIV, and so you knew that you have hands in that earlier context. However, by introducing the skeptical alternative in this clip that you might be a BIV, the context has been changed. Now in this new context, the skeptical alternative that you might be a BIV has become salient, now you realize that you cannot exclude the possibility of the skeptical alternative, and as a result, you no longer know that you have hands in this present context. We can also defend ourselves against the skeptics' arguments by appealing to context in a slightly different way. We justify our claims all the time by adding reasons for these claims. To adopt a famous example from Austin, when someone claims that the bird is a goldfinch, they might refer to its redhead as typical of such a goldfinch. In response, someone else may wonder whether the bird is a woodpecker instead of a goldfinch, pointing out that a woodpecker too has a redhead. This is what we call an appeal to a relevant alternative. In the context of a bird in your garden, it makes sense to discuss whether it is a woodpecker or a goldfinch. But it would be really strange if someone would wonder whether it is a mechanical or a stuffed birds because such alternatives are not relevant in that context. According to the relevant alternatives approach, to make knowledge claim, an epistemic subject should only be able to exclude all relevant alternatives, and which alternatives are relevant is determined by the context at hand. However, there are hardly any contexts in which skeptical alternatives are relevant. As a result, skeptical alternatives hardly ever legitimately challenge knowledge claims.
