Epistemology

3. Scepticism

The contrast between normative and naturalized epistemology is apparent in the way in which each addresses one of the most crucial issues in epistemology, namely, scepticism (see Scepticism). Scepticism comes in many forms. In one form, the requirements for knowledge become so stringent that knowledge becomes impossible, or virtually impossible, to obtain. For example, suppose that a belief is knowledge only if it is certain, and a belief is certain only if it is beyond all logically possible doubt. Knowledge would then become a very rare commodity (see Certainty; Doubt).

Other forms of scepticism only require that knowledge be based upon good, but not logically unassailable, reasoning. We have alluded to scepticism about induction. That form of scepticism illustrates the general pattern of the sceptical problem: there appear to be intuitively clear cases of the type of knowledge questioned by the sceptic, but intuitively plausible general epistemic principles appealed to by the sceptic seem to preclude that very type of knowledge.

Another example will help to clarify the general pattern of the sceptical problem. Consider the possibility that my brain is not lodged in my skull but is located in a vat and hooked up to a very powerful computer that stimulates it to have exactly the experiences, memories and thoughts that I am now having. Call that possibility the ‘sceptical hypothesis’. That hypothetical situation is clearly incompatible with the way I think the world is. Now, it seems to be an acceptable normative epistemic principle that if I am justified in believing that the world is the way I believe it to be (with other people, tables, governments and so on), I should have some good reasons for denying the sceptical hypothesis. But, so the argument goes, I could not have such reasons; for if the sceptical hypothesis were true, everything would appear to be just as it now does. So, there appears to be a conflict between the intuition that we have such knowledge and the intuitively appealing epistemic principle. Thus, scepticism can be seen as one instance of an interesting array of epistemic paradoxes (see Paradoxes, epistemic).

Of course, epistemologists have developed various answers to scepticism. Within the normative tradition, there are several responses available. One of them is simply to deny any epistemic principle - even if it seems initially plausible - that precludes us from having what we ordinarily think is within our ken (see Commonsensism; Chisholm, R.M.; Moore, G.E.; Reid, T.). Another response is to examine the epistemic principles carefully in an attempt to show that, properly interpreted, they do not lead to scepticism. Of course, there is always the option of simply declaring that we do not have knowledge. Whatever choice is made, some initially plausible intuitions will be sacrificed.

Within the naturalistic tradition, there appears to be an easy way to handle the sceptical worries. Possessing knowledge is not determined by whether we have good enough reasons for our beliefs but, rather, whether the processes that produced the beliefs in question are sufficiently reliable. So, if I am a brain in a vat, I do not have knowledge; and if I am not a brain in a vat (and the world is generally the way I think it is), then I do have knowledge. Nevertheless, those within the normative tradition will argue that we are obliged to withhold full assent to propositions for which we have less than adequate reasons, regardless of the causal history of the belief.

Contextualism, mentioned earlier, responds to the sceptical problem in a way that does not fall neatly into either the normative or naturalistic tradition (see Contextualism, epistemological; Contextualism, epistemological, recent work on). There are many varieties of contextualism, but central to all of them is that the truth conditions of a sentence or utterance attributing knowledge to someone will vary from one context to another. Hence, the utterance ‘Sarah knows that the car she left in the parking lot is still there’ will be true in one context when the standards for knowledge are lower than they are in a context in which the standards are those approaching certainty. In such a high standards context, Sarah will fail to know. Thus, by extension, says the contextualist, both our ordinary claims to knowledge and the sceptical claims that we don’t have knowledge can be true because of variations in the contexts of the utterances. So-called ‘invariantists’ deny that there is such a contextual shift of the truth values of the utterances and, hence, they reject the contextualist solution to the sceptical problem.