Knowledge, concept of

8. The epistemic principles and scepticism

Scepticism – the view that we lack knowledge in those areas commonly thought to be within our ken – comes in many varieties. The most extreme view is global scepticism. It holds that we have very little, if any, knowledge. That view seems preposterous at first glance. Indeed, some epistemologists think that any theory that leads to global scepticism should, ipso facto, be rejected (see Commonsensism; Scepticism). Yet there are many arguments for global scepticism that are difficult to answer. In addition, more modest forms of scepticism about particular subject matters (for example, other minds or the future) have been developed. But since the more modest sceptics employ strategies similar to those employed by the global sceptics, I here consider only the most extreme form of scepticism – global scepticism (see Other minds).

We have already seen the basis for one such argument for global scepticism that can be gleaned from the Pyrrhonians, namely:

There are at least four possible responses to this argument: (1) the foundational, basic propositions are not arbitrary; (2) coherentism does not necessarily lead to question-begging arguments; (3) requiring infinitely many reasons for a belief does not entail that a belief cannot be justified; (4) not all knowledge entails having reasons. All but (3) have been systematically developed by epistemologists.

Pyrrhonism does not rely directly upon the epistemic principles discussed in the preceding section. But there are other important forms of scepticism that do. Consider this argument that can be traced to Descartes (see Descartes, R. §4):

Premise 1 is a clear instance of CLO-P. Since the argument is valid (if the premises are true, the conclusion must be true), there are only three plausible responses: (1) CLO-P is false; (2) the second premise is false; (3) the argument begs the question. Responses (1) and (2) are relatively easy to envisage; the third is not so obvious. Roughly, the argument goes as follows: since one of the potentially available grounds for my being justified in believing that I am not in a sceptical scenario is any proposition that entails that I am not in such a scenario, every good argument for the second premise would have to establish that I am not justified in believing that there is a table before me. But that, of course, is the very conclusion.

It is important to note that there is an apparently similar argument for scepticism employing the stronger epistemic principle, ET-P:

Of course, it is open to epistemologists to deny ET-P. Since one can deny ET-P without abandoning CLO-P (because CLO-P does not entail ET-P), that certainly seems to be a strategy worth considering. The discussion in the next section provides additional reasons for considering that strategy.