Scepticism and Justification

A. C. Grayling

I

The study of scepticism might be said to define epistemology. As the enquiry into the nature and sources of knowledge, epistemology's two fold concern is to identify and explicate the conditions whose satisfaction will amount to knowledge. Familiarly, one of these crucial conditions is justification. The problems facing the justification of knowledge-claims can best and most powerfully be described by framing them as sceptical challenges, meeting which – if possible – will certify that we are at least sometimes indeed entitled to make claims to knowledge.

Given the centrality of the question of justification in epistemology, and given that the work required of justification is defined by sceptical challenges to our claims to know, it is therefore essential to get the nature of scepticism itself right. My task in what follows is to describe the anatomy of scepticism correctly. At the end I remark that the anatomisation I offer suggests what form a response to scepticism should take.

II

Despite traditional appearances, scepticism is not well described as doubt or denial, nor is it properly understood without limitation of subject matter. Rather, it is best and most sharply characterised as a motivated challenge, in a specified area of discourse, to the makers of epistemic claims in that discourse. The challenge is to defend the grounds offered in support of those claims so that the concerns embodied in the sceptic's motivation for issuing the challenge will be met. His motivation consists in the battery of familiar sceptical considerations which, in the tradition of debate on these matters, have come to be called sceptical 'arguments'. One of the main points I urge is that this is a misdescription. Unravelling this characterisation gives us our anatomy of scepticism.

First, it is a mistake to think of scepticism as consisting in an agniology, that is, a thesis to the effect that we are ignorant either globally or in some region of enquiry. Certain early forms of scepticism (notably the Pyrrhonian) appeared to take this form, but the briefest reflection shows that global agniology is trivially self-defeating (if we know nothing, then we do not know that we know nothing), while local agniologies must themselves consist in positive claims to the effect that we are ignorant in the given sphere, and any positive claim can itself be challenged for its justification. Of course, weak forms of local agniology – which remind us that our knowledge in given regions of enquiry is incomplete, or provisional, and that a healthy attitude of open-minded scrutiny must greet each new claimed advance in them – are perfectly acceptable (and perhaps reflect moderate Academic scepticism, advanced in antiquity in opposition to Pyrrhonism on the grounds that life must be lived). But they do not amount to scepticism in the sense important in epistemology; in this guise they amount merely to injunctions to proportion assent to grounds – in short, to be rational.

But not only is scepticism not well described as the thesis that we are ignorant, it is not even well described as an attitude of doubt. Such an attitude would be premised on the view that there is something inherently suspect about our epistemic practices, a presumption which, when it does not verge on being self-defeating after the manner of global agniology, loads the dice against enquiry before it has offered what it can claim in its support. There is a colloquial use of ³sceptic² to denote one who is very hard to persuade even about the most evident matters – a stance that commits the opposite sin to credulity or too ready assent – which this characterisation conveys. But there is as little reason to think in advance that knowledge claims are by their nature largely doomed as to think that they are all justified. Our interest lies in separating the wheat from the chaff; and this we expect an examination of properly characterised scepticism to help us do.

It does so when we recognise scepticism in a given domain of enquiry as a motivated challenge to make out the justification offered for epistemic claims made in that domain. The best sceptic does not himself claim anything; he asks for a defence of our justificatory practices in the light of certain important considerations relating to them. These important considerations concern contingencies affecting our ways of getting, testing, employing and reasoning about our beliefs. The contingencies in question are familiar from the traditional epistemological debate: they relate to the nature of perception, the normal human vulnerability to error, and the existence of states of mind – dreaming, hallucinating, being deluded, and the like – which can be subjectively indistinguishable from states that we normally take to be appropriate for reliably forming and employing the beliefs in question. By invoking these considerations the sceptic motivates his request to see the support that can be adduced on behalf of claims made in the course of standard epistemic practice. His invocation of them does not support an agniology, nor does it license doubt beyond the reasonable norm in enquiry. If the sceptic's aim were truly to establish either of these two positions, adducing these contingent facts about perception, vulnerability to error, and the rest, would not succeed in doing so without further strong argument to the effect that these knowledge-defeating contingencies are universal, unavoidable, undetectable (and so on), which would be an extremely hard case to make, if only for the reason that it would require of us that we never know what we are talking about when we use such expressions as ³knowledge², ³justification², ³truth², and the like.

But putting matters this way also shows that scepticism is not to be rebutted by saying that we should begin with confidence in our standard epistemic practices, and require the sceptic to show special reason why on any given occasion he himself has justification for mounting a challenge. (Such might be the strategy, for example, of a ³relevant alternatives² rebuttal of scepticism.) The point about the contingent facts which the sceptic can adduce is that they illuminate the (at least prima facie) defeasibility of our epistemic practices, and thereby show that there is an onus on us to rule them out when we advance knowledge-claims, or at least to accommodate them, in ways which do not defeat the project of getting knowledge or at least, well-justified belief.

III

It is important to see how the traditional sceptical arguments conform to this diagnosis of scepticism as challenge rather than claim. One characteristic pattern of such argument is drawn from a set of considerations about error, delusions and dreams. Another trades on facts about perceptual relativities and the fact that our cognitive capacities pay a constitutive role in the nature of our experience. Empiricist views suffer particular problems from considerations relating to the nature and limitations of perception, and here the pattern is at its clearest. The best current empirical account of perception tells us a highly complex causal story, beginning with impingements by the environment on our sensory surfaces and ending with the full richness of phenomenal experience and its sequelae in thought and memory. How this remarkable transaction occurs is still mysterious to science and philosophy. But occur it does; and the causal complexity of the process appears richly to invite sceptical challenge. From the subject's viewpoint there might be no way of telling the difference between normally and abnormally caused experience.

The pattern is: if one knows that p, then nothing is acting to defeat one's justification to claim knowledge that p. But one can seem to oneself fully entitled to claim to know some p and in fact lack that entitlement, as the foregoing considerations show. An alternative characterisation is to say that we can have the best grounds for claiming to know that p, and yet p can be false; the conjunction of the set of propositions asserting the grounds for p with the negation of p is not a contradiction. Employing this latter idiom captures the underlying logical structure of the defeasibility of epistemic practice, and the contingency of what makes it so. So our claims to knowledge are in need of better grounds than we standardly take ourselves to have. We must, in short, find a way of defeating the defeaters.

IV

One immediate result of grasping the challenge pattern of scepticism as exemplified in these ways, is to note that sceptical considerations are not correctly described as 'arguments'. Sceptical mooting of the familiar considerations is much more like Wittgenstein's 'assembling reminders', by itself enough to show that there is work to be done in justification of epistemic practices. And it follows immediately that if sceptical considerations are neither claims of an agniological tendency, nor arguments purporting to establish an agniology or even just enquiry-undermining infective doubt, then obviously it is a mistake to respond to scepticism as if it were either. In particular, it is a mistake to try to respond to sceptical challenge piecemeal, taking each of the considerations a sceptic might adduce one by one and offering a demonstration that it does not unseat the epistemic project – for the considerations adduced by the sceptic have merely maieutic status, and it is a disjunction of them – or any one of them by itself – which prompts the thought that epistemology has positive work to do in support of justification.

The point can be well illustrated by considering (just as an example) Gilbert Ryle's well-known attempt to refute the argument from error by using a 'polar concept' argument in response. There cannot be counterfeit coins, Ryle observed, unless there are genuine ones, nor crooked paths unless there are straight paths, nor tall men unless there are short ones – and so on. Many concepts come in such polarities, a feature of which is that one cannot grasp either pole unless one simultaneously grasps its opposite. Now, 'error' and 'getting it right' are conceptual polarities. If one understands the concept of error, one understands the concept of getting things right. But to understand this latter concept is to be able to apply it. So our very grasp of the concept of error implies that we sometimes get things right.

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