page 2 of Scepticism and Justification

Ryle assumed that the sceptic is claiming that, for all we know, we might always be in error. Accordingly his argument – that if we understand the concept of error, we sometimes get things right – is aimed at refuting the intelligibility of claiming that we might always be wrong. But of course the sceptic is not claiming this. He is simply asking how, given that we sometimes make mistakes, we can rule out the possibility of being in error on any given occasion of judgment – say, at this present moment. But the sceptic need not concede the more general claim Ryle makes, namely, that for any conceptual polarity, both poles must be understood, and ­ further and even more tendentiously – to understand a concept is to know how to apply it, and for it to be applicable is for it to be applied (or to have been applied). This last move is question-begging enough, but so is the claim about conceptual polarities itself. For the sceptic can readily cite cases of conceptual polarities – 'perfect-imperfect', 'mortal-immortal', 'finite-infinite' – where it is by no means clear that the more exotic poles apply to anything, or even that we really understand them. Taking a term and attaching a negative prefix to it does not guarantee that we have thereby grasped an intelligible concept.

However, like Descartes' 'dreaming argument' or any of the other familiar sceptical considerations, it is not required that they themselves be sustainable or defensible in any specially robust way. They are not claims; they are suggestions, considerations, examples, adduced to motivate the challenge.

These remarks imply that sceptical considerations, even if singly they appear implausible, jointly invite a serious response; which is what, centrally, epistemology seeks to offer.

VI

One reflex way of describing the anti-sceptical task of epistemology is (as both Descartes and Russell formulated it in classic texts ) to discover the grounds of 'certainty'. This too is misconceived. Certainty is a psychological state that one can be in independently of whether or not one knows or justifiably believes that p. The falsity of p is no barrier to one's feeling certain that p is the case. Religious beliefs, the conviction that a given horse will win the next race, and many similar instances, amply demonstrate this. The original conflation of the subjective psychological state of certainty with the possession of a secure basis of knowledge is an artefact of Descartes' way of constructing the epistemological task. In his view, the task was to provide a secure route to knowledge from a subjective origin, viz. the origin or viewpoint of the knowing subject's own private data of consciousness. From these subjective data a route had to be found, supported by the right kind of epistemological collateral, to a public world existing outside and independently of that consciousness. Since the knowing subject himself had to be able to sort the contents of his consciousness into those that merited being called knowledge, from those that did not merit the label – that is: since the knowing subject had to be able to be sure that these items were knowledge, whereas those were (say) merely dreams – the mark of knowledge from the subjective viewpoint was thus the nature of the psychological mode of its entertainment, viz. a feeling of certainty.

Nearly all of Descartes successors in epistemology, up to and including Russell and Ayer, shared this view that the starting point for epistemology lies in subjective experience, and therefore faced the same difficulty in securing the epistemic guarantees for at least some of that experience which would rebut sceptical challenges. As with Descartes himself, doubtless the conceptual elision between certainty as a psychological attitude and certainty as a property of foundational or otherwise indubitable truths played its part in this. But in any case, certainty is not the target in epistemology, and if it appears in the residue of showing how to meet sceptical challenges it will be because the kind of epistemic assurance thus provided has, as an expected epiphenomenon, that attendant psychological attitude.

VII

As noted, sceptical challenges inform us that we suffer an epistemic plight, namely, that we can have the best evidence for claiming to know that p, and yet be wrong. Scepticism thus demonstrates the existence of a gap between the grounds a putative knower has for some claim, and the claim itself. Traditional responses to scepticism take the form of attempts either to bridge or close the gap. The standard perceptual model, in which beliefs are formed by sensory interaction with the world, together with ratiocination upon the data thus gleaned, postulates a causal bridge across the gap as the basis of knowledge. Given the vulnerability of the bridge to sceptical sabotage, the causal story requires support of some kind.

So do other bridges over the gap – inferential ones, as (again for a prime example) in the Cartesian epistemological tradition. Descartes identified the epistemology's task as the need to specify a guarantee – call it X for the moment – which, added to our subjective grounds for our beliefs, protects them against sceptical challenge and thereby elevates them into knowledge. His candidate for X was the goodness (the goodness, not merely the existence) of a deity – for a good deity's goodness would ensure that it would not wish us to be misled by what appears to be evidence – so long as we use our epistemic endowments responsibly. The mere existence of a deity is insufficient; it might, as Descartes' own evil demon hypothesis suggests, be a mischievous deity, thereby guaranteeing the unreliability of our beliefs instead.

Some of those of Descartes' successors who accepted his starting point (henceforth, the Cartesian starting-point) likewise sought an X to support the inferences from subjective experience to an independent and objective world, but not all of them felt able to invoke a divinity for the task. Yet others sought not to bridge the gap but to close it; this was the strategy of Berkeley and of the phenomenalists. In Berkeley's view, problems arise from thinking that behind or beyond experience there is a material world, where 'material' is a technical philosophical term denoting an empirically undetectable substance existentially supporting the sensible properties of things. Berkeley rejected the concept of matter (he did not reject the existence of the physical world) on the grounds of its empirical undetectability and the fact that sensible properties can, qua experienced entities, only have as their substance what is capable of experiencing them, viz. mind – and thereby closed the putative gap between experience and the world, for the latter turns out to consist in the former.

The phenomenalists made a similar move, with the interesting and more complicated difference that whereas for Berkeley all existence is actual (because everything is always actually perceived by the divine mind), most existence for the phenomenalists is merely possible – for the world is a (logical, in Russell) construction out of sensibilia, by which is meant actual and possible sense-data. Thus all those things not currently perceived by anyone exist as possibilities of perception (in Mill: a physical object is a permanent possibility of sensation). In being committed to the bare truth of an infinity of counterfactual conditionals, phenomenalism is therefore less tidy than Berkeleian idealism, in which all counterfactuals (which have a use only for finite minds: ³if I were in my study I would see my books²) are cashed in terms of what is actually the case from the infinite mind's point of view. (It was once thought that one gets phenomenalism from Berkeley merely by subtracting god; this is incorrect – one has to add an ontology of possibilia and with it a commitment to the bare truth of counterfactuals.)

These gap-bridging or gap-closing endeavours all assume, more or less directly, the Cartesian starting-point, and their familiar failure to provide satisfactory responses to the sceptical challenge accordingly suggests, among other things, that there is something deeply suspect about that starting-point. In their different ways Wittgenstein and Dewey both argued that the epistemological enterprise should start in the public domain, not in the privacy of individual consciousness – Dewey nominates the participant perspective, Wittgenstein's private language argument appears to subvert the notion of a Cartesian starting-point altogether. It does so because a private language is what a Cartesian subject requires in order to discourse about the inner contents of his mental life. A private language, in Wittgenstein's sense, is one that is available only to one speaker, not as a contingent but a logical fact: no-one can share the language with that speaker even in principle. Wittgenstein's argument to the incoherence of this notion is this: language is a rule-governed activity, and one only succeeds in speaking a language if one follows the rules for the use of its expressions. But a solitary would-be language-user would not be able to tell the difference between actually following the rules and merely believing that he is doing so; so the language he speaks cannot be logically private to himself. It must be shared – and can indeed only be acquired, in the first place – in a public setting.

The anti-sceptical possibilities of the private language argument did not seem to be apparent to Wittgenstein himself, for later, in his notes 'On Certainty', he employs a more traditional response to scepticism, somewhat in the tradition of Hume and Kant, by saying that there are some things we simply have to accept in order to get on with our ordinary ways of thinking and speaking. Such propositions as that there is an external world, or that the world came into existence a long time ago, are not open to doubt; it is not an option for us to question them, because they constitute the framework of the discourse within which more particular claims of knowledge and expressions of doubt make sense. Wittgenstein calls them 'grammatical' propositions – thereby according them a constitutive, sense-fixing or practice-fixing role – and described them figuratively as the 'scaffolding' of our ordinary thought and talk; or, varying his metaphor, as the bed and banks of the river of our discourse.

VIII

Whatever one makes of the quasi-Foundationalism of Wittgenstein's approach in 'On Certainty', its similarity to its forerunners in Hume and Kant is suggestive, and prompts one to remember that part of Kant's aim in arguing that our cognitive structures play an essential constitutive role in shaping how the world appears to us, is precisely to address the 'scandal of philosophy', which as he saw it was its inability hitherto to reply adequately to sceptical challenges.

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