Philosophers have gone on wrestling with scepticism in contemporary philosophy, and have come up with some ingenious arguments to keep the problem at bay, while striving not to succumb to dogmatism in the process. For Ludwig Wittgenstein, our methods of enquiring into the truth of our knowledge and belief have a background that we can depend upon with what amounts to certainty. There is a ‘scaffolding’ that ‘stands fast’ for us in such cases, making enquiry possible in the first instance:

All testing, all confirmation and disconfirmation of a hypothesis takes place already within a system. And this system is not a more or less arbitrary and doubtful point of departure for all our arguments: no, it belongs to the essence of what we call an argument. The system is not so much the point of departure, as the element in which arguments are made.

There are limits to scepticism, in other words, which in Wittgenstein’s view ought to restrict some of the method’s wilder excesses. These are sentiments which will go resolutely unheeded by the super-sceptics, however, whose reflex will be to probe away at what constitutes the ‘scaffolding’ and to be unsatisfied by any insistence that they can, or should, go no further than that.

It seems to be a characteristic of contemporary mainstream philosophy (the analytical tradition) to try to neutralise scepticism as a philosophical position, calling into question its assumptions and methodologies. As one notable defender of the sceptical outlook, Barry Stroud, has put it, scepticism in philosophy has been found uninteresting, perhaps even a waste of time, in recent years. The attempt to meet, or even to understand, the sceptical challenge to our knowledge of the world is regarded in some circles as an idle academic exercise, a wilful refusal to abandon outmoded forms of thinking in this new post-Cartesian age.

Stroud, as we shall see below, strongly disagrees with this negative assessment. Yet the anti-sceptical impulse is nevertheless commendable enough in its way, being concerned to prevent philosophy from collapsing into arguments about the grounds for argument, in which case the subject is not addressing all the other problems in the world around us – problems of ethics and politics, for example. Finding flaws in the sceptical position is also a way of arresting a slide into relativism – something that any socially conscious mainstream philosopher is generally keen to avoid, with its implications of an anarchic ‘anything goes’ approach to ethics and politics (a charge frequently made against the super-sceptics).

Hyperbolic doubt in particular comes in for very close scrutiny, with its basic premises being strongly challenged. Such doubt can go the extent of questioning the very existence of the external world, and here contemporary anti-sceptics have been particularly critical, offering several counter-arguments to what they consider to be an untenable, and certainly socially unhelpful, position. One way of posing the problem is to suggest that rather than a body in the world you might just be a ‘brain in a vat’, connected up to a very powerful computer by some evil scientist such that you are given the impression of bodily existence. Hilary Putnam, however, argues that a brain in a vat could not have such a thought itself, and that ‘the supposition that we are actually brains in a vat . . . is, in a certain way, self-refuting’. Brains in vats simply could not have the same experiences that human beings with bodies do: ‘one cannot refer to certain kinds of things, e.g. trees, if one has no causal interaction with them, or with things in terms of which they can be described’.

Scepticism comes to seem a wilfully wrong-headed way of looking at things to Putnam, who dismisses the relativism that can come in its wake on the grounds that it could not be consistently held: ‘To say this is not to deny that we can rationally and correctly think that some of our beliefs are irrational. It is to say that there are limits to how far this insistence that we are all intellectually damned can go without becoming unintelligible.’ Reasonably enough, it is the dogmatic tendency within scepticism that Putnam is most concerned to undermine: the tendency to universalise from particular instances. This proves to be something of a recurrent theme amongst contemporary anti-sceptics.

Robert Nozick takes particular issue with scepticism in his book Philosophical Explanations, which, as the title indicates, wants to move the emphasis of philosophical enquiry away from proof to explanation. This immediately distances him from philosophical sceptics, who invariably want to question and raise doubts as to how certain things are possible – how do we know there is an external world or other minds, that we are not a brain in a vat, etc.? – rather than seek an explanation for them. Sceptics traditionally want to leave us with problems, not answers. Instead of setting out to refute scepticism, Nozick looks for ways to bypass it: ‘to formulate hypotheses about knowledge and our connection to facts that show how knowledge can exist even given the skeptic’s possibilities’. The intent is to be positive rather than negative, with Nozick arguing that a philosophy based on explanation is ‘morally better’ than its rivals (Nagarjuna would disagree); even though he concedes the value of scepticism in prompting non-sceptics to re-evaluate their belief system on a regular basis. The message is that in small doses scepticism is good for you.

Nozick postulates a clear link between knowledge and belief. We believe what we know to be true, and we do not believe what we know to be false: ‘I am writing on a page with a pen. It is true that I am, I believe that I am, if I weren’t I wouldn’t believe that I was, and if I were, I would believe it.’.  Our beliefs ‘track facts’, as Nozick describes it, and scepticism in no way affects this practice or how we reach judgements about whether particular beliefs are justified or not.70 If not entirely refuted, scepticism is, in Nozick’s opinion, at least a much reduced problem by the end of his analysis of its claims: a useful corrective to philosophical complacency, if not much more than that perhaps.

Despite such attempts to neutralise the force of scepticism, some philosophers still regard it as a source of intractable problems for the philosophical enterprise. Stroud, for example, argues that it is a deeply significant element of philosophical thought, claiming that ‘[b]y examining philosophical scepticism about the external world I hope to bring into question our very understanding of what a philosophical theory of knowledge is supposed to be’. Far from being a barrier to our understanding of the world, scepticism holds the key to it for this thinker and he wants to see it play a larger role in mainstream, analytical philosophy than it is currently doing (Stroud does not engage here with the burgeoning continental tradition of super-scepticism). Stroud’s argument is that scepticism leads us back to the problem itself, and that we need to re-examine how and why the problem arises. While it is perfectly reasonable to think that our senses could deceive us, as patently sometimes they do, it is altogether more questionable to generalise from this observation to say that they are therefore totally unreliable as a source of knowledge about the external world:

If my own sensory experiences do not make it possible for me to know things about the world around me they do not make it possible for me to know even whether there are any other sensory experiences or any other perceiving beings at all.

Stroud proceeds to look closely at our methods of assessing claims to knowledge, and puts forward a series of what he calls  ‘platitudes’, observations that all of us would accept about the world and our understanding of it and that work against the more extreme, even dogmatic, forms of scepticism vying for our attention: platitudes such as that we do not think it unreasonable to act in some situations even if we do not have absolute certainty about what the outcome will be, or that sometimes we find it reasonable to subject our beliefs to challenge and other times we do not (and that not a lot necessarily hangs on each particular decision either way). The platitudes Stroud outlines derive initially from sceptical enquiry, meaning that, for this philosopher, scepticism becomes the source of our proof of the existence of the external world. Whereas most mainstream philosophers seek to undermine scepticism in the process of reaching this conclusion (seeing the scepticism itself as the problem), for Stroud it reinforces scepticism as a mode of thinking.

As long as commonly accepted methods of proof exist, then the independence of the world lies beyond reasonable doubt. Scepticism invites us to keep scrutinising our knowledge, and deciding whether it is justified or not: ‘The force we feel in the sceptical argument when we first encounter it is itself evidence that the conception of knowledge employed in the argument is the very conception we have been operating with all along.’ The very fact of being able to frame sceptical questions indicates that we do have a basis from which to test our knowledge claims, rather like the notion of scaffolding in Wittgenstein: we can rely, Stroud maintains, on ‘the familiar assessments of knowledge we know how to make in everyday life’. We need to have a sense of the independent existence of the world, in other words, in order to cast it into doubt.

The benefit of philosophical scepticism for Stroud is that it forces us to examine what lies behind all those ‘familiar assessments’, and this encourages a high degree of rigour in our reasoning. Where scepticism becomes problematical is when there is overgeneralisation from particular cases, as Putnam also notes. It is only when this occurs that the more extreme claims can be made about the lack of proof for the existence of the external world, and it is such claims that have brought scepticism into disrepute – both inside and outside the realm of philosophy.

‘What use are such claims?’, is a common objection from professional and lay-person alike. Stroud does think that some generalisations can be made from particular experience, however, arguing that, ‘[i]t could not be shown that when the philosopher generalizes from his particular assessment to a conclusion about human knowledge in general he inevitably denies or withdraws one of the presuppositions that make it possible for his challenge to work as it does in the particular case’. It is that possibility that prevents mainstream philosophy from dismissing scepticism out of hand; the latter, carefully handled, continues to pose awkward questions for the traditional philosophical models of how we come to have knowledge of the world. To that extent we can describe it as philanthropic in Sextus’ sense of the term.

Stroud manages to show how scepticism sometimes overstates the case, while never quite altogether losing credibility as a philosophical position: it is integral to philosophical thinking in this reading. Things are left interestingly open at the end of his book The Significance of Philosophical Scepticism, but scepticism plainly has not been defeated by its adversaries, and Stroud has made us very aware of the positive role it can play within philosophical discourse – and potentially in everyday life. We need to keep Stroud’s stricture about overgeneralisation in mind in our own sceptical project, ensuring that scepticism remains an open-minded approach rather than an aid to dogmatism, but recognising, too, that it holds out the possibility of generalisation in certain situations (enough for the sceptic to go to work on). A somewhat similar approach to scepticism can be found in the work of Christopher Hookaway, who recognises the force of sceptical arguments, while not wanting to accept their more pessimistic conclusions: ‘it is argued that sceptical arguments question our ability to participate in the activities involved in enquiry without feeling that our ability to take responsibility for our actions is compromised’. Even though Hookaway suggests there are several ways to overcome scepticism, he still sees it as a valuable part of philosophical enquiry, as long as we are careful to ameliorate some of its more extreme claims and projections:

a position which despairs of answering sceptical challenges but describes the ways in which we evaluate beliefs and assertions, suggesting that we can recognise their value without being able to defend them against sceptical onslaught, may be placed in a different perspective when it is seen as the epistemic counterpart of soft determinism: soft scepticism, as we may call it.

(‘Soft determinism’, by the way, is the position that we can still consider ourselves to be free agents, even though we have to accept the restrictions placed on us by the laws of physics: ‘Freedom and responsibility are compatible with physical determinism.’) Soft scepticism invites us to keep testing our ‘cognitive goals’, while not denying our claim to be rational and autonomous agents in doing so. In effect, this is scepticism without the traditional drawbacks from the perspective of the mainstream philosopher.

One senses that both Stroud and Hookaway would be happier were scepticism never to arise, but feel at least bound to accept its presence within the philosophical enterprise. The virtue of scepticism in making us realise the contingent nature of much of our knowledge and belief is fully acknowledged by both these commentators, however, and that is a first step in the campaign to combat dogmatism.

Nowhere has scepticism thrived more in contemporary philosophy, however, than in later twentieth-century France. There, poststructuralism and postmodernism have generated a large and enthusiastic school of super-sceptics who have rejected all attempts at neutralisation of the sceptical impulse – and not from the measured position of someone like Stroud or Hookaway, both of whom want to keep dialogue with scepticism firmly within the philosophical mainstream.