MWP 1.1.b: The Failure of Philosophical Arguments against Scepticism

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Philosophical arguments against scepticism have come in broadly five types, as far as I can identify:

  1. The assertion of self-evident truths (e.g. Descartes)
  2. Arguments that scepticism is practically unsustainable, and thus that dogmatism is unavoidable (e.g. Hume)
  3. Arguments that scepticism involves practical inconsistencies (e.g. Burnyeat, Nussbaum)
  4. Arguments that scepticism is unjustified because it only offers negative grounds of judgement (e.g. Moore and other positivists)
  5. Arguments that scepticism makes invalid semantic assumptions (e.g. Wittgenstein)

I shall argue here that each of these lines of criticism itself involves assumptions that we do not necessarily need to make in approaching the subject. The case for not making these assumptions is not merely sceptical, but also pragmatic.

1.  If self-evident truths exist then this would obviously undermine scepticism, as there would be a foundational certainty from which other certainties might then be deduced. Descartes’ cogito, in which the certainty of the thinker’s existence is deduced from the experience of a thought, is the classic example of a self-evident truth[1]. In 1.g I will provide a more detailed response to the claim that a priori propositions such as mathematics or the laws of logic provide self-evident truths.

But for the moment let us accept for the sake of argument that there might be self-evident truths such as that I, a thinker, exist at this instant. Since it is not empirical, this claim avoids the first six sceptical arguments listed in the previous chapter, and it avoids the seventh, the infinite regress, if its foundational claims are justified. However, this claim and any other foundational claim are still subject to the last two sceptical arguments that point out the relativity and vagueness of linguistic categories. “I, a thinker, exist at this moment” is relative to each thinker because it can only be interpreted according to the linguistic understanding of each individual thinker. If you tell me that you exist at this moment, to me that obviously means that you exist at this moment, which means something rather different from me existing at this moment. Unless this statement has an absolute unchanging meaning for all who may comprehend it – which it clearly does not – it can hardly have an absolute unchanging justification. The same point would apply to mathematical or logical claims (see 1.f), if considered in accordance with the account of meaning that will be presented fully in volume 3.

The ambiguity of statements supposedly offering self-evident truths creates contradictions in the very claims involved. “I, a thinker, exist at this moment” for example, either means that a thinker exists over a short period of time, or at a genuine instant of time with no duration. If the former, the thinker can have thoughts (which always take up a certain amount of time), but by the time the thinker gets to the end of her thoughts, she may be different from when she started them and thus no longer “exist” in the absolute, unchanging sense required. On the other hand, within an instant without any duration, no thoughts can take place and thus it seems that a thinker cannot exist.

All these kinds of arguments (the sport of philosophers, but very tiresome after a while) are merely different ways of showing that we, being non-absolute creatures, cannot handle absolutes without constantly contradicting ourselves. Our physical experience and our language shrug off absolutes as water shrugs off oil. Philosophers should know better by now than to go in for any kind of absolute, and self-evident truths are unavoidably absolute in their claims.

2. Hume’s argument about scepticism, on the other hand, attempts to adopt a no-nonsense practical approach to it. After admitting that we cannot refute scepticism on its own terms, Hume seems to be saying that there is no way that we can, in practice, accept those terms. It is ‘nature’, he says, that drives us to belief, rather than reason, because when we engage with objects in the world around us we do so on the basis of a practical assumption of their existence and form. Scepticism is all very well in the abstraction of a study, but there is no way we can keep it up in ordinary life:

‘I dine, I play a game of backgammon, I converse, and am merry with my friends; and when after three or four hours’ amusement, I would return to these speculations, they appear so cold, and strained, and ridiculous, that I cannot find in my heart to enter into them any farther.’[2]

Hume makes an unjustified assumption about the implications of scepticism here: indeed, he gets the whole matter the wrong way round. Scepticism casts doubt on any claims to certainty, but this does not imply that to take it seriously means that we must be constantly straining to disbelieve what we encounter in everyday experience. On the contrary, our everyday experience involves uncertainty, and scepticism, far from relying on ‘cold’ and ‘strained’ calculations, uses this everyday experience as its point of departure. It is claims of certainty, and the attempt to justify them, that go far beyond everyday experience and become cold and strained.

This point is closely related to another that I will consider more closely in 1.e: namely the distinction between denial of claims and denial of certainty about them. If we were to assert the opposite of everything we take for granted in everyday life, e.g. that there is not a table in front of me, that the world does not exist etc, then this would indeed be a cold and strained exercise. However, there is no reason why we should have to interpret sceptical arguments in this way. Scepticism denies certainty, and thus leaves us in a position lacking certainty, rather than asserting the opposite of our accepted beliefs. To assert the opposite would be at least as uncertain an enterprise. Hume, however, (along with many of his successors) seems to confuse these two positions.

3. Burnyeat and Nussbaum, on the other hand, respectively accuse scepticism of other kinds of practical inconsistency. Burnyeat claims that it’s impossible to maintain the degree of detachment from one’s views that scepticism demands[3]. Nussbaum argues that the classical sceptics are dogmatic about the value of ataraxia, which in classical Pyrrhonian scepticism is the relaxed state of detachment from opposing certainties[4]. Both these objections could be seen as versions of what is sometimes called ‘the paradox of scepticism’: namely, that sceptics are certain about uncertainty. This supposed paradox can be presented either as a direct contradiction or at least as a practical inconsistency.

Both of these thinkers are commentators on the classical sceptics and make these remarks in the context of discussing classical Pyrrhonism. I am purposely avoiding too much discussion of the scholarly issues about historical schools of philosophy here, but am attempting only to isolate what we do or do not need to think about sceptical arguments based only on the implications of the arguments themselves[5]. Burnyeat’s and Nussbaum’s arguments may or may not be true of classical Pyrrhonism, but my argument is that their criticisms distract us from the useful insights offered by this line of sceptical argument in the modern context.

Both of these objections fail to take sufficiently into account the distinction between the denial of claims and the denial of certainty about claims. If we assert the opposite of a given claim, we raise the same issues of certainty about it as with the original claim. If we merely deny the certainty surrounding a claim, however, we modify the way in which that claim may be held rather than setting up a new claim. If we understand the modification of the way we hold a claim in psychological terms, rather than merely in terms of opposing propositions, this becomes clearer. I will explore this point in more detail in 1.c. A claim not held with certainty is held in a more provisional and a more relaxed fashion, which may also affect our subsequent judgements about how to assess it. Contrary to Nussbaum’s assumptions, the value of such a provisional state is not one that we have to accept absolutely and all at once, but is a matter of incremental recognition (a point that interlocks with various other arguments about value to be found throughout this book).

Burnyeat overestimates the degree of detachment required to take scepticism seriously, because he shares the confusion between denial and provisionality with many modern commentators. We do not need the amount of detachment that would be required to seriously adopt a position of denying all our beliefs in order to merely hold them provisionally. Nor does it require a certain fixed amount of detachment in order even to hold them provisionally. If we think about provisionality in an incremental rather than an absolute way (see 1.e) then we can think of the process of giving up attachment to certainty as a gradual and dynamic one. This process then becomes practically achievable in a way that a sudden demand for massive detachment would not. 

4. Another, positivist type of response to scepticism is to assert that only positive justifications for belief are acceptable, and that negative doubts about a claim not accompanied by definite evidence against the claim are inadmissible[6]. The logical positivists and their allies in the early twentieth century saw this as a way of protecting evidence-based scientific investigation against the encroachments of metaphysics. Those who deny commonly accepted empirical beliefs, after all, often do so only on the basis of speculation.

Much as I sympathise with the logical positivist attempt to distinguish metaphysics from claims that can be justified through experience, the positivist route does not succeed in doing this. Positivism prevents us from taking negative doubts seriously, and simultaneously makes its own metaphysical assumptions unassailable. We need negative doubts in order to be able to consider conventionally accepted beliefs from an adequately critical perspective. The positivist dismissal of negative doubt leaves us dependent upon conventional beliefs and unable to break out of the set of assumptions that are currently accepted in our context. Logical positivism, and its successors in analytic philosophy, remain dependent on analysis of conventional positions or commonly shared intuitions, and unable to reach a justified critical standpoint beyond those conventional positions.

Like many of the previous criticisms, too, positivism confuses denial with the mere acceptance of uncertainty. Negative doubts require us to accept the possibility of currently accepted beliefs being wrong, not to accept the alternative claim that they are definitely wrong. Speculative metaphysics puts forward new claims that are beyond experience – so sceptical argument is a crucial tool that should be used for combating metaphysics, not discarded at the very point when it would be most useful.

A more specific version of this positivist argument is that used by both Moore[7] and Wittgenstein[8] in slightly differing ways to assert the existence of their hands as a basic certainty. Their reason for dismissing scepticism about something as certain as the existence of one of their hands was not just that mere negative doubts were inadmissible, but that any evidence that could be used to support the assertion that their hands existed would be less certain than the existence of their hands. For positivists, then, some kinds of claim have to be taken as certain and basic to all other discussions. Without those basic assumptions, it is argued, the discussion could not take place.

This argument, even if it is valid in other ways (and there are many other ways that its assumptions can be disputed), can only be directed against the error argument, and other sceptical arguments that raise one specific doubt whilst taking a wider context for granted. It does not apply to the dream argument, or the infinite regression argument, or the linguistic arguments. The dream argument does not require us to take one kind of fact for granted in order to cast doubt on others, only that there be some unspecified factual basis to use as a ground of contrast with a current uncertainty. Similarly, the infinite regression argument can be used against any claim of certainty whatsoever, regardless of its relationship to other claims, and the relativity and ambiguity of the linguistic composition of these claims remains regardless of its relationship to other claims.

5. Finally, Wittgenstein’s objections to sceptical argument were also based on the alleged linguistic privacy of sceptical argument, and his objections to linguistic privacy in the so-called private language argument[9]. However, he was mistaken on both counts. Not only is scepticism not necessarily based on linguistic privacy (assuming that we can even make sense of the idea of linguistic privacy), but there is no reason to assume that language developed in linguistic privacy is meaningless.

The Cartesian version of scepticism, in which I can entertain the possibility of being the only real thing in the universe, does not depend on solipsistic assertions but only on the possibility of solipsism (the same confusion we have already noted). However, all the other types of sceptical argument mentioned above, including the modes of Pyrrhonism and the linguistic arguments, could just as well be applied to a publicly shared context as to a ‘private’ one. I might be wrong about my perceptions, but we might also be wrong about our collective perceptions, for very similar reasons. The publicity or otherwise of the language makes no substantial difference to these kinds of arguments.

The concept of linguistic privacy, completely and absolutely distinguished from linguistic publicity, seems dubious in the first place to me. We use language to communicate with others, but we also use it to communicate with ourselves over time (as in a private diary) and perhaps even to articulate without communicating (as when we talk to ourselves to clarify our thoughts). Wittgenstein simply assumes, without further justification, that the only acceptable function of language is communication. He then asserts that when using purely private language (i.e. a symbol whose significance is known only to me) in a private diary, when using it later I would have no clear criterion of meaning. However, I would have a relative criterion of meaning based on my memory of previous experience which the symbol represented. A falsely absolute distinction is made if it is assumed that the private criterion is relative whilst a public one is absolute, for there is no guarantee that a publicly used piece of language, even within a particular language game (i.e. social context where that language is shared) is not equally ambiguous. Like the other attacks on scepticism, then, Wittgenstein’s do not apply to all the arguments, and also confuse lack of certainty with definite denial. Like the other attacks, it is based on a confusion about the purpose and implications of scepticism, as should become clearer as we go on. A complete reversal of the assumptions in all these attacks on scepticism is required. Scepticism is not a dragon to be slain, but rather a knight in shining armour. It is certainty that is the dragon.


[1] Descartes (1641/1968)

[2] Hume (1978) p.269

[3] Burnyeat (1980)

[4] Nussbaum (1994)

[5] A similar argument to mine, but grounded more in the historical context, is found in Kuzminski (2008) ch.1

[6] E.g. in Ayer (1946)

[7] Moore (1962)

[8] Wittgenstein (1969)

[9] Wittgenstein (1969). See note 5 to 1.1.a.

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