Scepticism

Neil Gascoigne

• Publisher: Routledge
• Year: 2014
• ISBN:
  9781317489702
• Edition: 1
• Topic: Filosofia
• Subtopic: Storia e teoria della filosofia

The history of scepticism is assumed by many to be the history of failed responses to a problem first raised by Descartes. While the thought of the ancient sceptics is acknowledged, their principle concern with how to live a good life is regarded as bearing little, if any, relation to the work of contemporary epistemologists. In "Scepticism" Neil Gascoigne engages with the work of canonical philosophers from Descartes, Hume and Kant through to Moore, Austin, and Wittgenstein to show how themes that first emerged in the Hellenistic period are inextricably bound up with the historical development of scepticism. Foremost amongst these is the view that scepticism relates not to the possibility of empirical knowledge but to the possibility of epistemological theory. This challenge to epistemology itself is explored and two contemporary trends are considered: the turn against foundationalist epistemology and towards more naturalistic conceptions of inquiry, and the resistance to this on the part of non-naturalistically inclined philosophers. In contextualizing the debate in this way Gascoigne equips students with a better appreciation of the methodological importance of sceptical reasoning, an analytic understanding of the structure of sceptical arguments, and an awareness of the significance of scepticism to the nature of philosophical inquiry.

1 Scepticism and knowledge

Introduction

The aim of this chapter is to provide a preliminary introduction to the problem of scepticism as a contemporary epistemologist would see it; namely, as a problem that emerges when one adopts the theoretical attitude towards knowledge claims. In pursuit of this aim, the chapter has three main objectives: first, to enquire into what it is that the sceptic doubts and therefore discover to what aspect of our human self-understanding that doubt poses a threat; secondly, to examine two ways in which the sceptic goes about generating her doubt, the so-called ‘argument from ignorance’ and the ‘Agrippan argument’; and finally, to provide a context from within which the threat of sceptical doubt and the ways in which it is generated can be seen to relate to the concerns of the contemporary epistemologist. In the fulfilment of these objectives I intend to motivate my claim that to understand sceptical doubt more fully we need to know something of its historical development.

The task of epistemology

The central task of epistemology as many philosophers see it is summed up by the American philosopher Barry Stroud:

We aspire in philosophy to see ourselves as knowing all or most of the things we think we know and to understand how all that knowledge is possible. We want an explanation, not just of this or that item or piece of knowledge, but of knowledge, or knowledge of a certain kind, in general.

(1994: 296)

We all claim to know lots of things and presumably aspire to know a lot more. It is important both to our self-understanding and to our understanding of others that knowledge has a value that sets it over and above mere opinion. Whenever we claim to know something or encounter someone making such a claim, we recognize that something is at stake: the claimant has represented himself or herself as satisfying whatever conditions make something a case of knowing. One of the responsibilities that goes along with that representation is to be able to offer reasons why this is a case of knowing and not just one of opinion.

There is nothing mysterious about this; indeed, it is the most common of phenomena. I know that the Sears Tower is in Chicago. If asked how I know this, I might mention that I initially saw a picture of it in a travel guide and then go on to say that I have been to Chicago and seen it for myself. Perception, memory and testimony (I tend to trust the people who write travel guides) all contribute to an explanation of this particular item of knowledge, and there doesn’t seem anything unsatisfactory about the reasons I give – certainly nothing that we would look to philosophy to remedy. Contrasting with this, Stroud identifies a much more demanding aspiration. What we want, he suggests, is the assurance that our concept of knowledge is itself legitimate; that creatures like us are entitled to think of ourselves as knowers, and that we aren’t just deluding ourselves when we claim to know all the things we think we do. This assurance is to be gained by explaining how knowledge (or knowledge of a certain kind) is possible.

On Stroud’s account, then, the epistemological task is to demonstrate that our concept of knowledge is legitimate by explaining how knowledge is possible. Note that as these things are usually viewed this is a normative problem, not a descriptive one. It is not going to be answered by giving us facts about how we do or do not use the concept of knowledge; neither is it going to be answered by giving us a scientific account of, say, the nature of perception (since such an account would presuppose that scientific knowledge is possible). Rather, an answer must be in the form of an account that gives us reasons to believe we have a right to use the concept. Moreover, since the account is to be general, these reasons will not be tied to specific examples of knowing like those given in defence of my claim to know that the Sears Tower is in Chicago (perception etc.). The reasons that constitute any explanation of how knowledge or knowledge of a certain kind is possible are going to be relevant to all such claims to know, irrespective of whether they are about towers, trees or tentacles.

In very general terms we might distinguish three responses to what Stroud identifies as the task of philosophy, what I’ll call the heroic, the rejectionist and the sceptical. The heroic response is Stroud’s own, and it provides a preliminary answer to the question ‘what does the sceptic doubt?’ What the sceptic doubts is that knowledge (or knowledge of a certain sort) is possible. On the heroic understanding of epistemology, scepticism is at the heart of enquiry because it is only by responding to the sceptic’s doubts that it can be demonstrated that knowledge is indeed possible. The rejectionist response is to deny that showing how knowledge is possible is central to epistemological enquiry, and therefore to deny the centrality of sceptical doubt.¹ To take a well-known example, the proponents of what is called ‘naturalized epistemology’ proceed on the assumption that knowledge claims are not irreducibly normative, and that knowledge does not in general stand in need of philosophical legitimation. Epistemology is therefore not a normative enquiry but an extension of the methods of the natural sciences.

Despite divergent views on the importance of scepticism, the heroic and rejectionist responses are both part of the modern epistemological tradition. Indeed, as we’ll see below, rejectionism can be viewed as a reaction to the perceived failure of epistemological heroism. The sceptical response derives from a far older tradition, and exhibits a different understanding of what scepticism is. It does not concern the direct question of whether knowledge is possible (although it is clearly related) so much as the question of whether it is possible to offer an account that shows us that knowledge is possible. Viewed from the perspective of the heroic response, the sceptic is a philosophical opponent who calls into question the possibility of knowledge by providing reasons for doubt. This sets the task for the heroic epistemologist: to give us reasons for thinking that these doubts are unwarranted, thereby entitling us to see ourselves as knowing what we think we know. From the perspective of the sceptical response, however, philosophical reasoning is the target – the possibility of philosophical knowledge itself is called into question. In so far as both heroic and rejectionist epistemologists aspire to the possession of philosophical knowledge (pk), then, their theoretical activities attract the attention of the sceptic. To avoid confusion, we’ll call this variety of scepticism pk-scepticism and reserve the name scepticism for what is of interest in traditional epistemology. We’ll turn to the relationship between the heroic, rejectionist and sceptical responses at the end of this chapter. For the time being we’ll restrict our attention to the variety of scepticism that presents a challenge to the heroic task by questioning the possibility of what we commonsensically understand as knowledge.

The argument from ignorance

How then does the sceptic give us reasons for doubt about the possibility of knowledge? The answer in part depends on what kind of knowledge we’re talking about. For most contemporary philosophers the kind of knowledge we’d particularly like to see ourselves as possessing is perceptual knowledge, what is usually referred to as knowledge of the external world. Right now I’m sitting in a library typing – I can see my new computer in front of me, feel the heat from the keyboard, smell the upholstery of the chair I’m in, hear the whirring of the air-conditioning, taste the chocolate in my mouth. I want to say that I know that I’m sitting wide awake in the library (or rather, I say that I am and that is taken as a claim to know). Here the sceptic casts doubt on the possibility of such knowledge by aiming to undermine my confidence in the cognitive status of my perceptual experiences. She points out that I might be dreaming; or perhaps even a disembodied brain, wired up to a supercomputer and floating around in a vat of nutrients. Both of these sceptical possibilities are seemingly consistent with my having exactly the same perceptual experiences as I’m having now, but in neither case would those experiences be reliable guides to what’s really going on in the world.

By invoking possibilities like these, the sceptic presents a challenge to the epistemologist who wants to show how knowledge of the external world is possible. How can it be, if I rely entirely on experience and yet what I experience is consistent with not knowing what I ordinarily take myself to know? And what applies to me, applies equally to you! This particular way of generating doubt can be usefully generalized in the form of an argument. Letting S stand for any subject, q for any empirical proposition (like ‘I’m awake in the library’ or ‘I’ve got two hands’) and sp for any of the sceptical possibilities mentioned (like ‘S is an envatted brain’), we have the following:

• S doesn’t know that not-sp
• If S doesn’t know that not-sp, then S doesn’t know that q

Therefore

• S doesn’t know that q

This is an example of what’s called an ‘argument from ignorance’. It’s often associated with the sceptical arguments Descartes put forward in his Meditations, and many philosophers take it to be a definitive statement of the sceptic’s challenge to our perceptual knowledge claims. If we can’t come up with a philosophical response to the argument from ignorance, the thought goes, the sceptic has exposed the fact that despite our intuitions to the contrary we cannot show how knowledge of the external world is possible.²

No-stipulations principle

A great deal of philosophical effort has been expended in the attempt to show that the argument from ignorance is unsound or otherwise uncompelling, and we will consider a number of specific attempts in subsequent chapters. For present purposes it’s important to remember that the epistemological task is to show how knowledge is possible. As such, efforts to reject the argument from ignorance frequently focus on offering an analysis of knowledge that links its possibility to an account of where the argument from ignorance goes wrong. To take a simple example, let’s imagine that knowing just requires believing that something is possible; that is to say,

• (A) S knows that q iff (if and only if) S believes it is possible that q

On this account, the argument from ignorance is immediately shown to be unsound, as the first premise is false – I do know that I’m not for example an envatted brain because I believe it’s possible that I’m not. On this analysis the argument from ignorance does not therefore present an obstacle to the possibility of knowledge. The problem with this is that no one thinks that (A) is satisfactory – it fails to capture our intuitive sense of what it is to know something. The moral of this is the ‘no-stipulations principle’: the epistemologist can’t just invent an account of what knowledge is in order to refute the sceptic and show that knowledge is possible. Now consider the following:

• (B) S knows that q iff everyone everywhere believes that q, but only on Wednesdays if it’s raining

What this suggests is that the no-stipulations principle also cuts the other way: an arbitrary account of knowledge that simply made it unobtainable would cause us to lose no sleep over our cognitive shortcomings. ‘If that’s knowledge,’ we might exclaim, ‘who gives two hoots that we don’t know anything?’ In short, at one extreme stipulation leaves sceptical doubt unintelligible at the cost of making knowledge worthless (A); at the other extreme it makes scepticism unthreatening at the cost of making knowledge impossible (B).

We can draw two related conclusions from this. First, since no one stipulation as to what constitutes knowledge has any greater claim on us than any other, another guide is clearly needed. The knowledge whose possibility the sceptic doubts must be something of which we have an intuitive (perhaps pre-theoretical) grasp. It must be something connected to the way we (at least implicitly) use the concept in everyday life and which captures its importance to our understanding of ourselves as cogn...