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Scepticism in the Twentieth Century:

Moore and Wittgenstein

Matthew Carmody and Paul Sheehy

1. Introduction

Ask a friend who has never studied philosophy what he or she thinks the subject is all about. There is a very good chance that prominent in their thoughts is the idea philosophers spend rather a lot of time worrying whether one can know that ordinary objects are really there in front of us. That is to worry whether we can know that things are as they seem. Now your friend may think the answer is obvious. Of course we can know that things are (pretty much) as they seem. Or, of course we cannot know - haven't you seen the film The Matrix? But, why should this worry us?

At the heart of caricature is truth. The comic exaggeration or ludicrous misrepresentation of someone's features bites because in the distortion there remains that which is saliently and immediately recognisable and characteristic. Philosophers and philosophy sometimes suffer the fate of being caricatured - preferable it should be noted to the more common and damming state of being ignored. An enduring image of the philosopher-and of the central task of philosophy-is someone asking the question: "But, can we know that?" Whatever evidence or reasons offered in favour of the belief in question the philosopher can raise the possibility of doubt, and point to the sceptical worry. If I can doubt that such and such is the case, then I should refrain from saying I know that it is the case. The philosopher, along with the subject to which he has devoted his lonely, eccentric and no doubt scruffily-attired life, is revealed to be concerned with an endless question. For in asking whether we can (really) know that such and such is the case the philosopher initiates a hunt for conclusive evidence which is not to be had and, in failing to recognise that, the philosopher is condemned to a practically useless life. What can asking an unanswerable question achieve? Why demand that absolutely conclusive evidence be required to entitle us to say that we can know that such and such is the case? It can have no practical impact on one's life and that life is surely too short to care or worry about establishing that I am entitled to say with certainty that I know.

The truth in the caricature is the central role played by the question of whether we can say that we know that something is the case or not. Indeed, the question generalises as the caricature suggests. It becomes the very big question of whether we can know anything. The misrepresentation is located in the sense of pointlessness in pursuing this question. Our relationship to the world and our understanding of ourselves are framed in terms which inescapably refer to what is knowable; and it is significant that we elevate certain beliefs to the status of knowledge for knowledge is endowed with an authority beyond mere belief. In our formal studies of, say, philosophy, mathematics, sociology and literature we presuppose that there are some things which we know. Likewise, in our everyday lives we only make sense of the world given a host of matters we take for granted that one knows along with others. The possibility that one may not be entitled to make such knowledge claims - that much or all of what I took myself to know I am not entitled to regard as knowledge - requires a reorienting of my basic understanding of myself and the world.

2. Philosophical Doubt and the Gap

There is a distinctively philosophical kind of doubt that involves those things which it is logically possible to doubt - that is, those claims which could be false. Take any proposition one might ordinarily claim to know. For our purposes p is the proposition, "Paul is wearing a black shirt". Imagine that S is one of Paul's students and that it is indeed the case that p is true. S has excellent grounds justifying her belief. The evidence includes the fact S is having a visual and auditory experience of Paul explaining scepticism, that Paul has always worn a black shirt, S's senses are in good working order and so on. Call the set or conjunction of those grounds or evidence, e. On the basis of e it seems that:

S knows that p

The sceptical challenge is that it is possible that S possesses the best possible evidence or reasons supporting her belief that p yet for that belief to be false. There is no contradiction involved in the conjunction of statements (e) representing our best grounds for believing that p and the falsity of p. It is not contradictory to hold that (e and not-p). It is possible that Paul is sitting in his underwear at home while a hologram is being projected in front of the class or that S is dreaming or that S has been drugged or is the subject of systematic deception by being the victim of an all-powerful demon, is in reality a brain in a vat or is part of the Matrix or... The point is not whether these are likely scenarios, but that they cannot be ruled out. That inability to rule out the falsity of p opens a gap between the evidence for one's knowledge claims and the truth of the claims themselves.

Philosophical doubt is distinct from what we might call ordinary or everyday doubts which arise because of, for example: lack of evidence; the occasional lack of reliability in certain faculties (c.f. our efforts to reason cogently whilst under the influence of drink or drugs); distrust in one's capacity to reason correctly (e.g. to employ mathematical or logical rules and procedures); or because of a lack of expertise or confidence on our part. The reasonable doubt of the judicial process is a species of ordinary doubt - imagine how difficult convictions would be to secure if the prosecution had to overcome the hurdle of philosophical doubt.

3. Why Bother?

The philosopher Sextus Empiricus distinguished two varieties of scepticism that had been pursued by his predecessors in antiquity.[1] The word "scepticism" comes from the Greek verb skeptesthai mean to "to look at (closely)" and hence "to enquire". (You can find the original meaning of the verb today in the English words "microscope" and "telescope".) Pyrrhonian scepticism is named after the philosopher Pyrrho of Elis (c.365-275 BCE). Pyrrho argued that enquiry can never enable us to learn how things are.[2] Sextus put the point by saying that there are always equal arguments for and against a conclusion. We should therefore suspend judgment on the conclusion rather than doubt whether it is true.[3] Since we cannot learn how things are, there is no point in being concerned, intellectually or otherwise and hence we reach a state in which freedom from worry ("ataraxia"). Scepticism leads to the end of philosophical enquiry because it is fruitless.

It follows from the Pyrrhonian view that one must suspend judgment on whether knowledge is possible. The second variety, Academic Scepticism, argued that knowledge was impossible. It is this form of scepticism that is familiar to us today. The significance of sceptical considerations grew as the scientific and intellectual developments of the late sixteenth and seventeenth centuries called into question the orthodoxy of the predominant religious worldview. The need to distinguish genuine knowledge, to establish a conceptual basis for scientific enquiry gave urgency to questions concerning knowledge. In the Meditations Descartes points to a positive methodological use of philosophical doubt. It is a tool through which the nature and source of knowledge can be clarified. It reveals assumptions and premises that may have lurked unstated. Philosophical doubt throws into stark relief our relation to the world, a relationship that can be cast in terms of what we know.

According to Descartes only those beliefs which are indubitable can provide the basis for our knowledge of the world. To identify those beliefs we must cast the net of doubt as wide as we can in a process of eliminating those beliefs ill-suited to playing the foundational role. In employing the method of doubt Descartes provided philosophy with its most influential set of sceptical arguments in the unreliability of the senses, the dreaming argument, the possibility of systematic deception (demons and brains in vats). In each of these cases it is possible that my belief that p is false even though all the evidence appears to support it. My grounds for saying I know that p are undermined by the possibility that the belief could be the product of a defeating condition such as perceptual error, dreaming or deception. While it is important to note that Descartes employs sceptical worries as tools, more radically, and in ways that helped to shape the development of modern philosophy, sceptical arguments can be deployed to suggest that we face a real epistemic problem in the form of the gap between what we believe and our best grounds for believing. The sceptical challenge is whether are entitled to talk in terms of knowledge at all.

4. Global Scepticism

The strongest sceptical claim is the global claim that everything can be doubted, or that nothing can be known. On its face this might seem an especially unpromising position, perhaps better suited to the realm of caricature. The very claim is self-defeating. It undermines itself. The global sceptic makes a claim about the impossibility of knowledge, which is surely to cast doubt on the claim itself. In other words we can ask the sceptic if he or she knows nothing. An affirmative answer is just to say that one does know something (viz. that they can know nothing/everything can be doubted), and so the devilish idea of global scepticism disappears in its own contradiction.

Or is this too fast? The sceptic may just shrug his shoulders. His purpose is to undermine our conviction that knowledge is possible. Rather than settle for the "Academic" conclusion that knowledge is impossible, he makes the "Pyrrhonian" claim that one has to suspend judgment on whether knowledge is possible. This is enough for him but clearly not enough for those of us who think knowledge is both important and possible.

Leaving the self-defeating nature of the claim to one side for the moment, it is clear that whether we are dreaming or in the Matrix or being deceived by a demon (or whatever), then we can be sure of at least one thing. That is, we can be sure that we are thinking - at least at the moment when I attend introspectively to the contents of my thought. Having generated the exaggerated or "hyperbolic" doubt of the demon, Descartes finds a starting point for establishing the sure and certain foundations of knowledge in the realisation that the proposition "I am, I exist" is necessarily true whenever proposed or conceived by oneself. This step in the overcoming of doubt is known as the Cogito. It is a claim that Descartes makes in different ways in his Discourse on Method (1637), Meditations (1641) and again in a later work, Principles of Philosophy (1644).

But immediately I noticed that while I was trying thus to think everything false, it was necessary that I, who was thinking this, was something. And observing that this truth "I am thinking, therefore I exist" was so firm and so sure that all the most extravagant suppositions of the sceptics were incapable of shaking it. I decided that I could accept it as the first principle of the philosophy I was seeking.[4]

But I have convinced myself there is absolutely nothing in the world, no sky, no earth, no minds, no bodies. Does it follow that I too do not exist? No: if I convinced myself of something then I certainly existed. But there is a deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case I too undoubtedly exist if he is deceiving me; and let him deceive me as mush as he can, he will never bring it about that I am nothing so long as I think that I think I am something. So after considering everything very thoroughly, I must finally conclude that the proposition "I am, I exist" is necessarily true whenever it is put forward by me or conceived in my mind.[5]

A related point is that even if I come to systematically doubt that my experiences are actually veridical (true), I don't seem able to doubt that I am having certain experiences. I may have an experience of seeing a tree and doubt that it is real. Yet, how do I doubt that I am having the experience as of seeing the tree? Likewise, I may not know that I'm not a brain in a vat, but I cannot doubt (as it happens) that I believe I am not.

The possibility of global scepticism is also challenged by a class of truths it seems unreasonable to doubt. Here we can think of fundamental logical and mathematical and geometrical propositions. Perhaps, though, the sceptic can challenge us to say exactly when or how such beliefs are immune from doubt. I may not doubt that 2+2=4 when I am doing the calculation, but can I rely on my memory that the answer is 4?

5. Doubt and the External World

Let us grant that certain things appear to be beyond the reach of philosophical doubt. For example the denial that triangles have three sides appears self-contradictory. Self-evident truths (tautologies) may be immune from philosophical doubt, but this may strike you as rather trivial in the face of what can be doubted. We are faced by a rather serious problem if philosophical doubt can call into question whether our everyday experience of the world is "real". That is, for present purposes, whether we have knowledge of a world that is independent of us and for the most part pretty much as it seems. If you don't think that this is a problem imagine what it is like to live as a sceptic (really).

In the second part of this paper we shall sketch three influential responses to scepticism about the external world proposed in the twentieth century by Moore, Wittgenstein and Putnam. Each wants to retain our commonsense, ordinary understanding of our epistemic relationship to the world while respecting the force of the sceptical challenge.

6. G. E. Moore

Moore was greatly interested in scepticism. He argued in a number of places that scepticism about the external world was provably false.[6]

Perhaps the most famous argument Moore gives is his "Two Hands" argument in his paper "Proof of an External World". Picture Moore standing before you and saying, "Here is one hand", as he makes a gesture to indicate his right hand and then, "and here is another", as he makes a gesture to indicate the left. From this it follows, says Moore, that two human hands exists at that moment. Hands are ordinary physical objects-"things"-that are features of what we call the "external world". So, if hands exist, then so too does the external world.[7]

As Moore has it, the argument is then simply this:

Here is one hand and here is another.
Two human hands exist at this moment.

We may put the argument in a slightly more detailed form as follows:

If you can prove the existence of at least two ordinary things, then you have proved the existence of an external world.
Here is one hand (shows left hand).
Here is another hand (shows right hand).
Hands are things.
There are two things (at this moment).
There is an external world (at this moment).

Now, anyone seeing either argument for the first time can be forgiven for thinking that Moore has missed the point. If it were that easy to defeat the sceptic, then why would it have taken over two thousand years for someone to have done it? Now, Moore was no fool and it is generally a good idea when interpreting the words of an intelligent person to assume they were saying something interesting and complex. So, what was Moore up to?

Moore rightly says that his argument (and the longer version) satisfy three conditions on a good argument. First, every premise of an argument must be different from the conclusion. For if the conclusion of an argument is already assumed as a premise, you prove nothing, or the argument is circular. Second, the premises have to be known if the conclusion is to be something known. Third, the conclusion has to follow from the premises. The first and third conditions are certainly satisfied. What about the second?

Moore says that sceptic will say the following. "You first need to prove that you know that this is a hand and so is that. And you didn't. And you can't." Moore agrees that he did not and cannot. He writes:

In order to do it [prove the premise], I should need to prove, for one thing, as Descartes pointed out, that I am not now dreaming. But how can I prove that I am not? I have, no doubt, conclusive reasons for asserting that I am not now dreaming; I have conclusive evidence that I am awake; but that is a very different thing from being able to prove it. I could not tell you what all my evidence is; and I should require to do this at least in order to give you a proof.[8]

Moore continues by saying that the sceptic will say that without such a proof the premises, the proof Moore has given is no proof at all. This, Moore says, is a "definite mistake".[9] Moore's point seems to be this. Any proof starts with premises. If the premises themselves can be proved, then they will be the conclusions of arguments with other premises. Ultimately, one will reach premises that can't be proven but can still be known because we have conclusive evidence.

Any proof or any theory must assume basic premises or axioms that don't admit of further proof. Intuitively, you have to start somewhere if you are to get anywhere else. So, there's a sense in which Moore is right to say that you can't keep asking him to prove everything he claims to know. This might tempt the sceptic to "mirror" Moore's thinking. Moore says, "I have conclusive reasons in virtue of which I know that this is a hand but I can't prove this. The sceptic replies, "I have conclusive reasons in virtue of which I don't know that this is a hand but I can't prove this. So we're even." But this can't be quite right. If the sceptic has conclusive reasons for something, then it seems he should know it. But the sceptic says he doesn't know anything. Instead, we should understand the sceptic as saying that he has good reasons for thinking that knowledge is impossible without being sure they're good enough. But the fact that the reasons cast doubt on the possibility of knowledge means that Moore cannot simply say that he has conclusive evidence. He has to tell us more about what it is.

How does Moore respond? Moore's strategy, most clearly visible in two other papers, "Four Forms of "Scepticism" and "Certainty", is to claim that there is no good reason to believe the sceptic and that the supposed stalemate between him and the sceptic is broken in his favour because his view is the ordinary view of common-sense. Philosophers such as Descartes, Berkeley, Hume and Kant said very different things in response to the sceptic but they all agreed that there was a problem to be answered. (Indeed, Kant called it a "scandal" that something so obvious as the existence of the external world remained unproven.)[10] Moore's strategy is to deny that there is a problem to be answered.

Let us consider Moore's response to Descartes' idea that there could be a malicious demon.[11] Moore's colleague Bertrand Russell admitted that the demon was a logical possibility and that nothing could be known for certain beyond the contents of one's own immediate experience.[12] I am currently experiencing a red, cylindrical shape. I can know that this is my experience. I can't be certain, however, that I am experiencing a red pencil because my experience could be generated by the demon. Moore replies by pointing out that, ordinarily, we claim to know things on the basis of how things seem and how they have seemed in the past. Ordinarily, I would say that I know that I see a pencil because I know I am having an pencil-experience now and I know that I've had pencil-experiences in the past in virtue of which I learned that these sort of things are pencils. So, Russell tells us that we can't be certain about the existence of things on the basis of experiences and Moore tells us that we can. There's a stalemate. Russell does not have a winning argument that makes the demon a live possibility. Moore then challenges us. Which are you more certain of? That you know you're seeing a pencil? Or that the malicious demon might be fooling us? Surely we are more certain that we do have knowledge than we are of the possibility of a strange demon (or a Matrix) fooling us.

In another passage, Moore compares the sceptic who says that, since we don't know we're not dreaming, we can't know anything about external world now, and the common-sense philosopher, who says, since we do know lots of things about the external world now, we can know we're not dreaming:

[What] if our sceptical philosopher says...:It is logically possible both that you should be having all the sensory experiences you are having, and also that you should be remembering what you do remember, and yet should be dreaming. If this is logically possible, then I don't see how to deny that I cannot possibly know for certain that I am not dreaming...But can any reason be given for saying that it is logically possible? So far as I know nobody ever has, and I don't know how anyone ever could. And so long as this is not done my argument, "I know that I am standing up, and therefore I know that I not dreaming", remains at least as good as his [the sceptic's], "You don't know that you are not dreaming, and therefore don't know that you are standing up". And I don't think I've ever seen an argument expressly designed to show that it is not.[13]

So, if it could be shown that we cannot know that we are not dreaming, then the dreaming hypothesis would be a logical possibility. But Moore stands firm: no-one has ever given him a convincing enough reason to doubt what he knows. But why should the stalemate be broken in Moore's favour? Moore points out that we use the verb "know" and verbs like "see" and "remember" with great success. (Successful use of "to see" implies the existence of what we see, hence an external world, and successful use of "to remember" implies that we know what happened in the past.) So, the balance of opinion should be in favour of common-sense. The sceptic has the burden of proof. Under English law, when someone is tried for an offence, the scales of justice are not equally weighted at the start between innocence and guilt. There is a presumption of innocence and the burden is on the prosecution to prove the defendant guilty. In a similar way, Moore argues that common-sense is innocent until proven guilty. Is Moore correct? This is not a matter we will pursue. The question is whether common-sense wins in a philosophical context. Of course it wins in an everyday context: you cannot plead your innocence to an offence by saying that everything is a dream. If the sceptic can do enough to convince us that there is the slightest philosophical worry about knowledge, Moore's robust denials will fail.[14]

7. Ludwig Wittgenstein

Wittgenstein turned to the problem of scepticism later in what turned out to be the last eighteen months of his life.[15] Moore's influence is clear from the opening line of his collected thoughts on knowledge, On Certainty: 'If you do know that here is one hand, we'll grant you all the rest.'[16]

Wittgenstein's writings are not easy to interpret. Despite On Certainty reading a lot more fluidly than much of Wittgenstein's work, a single, coherent thesis is hard to discern. In what follows, we'll outline various strands of Wittgenstein's thought and draw a general conclusion.

Moore thought that an utterance of the sentence, "I know I have hands" expresses something ordinary and true. It is a perfectly acceptable use of the verb "to know". Wittgenstein does not say that it is an unacceptable use in the sense a sceptic might but he does say that it is unacceptable in another sense. It is unacceptable in ordinary speech because it suggests that there is something potentially uncertain which one is in fact sure about. If something can be known, it can be doubted. Unlike the sceptic and unlike Moore, Wittgenstein says that not all our beliefs are things susceptible to knowledge and doubt. There are some truths so basic that they cannot be denied on pain of incoherence.

These basic truths, or propositions, that form what Wittgenstein calls "the scaffolding of our thoughts" (§211). They are propositions like "every human being has parents" (§211) and "motor cars do not grow out of the earth" (§279). They create a framework or backdrop that makes enquiry - assessing whether something is true or false and subsequently whether it is known or not - possible. A useful image here is a laboratory. In our laboratory we have a microscope through which we view bacteria to see whether they are of type A or type B. When we are investigating the bacteria we must be assuming that the microscope is working. It is part of our background. You can only say whether a bacteria is of type A or type on the presumption that it is beyond question that the microscope is working.

Wittgenstein writes, for example:

...We check the story of Napoleon, but not whether all the reports about him are based on sense-deception, forgery and the like. For whenever we test anything, we are already presupposing something that is not tested. Now am I to say that the experiment which perhaps I make in order to test the truth of a proposition presupposes the truth of the proposition that the apparatus I believe I see is really there (and the like)? (§163)

One cannot make experiments if there are not some things that one does not doubt. But that does not mean that one takes certain presuppositions on trust. When I write a letter and post it, I take it for granted that it will arrive - I expect this.
If I make an experiment, I do not doubt the existence of the apparatus before my eyes. I have plenty of doubts but not that. If I do a calculation I believe, without any doubts, that the figures on the paper aren't switching of their own accord, and I also trust my memory the whole time, and trust it would it without any reservation... (§337)

In terms of our image, Wittgenstein does not deny that it is ever possible that the microscope is not working. Of course a microscope can malfunction. We calibrate microscopes using a device we may call a microscope-checker. Now, in so doing, we must assume that it is working properly. To check it, we would need a microscope-checker-checker and to assume that it is working...and so on.

Understood this way, Wittgenstein is saying that knowledge and doubt require a context and in any context, there are necessarily truths beyond knowledge and doubt. The claim such as "I have hands" is an example of such a basic truth. Moore is not exactly wrong to say that he knows this but it is at the very least inappropriate. Wittgenstein writes:

Even if the most trustworthy of men assures me that he knows things are thus and so, this by itself cannot satisfy me that he does know. Only that he believes he knows. That is why Moore's assurance that he knows...does not interest us. The propositions, however, which Moore retails as examples of such known truths are indeed interesting. Not because anyone knows their truth, or believes he knows them, but because they all have a similar role in the system of our empirical judgments. (§137)

It is inappropriate because it is not the sort of thing that can ordinarily be doubted. It is as if Moore does enough by saying, "I have hands" - the "I know" is superfluous.

We said "ordinarily. Does it mean it can be doubted? Wittgenstein seems to say that anything can be doubted but not equally so. In order to doubt something like "I have hands", a very special context is needed. For example, in §23, he considers someone whose arms are in bandages, perhaps after an accident. This person may meaningfully say, "I know I have hands" because the context of the accident and (let us suppose) lack of feeling when he comes round mean he genuinely can doubt whether he still has hands under those bandages.

If anything can be doubted, doesn't that mean that everything can be doubted? Not obviously. There's a logical error in the argument from "it is possible to doubt anything (any one thing)" to "it is possible to doubt everything". Compare, for example, the argument from "it is possible that any of the ten competitors will win the race" to "it is possible that all the ten competitors will win the race."[17] Wittgenstein is not making a narrow logical point, however. He is making the conceptual point that doubt loses all meaning if you try to doubt everything. In the same way, it would be impossible for everyone to lie constantly: lies work only against a background of truth. As Wittgenstein writes:

If you tried to doubt everything you would not get far as doubting anything. The game of doubting itself presupposes certainty. (§115)

Is anything beyond doubt? It seems Wittgenstein is both tempted by the idea that there are and that there aren't. He writes, for example:

If someone doubted whether the earth had existed a hundred years ago, I should not understand this, for this reason: I would not know what such a person would still allow to be evidence and what not. (§231)

For months I have lived at address A, I have read the name of the street and the number of the house countless times, have received countless letters here and given countless people the address. If I am wrong about it, the mistake is hardly less that if I were (wrongly) to believe I was writing Chinese and not German. (§70)
If my friend were to imagine one day that he had been living for a long time past in such and such a place etc. etc., I should not call this a mistake, but rather a mental disturbance, perhaps a transient one. (§71)
Not every false belief of this sort is a mistake. (§72)
But what is the difference between mistake and mental disturbance? Or what is the different between my treating it as a mistake and my treating it as a mental disturbance?(§73)
Can we say: a mistake doesn't only have a cause, it also has a ground? I.e. roughly: when someone makes a mistake, this can be fitted into what he knows aright. (§74)

Here, Wittgenstein suggests that doubts and mistakes are possible because they are understandable. We know what it would be to be in doubt - and how to correct it. If someone doubts too much, we conclude that they are not mistaken but mad. In a very revealing series of passages, he writes:

It might be imagined that some propositions, of the form of empirical propositions, were hardened and functioned as channels for such empirical propositions as were not hardened but fluid; and that this relation altered with time, in that fluid propositions hardened and hard ones became fluid. (§96)
The mythology may change back into a state of flux, the river-bed of thoughts may shift. But I distinguish between the movement of the waters on the river bed and the shift of the bed itself; though there is not a sharp division of the one from the other. (§97)
But if someone were to say "So logic too is an empirical science" he would be wrong. Yet this is right: the same proposition may get tested at one time as something to test by experience, at another as a rule of testing. (§98)
And the bank of the river consists partly of hard rock, subject to no alteration or to only an imperceptible one, partly of sand, which now in one place now in another gets washed away, or deposited. (§99)

Here Wittgenstein wants to say that there are foundations - "a river-bed of thoughts subject to no alteration" but also to resist it "the river-bed may shift", "subject...to only an imperceptible one." Again, consider the following passage in which the contextualism and tension between foundationalism and anti-foundationalism come out clearly:

Admittedly, if you are obeying the order "Bring me a book", you may have to check whether the thing you see over there really is a book, but then you do at least know what people mean by "book"; and if you don't you can look it up,- but then you must know what some other word means. And the fact that a word means such-and-such, is used in such-and-such a way, is in turn an empirical fact, like the fact that what you see over there is a book.
Therefore, in order for you to be able to carry out an order there must be some empirical facts about which you are not in doubt. Doubt itself rests only on what is beyond doubt.
But since a language-game is something that consists in the recurrent procedures of the game in time, it seems impossible to say in any individual case that such-and-such must be beyond doubt if there is to be a language game-though it is right enough to say that as a rule some empirical judgment or other must be beyond doubt. (§519)

This passage brings us to the importance of language and "language-games". The importance of a correct understanding of language to philosophy is the central theme of the later Wittgenstein's writings. In On Certainty, Wittgenstein suggests that our language - our grasp of meaning - is part of the scaffold or foundation or river-bed.

The truth of my statements is the test of my understanding these statements. (§80)
That is to say: if I make certain false statements, it becomes uncertain whether I understand them. (§81)

If you are not certain of any fact, you cannot be certain of the meaning of your words either. (§114)

Here, Wittgenstein seems to be saying the following. There is not a sharp difference between grasping the truth of statements and grasping their meaning. We understand certain statements because they are true. The world, as it were, gives our words meaning. If so, then to try to doubt the existence of the external world would be to doubt the meaningfulness of language. At this point, any sceptic who even thought language may be meaningless would be dismissed by Wittgenstein. It is absurd to deny that our words (and thoughts) lack meaning and it would mean that the sceptic is in fact saying nothing at all.

There is one final strand to weave into the picture. We have just seen how language and basic truths are woven together to serve as a foundation or scaffold. In addition, there is action. What are the foundational truths? What makes it reasonable to believe something? Sometimes we ask for evidence to justify a claim but this cannot go on forever on pain of nothing ever being justified. But Wittgenstein has argued that this idea is incoherent. Something can only be considered for justification against a background of beyond-justification truths. Furthermore, as we have just seen, to say that no belief is justified would mean that we have no firm grip on our language either, which cannot be.

A foundational truth cannot be one that everyone believes or that the "experts" of a community believe. For history shows that we have been wrong - massively wrong- in the past. Wittgenstein writes that he is convinced "that the sun is not a hole in the vault of heaven." (§104) despite this being once the belief of certain philosophers in antiquity. Wittgenstein writes that our knowledge of the world increases all the time and hence our foundation in this sense grows. But, more fundamentally than our scientific knowledge, is our everyday knowledge revealed in language and action:

The picture of the earth as a ball is a good picture, it proves itself everywhere, it is also a simple picture - in short, we work with it without doubting it. (§157)

Sure evidence is what we accept as sure, it is evidence that we go by in acting surely,acting without any doubt. (§196)

Giving grounds, however, justifying the evidence, comes to an end;-but the end is not certain propositions" striking us immediately as true, i.e. it is not a kind of seeing on our part; it is our acting, which lies at the bottom of the language game. (§204)

At the foundation of well-founded belief lies belief that is not well-founded. (§253)
Any "reasonable" person behaves like this. (§254)

The key phrases here are underlined. The meaningfulness of our language is shown by our successful interaction with each other and the world beyond. For example, the meaningfulness of 'Can you bring me a book?' is shown by another person understanding it, hence showing knowledge of what books are and so forth, and bringing you that bit of the world you desire.

For Wittgenstein, language, belief and action are intertwined with the world in such a way that it makes it impossible coherently to doubt that any one of the four parts is malfunctioning on a global scale. The coherence of language shown through shared beliefs and actions means that doubt about the world with which we interact is impossible. In a similar way, to suppose an external world, meaningful language, successful actions but all our beliefs to be false is impossible. As is the supposition that there's a world, meaningful language, many true beliefs and unsuccessful action. As, finally, is the supposition that there's an external world with which we interact successfully, have many true beliefs about but where our language is meaningless or whose parts mean something radically different.

But, as we have seen, Wittgenstein has doubts about whether there really are foundations. Couldn't a sceptic suggest that all four parts mentioned above would mesh properly together in a suitably-detailed virtual world? Our actions would be virtually-realised, our beliefs true of a virtual world, a virtual world would indeed exist and our language would be meaningful within the world...and yet our belief that this really is the really world would be false. Or is this just to repeat with a technological gloss a bad idea that Wittgenstein has closed off? In other words, has Wittgenstein shown that it could only be the real world that we could be interacting with and finding out about to the level of detail and complexity familiar to us?

8. Conclusion: The worry persists?

Neither of the arguments clearly stops the determined sceptic from claiming that there remains a potential gap between our best grounds for believing that the world is thus and so and the truth of such claims. We might follow Hume in questioning whether we can really take sceptical arguments seriously.[18] Perhaps we are such that we just go on as if our experience of the world is a reliable guide and source of knowledge. The sceptic tells us things could be otherwise, but this is a claim we can neither defeat with philosophical argument nor are (really) capable of taking seriously. This is not to say that the question is not a serious one about our epistemological relationship to the world. Rather, it is fact about our nature that (in our everyday lives) we cannot help but believe in causation, inductive reasoning and the external world. You may feel that this is somehow an evasion of the problem. Perhaps we should question whether our warrant inclaiming to know there is an external world does not require the certainty that would close the gap between evidence and belief.

This is an issue we shall pursue another time. In a successor article, we shall consider responses to scepticism provided by two philosophers of the latter half of the twentieth century, Donald Davidson and Hilary Putnam.

Matthew Carmody and Paul Sheehy
Richmond-upon-Thames College



[1]  We do not know exactly when Sextus Empiricus was born or when he died. He was active around 200 CE.  [back] 

[2]  As with so many philosophers from antiquity, we have very little material with which to work with to know exactly what they thought. The main source of evidence for Pyrrho's thought is a summary of an account of Pyrrho's philosophy written by his follower Timon. Experts disagree over how to interpret the passage. For some, Pyrrho was arguing that reality itself is "indeterminate", meaning that we cannot ever come to know it in any determinate way and hence in any meaningful way at all. On this "metaphysical" interpretation, Pyrrho is not really a sceptic. The problem is not that we are blocked from coming to know what reality is like. It is rather that reality itself is not something that can be known. On the "epistemological" interpretation, Pyrrho is the sceptic arguing that we cannot come to know reality. The problem now is with our capacities for knowledge.
      For two extremely good articles, to which the present fnote is indebted, on ancient scepticism and Pyrrho, see:


[3]  The Greek terms for the suspension of judgment and the balance of judgments are "epoche" and "isosthenia" respectively.   [back] 

[4]  Discourse (1637). The original version was published in French, so the text read "Je pense, donc je suis". In the 1644 Latin translation of the Discourse and the Principles published in the same year we find the famous Latin version - cogito ergo sum.  [back] 

[5]  Meditation II(1641)  [back] 

[6]  1873-1958. Born in Upper Norwood, he studied at Cambridge where he later became Professor of Mental Philosophy and Logic. The four key papers "A Defence of Common Sense", "Proof on an External World", "Four Forms of Scepticism" and "Certainty" are all in Moore's Philosophical Papers (1959) London: George Allen and Unwin. All page references are to this volume. For more on Moore, see Philosophy Pages: Moore  [back] 

[7]  See "Proof on an External World", pp. 145-6.  [back] 

[8]  Proof of an External World", p. 149.  [back] 

[9]  "Proof of an External World", p. 150.  [back] 

[10]  "It still remains a scandal to philosophy and to human reason in general that the existence of things outside us (from which we derive the whole material of our knowledge, even of our inner sense) must be accepted merely on faith, and that if anyone thinks good to doubt their existence, we are unable to counter his doubts by any satisfactory proof." Critique of Pure Reason, Preface to the Second Edition, p. xxxix  [back] 

[11]  "Four Forms of Scepticism", pp. 223-6.  [back] 

[12]  Moore looks at Russell's consideration of Descartes' sceptical hypotheses in Russell's An Outline of Philosophy (1927) London: George Allen and Unwin.  [back] 

[13]  "Certainty", p. 250.  [back] 

[14]  An excellent chapter discussing Moore in more detail in an excellent book on Scepticism, is chapter 5 of Barry Stroud's The Significance of Philosophical Skepticism (1984) Oxford University Press.  [back] 

[15]  1889-1951. Born in Vienna, Wittgenstein did most of his philosophical work at Cambridge. For more on Wittgenstein, see Philosophy Pages: Wittgenstein  [back] 

[16]  On Certainty (1975). Oxford: Blackwell Publishing.  [back] 

[17]  In logical notation, (x)◊(Winner(x)) does not entail ◊(x)(Winner(x)). We should observe that "it is possible that any of the competitors will win the race" allows the possibility that all of them do, by being joint winners. If we want to say that it is possible that any of the competitors could be the unique winner, we would have to write: ◊(x)[Winner(x) & (y)(y≠x &~ Winner(y))]  [back] 

[18]  See e.g. Hume's Enquiries Concerning Human Understanding §§117-123  [back]