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Ludwig Wittgenstein came to Cambridge in 1912 in order to study under the supervision of Bertrand Russell. It was the beginning of seven years of intensive and single-minded research in logic and philosophy which resulted in the only book Wittgenstein published in his lifetime, the Tractatus Logico-Philosophicus. It is not to the present purpose to investigate the wide range of philosophical views embodied in that work, but rather to examine the conception of philosophy propounded in it. In order to do so, some appreciation of Wittgenstein's intellectual background and the problem-setting context of his work is necessary. For a twenty-three-year-old research student of philosophy, Wittgenstein in 1912 was remarkably ill-read in the history of the subject. His intellectual milieu was that of a highly cultured and sophisticated member of the Viennese intelligentsia. His training was, however, scientific. In 1906 he had begun studying engineering in the Technische Hochschule in Berlin-Charlottenburg, and in 1908 he came to Manchester to pursue research in aeronautics. In the course of research into the design of a jet-reaction propeller he was led from dynamics to pure mathematics, and from there to logical and philosophical investigations into the foundations of mathematics. He apparently read Russell's Principles of Mathematics and was greatly impressed by this imposing work which had, significantly, germinated in theoretical problems in dynamics. It was probably the appendix to the Principles of Mathematics which led Wittgenstein first to read the works of Frege, and then to visit him. On Frege's advice he returned to England to study under Russell.
Wittgenstein, like any well-educated Viennese at the turn of the century, had read Schopenhauer in his teens. He is reported to have been greatly impressed, and he told von Wright that his first philosophy was a Schopenhauerian epistemological idealism. It was not, however, a Schopenhauerian interest which brought him to philosophical investigation. Although Schopenhauer's influence upon the later sections of the Tractatus is profound, it is clear from Wittgenstein's correspondence with Russell, from the 1913 and 1914 notes on logic and from the three remaining philosophical notebooks covering the periods from 22 August 1914 to 22 June 1915, and from 15 April 1916 to 10 January 1917, that the driving force behind his investigations was logic and its metaphysical implications.
On 29 September 1914 Wittgenstein, in his notebook, referred to the fact that in law courts in Paris a motor car accident is represented by a model employing toy cars and figures. It struck him that there is not merely an analogy between the way such a model represents the facts of the accident and the way a proposition represents a situation, but rather that a model, a picture, a proposition are severally special cases of representation and must share certain common features in virtue of which they can represent whatever it is that they represent. In all such cases the representation must, in some way, be co-ordinated with what it represents. Yet, it may represent falsely, for things may not be related as it represents them as being. Rather, as in the model, ‘a world is as it were put together experimentally’ (NB, p. 7). The representation can be true or false, but it must have a sense independently of its truth or falsehood, it must represent a possible configuration of things even if not an actual one.
From this seed grew the famous picture theory of meaning for which the Tractatus is best known. It is important, however, not to exaggerate the importance of the new idea that a proposition is a picture, a logical picture, of a situation. A great many of the ingredients of the Tractatus conception of meaning and representation had occurred to Wittgenstein well before this idea crossed his mind. It enabled him to weld together into a unified whole the thoughts which he had been developing since 1912, as well as leading to what seemed to be fresh insights. I shall try to give a brief sketch of the central points of the picture theory.
First, bear in mind some of the antecedent commitments. The most fundamental was the idea of the bipolarity of the proposition. This had occurred to Wittgenstein very early. While he had never thought Frege right in saying that propositions refer to truth-values, he did originally think that a proposition refers to a fact (has a fact as its Bedeutung or meaning).
The structure of this book can best be captured by means of a theatrical metaphor. The book has, as it were a central drama, a set, and a back-cloth. The subject with which I am primarily concerned, the drama which is enacted throughout the book, is Wittgenstein's metaphysics of experience. This Kantian term of art is chosen advisedly, for one of the leitmotifs consists in exploring the Kantian affinities of Wittgenstein's philosophy in general, both in the Tmctatus and in the post-1929 works. Wittgenstein's metaphysics of experience can be seen as consisting of a triad of problems, two of which are examined comprehensively. These are: self-consciousness, our knowledge of other minds, and our knowledge of objects. The secondary concern of the book, the set upon which the main drama takes place, is Wittgenstein's general conception of philosophy. This theme is intended to illuminate, and be illuminated by, the examination of Wittgenstein's metaphysics of experience. For the latter, particularly in Wittgenstein's later work, is an exemplification of his conception of the task, process, and result of philosophical investigation. As my work progressed, it became increasingly clear that the back-cloth against which the two main subjects had to be seen could not be wholly neglected. The back-cloth consists of the development of his semantic theories from the strict realism of the Tractatus to the constructivistinspired conventionalism of the Philosophical Investigations. I have explored this most difficult subject only so far as seemed to me necessary in order to grasp the nature of Wittgenstein's metaphysics of experience, his general contribution to epistemology, and his conception of philosophy. So the back-cloth is, as is customary in stage design, uneven. In parts it is filled in with colourful detail, at other points it is rough and ready.
Wittgenstein is almost unique among philosophers in having produced two complete philosophies, the later containing substantial criticism and repudiation of the earlier. The controversy over the degree of change and the degree of constancy will doubtless rage for many years to come. With respect to the subjects with which I am concerned in this book I have tried to plot both transformation and continuity. It is certainly impossible to understand Wittgenstein's later concern with and refutation of solipsism and idealism without seeing its roots in his fascination with Schopenhauer in the Notebooks 1914-16 and the ‘methodological solipsism’ of the Philosophische Bemerkungen.
In Chapter V it was noted that in the Philosophical Remarks, during Wittgenstein's brief verificationist phase, he distinguished between ‘genuine propositions’ and ‘hypotheses'. Genuine propositions, he argued, are sense-datum statements that are immediately and conclusively verified by reference to current experiences, compared directly with reality for their truth. Hypotheses (e.g. statements about material objects, the past or future, laws of nature) are not propositions in this sense, but quite different kinds of grammatical structures. They are not conclusively verifiable at all, not compared directly with reality for their truth. They are supported by evidence, viz. ‘symptoms', although no accumulation of such evidential support will render a hypothesis certain. So it makes no sense to talk of a hypothesis as certain. Symptoms stand to the hypothesis they support as points on a curve to a curve. The symptoms/hypothesis relation is grammatical not empirical (inductive). For that certain symptoms probabilify a hypothesis partially determines the meaning of the hypothesis. Since any set of symptoms falls short of entailing the hypothesis, the evidential support it gives is defeasible. For addition of further genuine propositions to the set of symptoms for a given hypothesis may undermine the plausibility of the hypothesis.
We saw that Wittgenstein rapidly abandoned this conception. He came to think that what he had conceived of as ‘genuine propositions’ are not compared with reality for truth and falsehood. There is no verification of i have toothache’ or ‘A looks red to me', and the role of such expressions is not to describe how things are. Such ‘propositions', far from being known with certainty, cannot be said to be known at all. Similarly, propositions such as ‘This poppy is red', ‘The book is on the table’ cannot be said to be hypotheses if that means that they are at best merely probable or that they cannot be conclusively verified. It only makes sense to talk of something's being probable where it also makes sense for it to be certain.
As the symptom/hypothesis relation disappears from Wittgenstein's writings in 1932/33 we find the first occurrences of the term ‘criterion'. It crops up initially in contexts in which emphasis is being given to verification. A statement gets its sense, Wittgenstein argued at this stage, from its verification (AWL, p. 17).
Insight and Illusion is a thoroughly comprehensive examination of the evolution of Wittgenstein's thought from the Tractatus to his later 'mature' phase. This is a reprint of the revised and corrected 1989 edition, with a new foreword by Constantine Sandis. Hacker’s book is now widely regarded as the best single volume study covering both the 'early' and the 'later' Wittgenstein. Until this third edition, the book had been out of print for twenty-five years.
The portable guide takes the reader through the major themes and concepts in Wittgenstein's works. In the name of exhaustiveness, these include: the so-called picture theory of meaning; the say/show distinction; the principle of verification; anti-metaphysics; anti-scientism; tautologies; the nature of mathematical propositions; ordinary language and nonsense; the law of the excluded middle; the Augustinian picture of language; knowledge and certainty; explanation and understanding; volition and the will; the relation of meaning to use; ostensive definition; ownership of experience; the first-person pronoun; the inner/outer; philosophical psychology; anti-solipsism; forms of life; the so-called private language argument; the autonomy of grammar; language games; and rule-following.
In so doing, Hacker gives us a picture of Wittgenstein's intellectual development: from his early conception of philosophy (influenced by thinkers as varied as the likes of Schopenhauer, Hertz, Boltzmann, Frege, and Russell), through the 'middle period', which began with his return to philosophy in 1929, to his later work.
In the course of the fifteen years since I wrote Insight and Illusion I have continued to study and write about the philosophy of Wittgenstein. During this period many further volumes culled from his voluminous Nachlass, as well as lecture notes taken by his students, have been published and, indeed, the whole of the Nachlass has been made available in xerox. This extensive material illuminates countless aspects of his better known works, in particular the Tractatus and Philosophical Investigations, and the results of researches into it were incorporated in two volumes I wrote together with Dr G. P. Baker on the Philosophical Investigations, viz. Wittgenstein: Understanding and Meaning (1980) and Wittgenstein: Rules, Grammar and Necessity (1985). As I struggled to understand the thoughts of ‘the first philosopher of the age’ I came to recognize that on many issues I had previously misunderstood him, sometimes as a result of reading his works through the spectacles of Oxford philosophy and its preoccupations in the 1960s. When I was offered the opportunity to produce a revised second edition of Insight and Illusion, I welcomed the chance to correct, in the light of this subsequent research, the distorted picture I had earlier sketched. For not all struck me as hopeless, and it seemed worthwhile to set the record as straight as I could. This did, however, mean that I was committed to very extensive rewriting.
In the Preface to the first edition I compared the structure of the book to the elements of a theatrical production, with a central drama, a set, and a back-cloth. Surveying the production afresh, it did not seem as flawed as Hamlet without the Prince, but the back-cloth, which consisted of a sketchy presentation of Wittgenstein's conception of meaning, looked more like Piccadilly Circus in the rush-hour than Elsinore Castle. I had been much impressed with the idea that it is illuminating to view the Tractatus as a paradigm of realism or truthconditional semantics, and the Investigations as informed by a wholly different approach to meaning inspired by constructivism or intuitionism in mathematics, namely anti-realism or assertion-conditions semantics.
The Tractatus is, inter alia, a dialogue with Frege and Russell, a dialogue in which, to a large extent, the voices of the two initiators are supposed to be familiar to the reader. Difficult to understand at best, it is quite impossible to follow without a grasp of the positions against which Wittgenstein was, often implicitly, arguing. Problems are compounded by three further factors. First, one must identify Wittgenstein's specific targets. Sometimes diey are to be found in Frege's Begriffsschrift, sometimes in The Basic Laws of Arithmetic or in his articles. In Russell's case Wittgenstein was not only criticizing the views propounded in The Principles of Mathematics, Principia Mathematica, and Our Knowledge of the External World, but often also views Russell never published and which only publicly came to light with the posthumous publication in 1984 of the suppressed 1913 manuscript entitled Theory of Knowledge. Secondly, one must beware of reading modern conceptions into these works. Though familiar technical terms such as ‘function', ‘truth-function', ‘truth-condition', ‘logical constant', ‘form’ occur in the writings of Frege, Russell, and the Tractatus, it must not be presumed that they are used in the same way or understood in the same manner as they are now. Otherwise one will misconstrue Wittgenstein's targets and misunderstand his criticisms. Thirdly, it is not enough to clarify how Frege and Russell used and construed their terms of art; one must make clear, when necessary, whether Wittgenstein, in criticizing them, interpreted them as they intended. An exhaustive record of this dialogue would pay rich dividends in terms of I shall merely sketch some of the main theories and outline some of the central arguments.
Wittgenstein sided with Frege against psychologism in logic. Logical analysis is wholly independent of introspective psychology. Analysis of mental processes of thought and association, investigation into the empirical nature of human understanding, explanations of our modes of acquisition of concepts in learning-theory all belong to psychology and are irrelevant to logic (TLP, 4.1121). Accordingly, like Frege, Wittgenstein brushed aside as irrelevant to logic a host of questions concerning the nature of understanding.
Wittgenstein's claims that a philosophical problem has the form—'I don't know my way about’ (PI, §123) and that his own purpose in philosophy was ‘to show the fly the way out of the flybottle’ (PI, §309) are notorious. What is less well known is that the archetypal fly in the original flybottle was the solipsist. In the ‘Notes for Lectures on “Private Experience” and “Sense Data“', written between 1934 and early 1936, Wittgenstein wrote:
The solipsist flutters and flutters in the flyglass, strikes against the walls, flutters further. How can he be brought to rest? (NFL, p. 300.)
The puzzles surrounding solipsism thus became for Wittgenstein a paradigm of the diseases of the intellect to which philosophers are so prone. The solipsist, like the idealist, is caught in the net of grammar, and by disentangling the knots tied by his futile struggles one can better understand Wittgenstein's conception of philosophy and its methods. His refutation of solipsism comes in three phases. The first stage is to be found in the writings and reports of the transitional period from 1929 to the academic year 1932/3. The Philosophical Remark is particularly important here, but the notes taken by Waismann and Moore are also significant. The second and most revealing phase of his concern with uncovering the errors of solipsism (in particular) and idealism (in general) is between 1933 and 1936. The Blue Book and ‘Notes for Lectures’ contain Wittgenstein's most important arguments in refutation of solipsism. The third and final phase finds its full expression in the Investigations, with some additional material in Zettel. Here the direct and overt interest in solipsism is diminished, and its place taken by the fully-developed argument against the possibility of a private language, a brief sketch of which had already appeared in the ‘Notes for Lectures'. Although solipsism is only indirectly alluded to, most of the arguments developed in the second phase reappear in highly condensed form in the Investigations and Zettel. The task of the present chapter is to trace the process whereby Wittgenstein gradually freed himself from metaphysical illusion. I shall first examine the intermediate period between the Tractatus and the Blue Book, and then show how the elegant and comprehensive refutation of solipsism and idealism emerged in the second, mature phase. The argument against the possibility of a private language will be examined in detail in the following chapter.
The two conceptions of philosophy in the Tractatus bear considerable affinities to Wittgenstein's later conception which evolved from 1929 onwards and found its final and polished expression in the Philosophical Investigations. There are also, however, deep differences which lie concealed in his semi-ironical use of similar remarks in both works. His oracular epigrammatical style lends itself to ambiguity. His liking for such masters of irony, paradox, and pun, as Lichtenberg, Kierkegaard, and Kraus should be a warning to the superficial reader. His repetition of Tractatus dicta frequently constitutes the re-employment of old bottles to hold new wine. The author of the Tractatus had, in the opinion of the author of the Investigations, succumbed to many kinds of deep philosophical illusion. On the flyleaf of Schlick's copy of the Tractatus, Wittgenstein is reported to have written: ‘Jeder dieser Satze ist der Ausdruck einer Krankheit'. (Each of these sentences is the expression of a disease.) The general conception of philosophy was accordingly distorted on many matters, necessitating reinterpretation and correction. Any attempt to trace out continuity and contrast between the earlier and later work with respect to the conception of philosophy must bear in mind the fact that the axis of reference of the whole investigation has been rotated around a fixed point (PI, §108). The need to grasp conceptual structures remains, but they are now conceived sub specie humanitatis.
In the course of the lectures in 1930-3 Wittgenstein claimed that philosophy as he was now practising it was not merely a stage in the continuous development of the subject, but a new subject (M, p. 322). Using a simile reminiscent of Russell's claims about logical analysis, Wittgenstein declared that with the emergence of his new style of philosophizing there was a ‘kink’ in the evolution of philosophy comparable to that which occurred when Galileo invented dynamics. He repeated the point in the Blue Book (BB, p. 28). His work, he wrote, is one of the heirs of the subject that used to be called philosophy. The important thing, he claimed in his lectures, was not whether his results were true or false, but that a new method had been found, as had happened when chemistry was developed out of alchemy.
By contrast with the philosophical ideals of the youthful Wittgenstein, the viewpoint of the mature Wittgenstein may well seem tarnished and disillusioned. The dramatic change in his conception of the relation between language and reality, of the structures of language, and of the logical structures of the world, led to a re-allocation of the metaphysical from the domain of ineffability, where it lay protected by a penumbra of necessary silence, to the domain of philosophical illusion, a fit subject for the pathology of the intellect. This seems a picture of philosophy fallen from grace. Our understanding of this transformation can be furthered by exploring Wittgenstein's later conception of grammar and its relation to reality. Although the change runs deep, it is instructive to view it in certain respects as a matter of rotating the axis of the investigation one hundred and eighty degrees around the fixed point of our real need (PI, §108). In the Tractatus the essence of language or thought provided the insight into the structure of reality. In the Investigations the essence of language is still, in a qualified sense, the subject of investigation (PI §92). Moreover it might still be said to be isomorphic with the ‘structure of reality’ (for the proposition that P does indeed correspond to the fact that P, if it is true), not because language must mirror the logical form of the universe, but because the apparent ‘structure of reality’ is merely the shadow cast by grammar.
It is illuminating to juxtapose Wittgenstein's conception of grammar with his earlier conception of logical syntax. According to the Tractatus the surface grammars of ordinary languages may differ, but this conceals an underlying uniformity that is made manifest by logical analysis. Analysis will bring to view the essential rules of any possible language in virtue of which a symbolism can represent reality. Logical syntax is a system of rules for the use of signs. These rules are of various kinds. There are rules for the combination of propositions by means of truth-functional operators. Different kinds of rules, viz. definitions of names of complexes, introduce abbreviatory symbols. Yet other rules stipulate combinatorial possibilities for simple signs of various kinds.
The discussion of the metaphysical doctrines of the Tractatus would be incomplete without an examination of the oracular remarks in the 5.6's on solipsism and the self. These belong (in Kantian terms) to the ‘metaphysics of experience'. The fundamental contention of the section is that there is a sense in which solipsism is true, ‘what the solipsist means is quite correct; only it cannot be said, but makes itself manifest [es zeigt sich] (TLP, 5.62). In the sense in which solipsism is true, however, the expression of it coincides with pure realism (TLP, 5.64). The obscure argument supporting these claims rests upon two struts. First, it rests upon considerations of the relationship of language, the world, and the self; secondly, upon the analysis of the relations between the concepts of the knowing self, the empirical self, and the metaphysical self. The task of this chapter is to explore these relationships.
First, was Wittgenstein in any sense, a solipsist? If he was, then one must explain how a strictly thought-out solipsism coincides with realism. Secondly, the connections between any solipsistic views in the 5.6's and the rest of the Tractatus must be examined to see whether the putative solipsism follows from the account of language and meaning given in the book. These are the immediate purposes of the following discussion. One of the primary means to attain them will consist in a detailed comparison of some of Wittgenstein's doctrines with those of Schopenhauer from whom they are derived. This will not only throw light upon the Tractatus but will also serve a more long-term objective. This is to show that the detailed refutation of solipsism and of idealism, which Wittgenstein produced in the 1930s and incorporated, in low key, in the Investigations, is directed inter alia against views which he himself held as a young man. The Schopenhauerian influence upon Wittgenstein is most prominent in the Notebooks 1914-16, where his idealist and solipsist bent is most readily demonstrable. Thus even if the explanations I shall suggest of the Tractatus solipsism are incorrect, the latter purpose will be satisfactorily fulfilled if the explanations of the Schopenhauerian sections of the Notebooks are correct.
Wittgenstein's argument against the possibility of a private language is an endeavour to show that a certain conception of the mind, of self-consciousness or self-awareness, of knowledge of other minds and of perceptual experience, is deeply incoherent. The incoherence of this pervasive picture of the mind is co-ordinate with fundamental misconceptions about language, meaning, and understanding. These in turn strikingly exemplify the distorting force of the pre-theoretical assumption that the essential function of words is to name and of sentences to describe.
The private language argument is, if correct, one of the most important philosophical insights achieved in this century. It is a criticism of the conception of the mind which is not merely the dominant one in European philosophy, but is also pervasive in our culture, in psychology, linguistics, and indeed in the reflections of most people who think about the nature of ‘self-consciousness’ and the mind. For our reflective conception of our awareness of our own thoughts, desires, and emotions, our intentions, delights or perceptions is moulded by the picture of a contrast between what is ‘inner’ and what is ‘outer'. And we quite naturally construe what is ‘inner’ on the model of what is ‘outer'. We can, we think, inspect the objects in the world around us, or introspect the ‘objects’ of the ‘world’ within us. We take the latter on analogy with the former—and it is precisely there that we fall into confusions.
The consequent array of misconceptions of the mind presupposes a distinctive picture of language. For we are inclined to view the primitive indefinable terms of a language as deriving their meaning from our immediate experiences. Terms like ‘red’ or ‘sour', ‘pain’ or ‘joy', ‘thought’ or ‘desire’ are, we think, understood by anyone who has had the experience of seeing red or tasting a sour taste, suffering pain or being joyful, thinking or willing, and who has attached those words to the appropriate experiences. In this sense, the ‘foundations’ of language are conceived to lie in private experience. I know what I mean by ‘pain’ or by ‘red', one wants to say, I mean this f —and one, as it were, points within.
Philosophers hunt for the map of Treasure Island in order to find the treasure, and they do not realise that the treasure is the map!
– P. M. S. Hacker, Insight and Illusion, p. 149
I first got my undergraduate hands on Insight and Illusion in its 1997 Thoemmes Press reprint of the revised second edition, subtitled Themes in the Philosophy of Wittgenstein. While, at the time, I was a finalist at St Anne's College, Oxford, it was owing to sheer providence that I had been farmed out to Peter Hacker at St John's for my Philosophy of Mind tutorials. These sessions constituted not only my introduction to Wittgenstein, but also to the work of Elizabeth Anscombe, J. L. Austin, Arthur W. Collins, Anthony Kenny, Norman Malcolm, Gilbert Ryle, G. H. von Wright and A. R. White. Just as my degree (and, with it, also my interest in philosophy) was coming to an end, Peter opened up a whole new world to me. The door to that world was Wittgenstein's philosophy and the key to it was Insight and Illusion.
It is customary to say of books one adored as a student that they got one through college but, such was the hostility towards Wittgenstein's philosophy at the time within UK academia, that it would be closer to the truth to say that Insight and Illusion almost stood in the way of my degree. Undaunted, I returned to it several times over the years to explore philosophy until I arrived where I had begun, knowing the place for the first time.
Insight and Illusion was the first single-authored book to cover all phases of Wittgenstein's life and thought. The portable guide takes the reader through the major themes and concepts in Wittgenstein's works. In the name of exhaustiveness, these include the so-called picture theory of meaning; the say/show distinction; the principle of verification; antimetaphysics; anti-scientism; tautologies; the nature of mathematical propositions; ordinary language and nonsense; the law of the excluded middle; the Augustinian picture of language; knowledge and certainty; explanation and understanding; volition and the will; the relation of meaning to use; ostensive definition; ownership of experience; the first-person pronoun; the inner/outer; philosophical psychology; anti-solipsism; forms of life; the so-called private language argument; the autonomy of grammar; language games; and rule-following.
The philosophy expounded in the Tractatus seemed to Wittgenstein to contain at least the blueprint for the solution or dissolution of all the problems of philosophy. Between the completion of the work in 1918 and 1929, Wittgenstein abandoned philosophical research. His task subsequent to his return to philosophy in 1929 involved the pursuit of two general aims. The critical and destructive task concerned the dismantling of most of the Tractatus philosophy, and a detailed probing into the faults inherent in the Tractatus picture of language. The positive and constructive object was to rebuild an equally comprehensive set of answers to a similar array of philosophical problems. This chapter is concerned first with the disintegration of the Tractatus philosophy, and secondly with the general direction of the reconstruction in the 1930s.
With the qualifications implicit or explicit in the last two chapters, the Tractatus is a well-integrated philosophy. It is thus plausible to suppose that one could begin dismantling the structure from more than one point. For Wittgenstein himself, however, the weakness became exposed at what might appear a matter of detail, namely the mutual exclusion of determinates of a dcterminable. The colour-exclusion problem was introduced in the Tractatus, 6.3751 to exemplify the contention that all necessity is logical necessity. Appearances notwithstanding, the impossibility of the simultaneous presence of two colours at the same place is not a synthetic a priori truth, but a logical truth. The claim that ‘A is red and A is blue’ is contradictory (where ‘A’ refers to a point in the visual field at a given time) implies, in the Tractatus system, that the two conjuncts are not elementary propositions and that ‘red’ and ‘blue’ are not names of simples. For elementary propositions are logically independent, hence their conjunction cannot be contradictory. The programme implicit in 6.3751 was to show that when ‘A is red’ is fully analysed into its constituents, its truth will perspicuously entail that A is not blue, i f statements of degree were analysable—as I used to think', Wittgenstein explained later (RLF, pp. 168 f.) ‘we could explain this contradiction by saying that the colour R contains all degrees of R and none of B and that the colour B contains all degrees of B and none of R.'
To try to outline the limits of the knowable is one of the traditional tasks of epistemology. Some epistemological doctrines concerning the possibility of knowledge seem both intelligible and reasonable. Kant's demand that the employment of the categories be confined to the province of possible experience if knowledge is to be achieved might be taken as an example. But on further scrutiny, what is acceptable in Kant's account is a purely logical or grammatical point about the conditions of the intelligible employment of the categories, not an independent epistemological point about the limits of knowledge. And this grammatical point is one which Kant himself violated in his insistence that one may have beliefs about objects that transcend any possible experience. Other epistemological doctrines seem intelligible without being, by our ordinary canons, reasonable. Thus the various forms “of scepticism confine our possible knowledge within limits far more restrictive than we normally entertain. However, when the sceptics’ claims are put under pressure they are typically seen to violate an array of conceptual conditions for the correct employment of expressions which are utilized by sceptics in making their epistemological claims. Hence the latter are not, appearances to the contrary, genuinely intelligible. In both cases what seem to be epistemological theses collapse into grammatical insights or confusions.
As we have seen, Wittgenstein claimed that one cannot know that one is having a given experience. One cannot be said to know that one is in pain, that one is thinking a certain thought, or that one intends to act in a certain way. This seems to be an epistemological point, drawing the boundaries of possible knowledge in a manner that is prima facie bizarre. For, he insisted, other people can and often do know that someone else is suffering, is thinking such and such thoughts, or is intending to carry out certain projects. But what they can thus know, the sufferer, thinker, or intending agent cannot himself know. And this seems decidedly odd. To a philosopher familiar with the broad tradition of European philosophy, Wittgenstein seems to be setting his face against what is most obvious.