Wittgenstein’s Philosophical Methods in On Certainty
Wittgenstein’s Philosophical Methods in On Certainty


On Certainty has recently been characterized as marking a shift from the therapeutic tendencies of the Philosophical Investigations to a more systematic philosophical approach. While Wittgenstein sometimes engages in theoretical tasks in the earlier sections of On Certainty, I argue that he abandons this approach for a return to his familiar therapeutic and deflationary methods in the second half of the book. Wittgenstein praised his final efforts in On Certainty but repeatedly criticized his work found in the earlier sections. These shifts in methodology and self-critique are shown to correlate with changes in the cancer treatments that Wittgenstein received.

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    While a significant number of commentators have described the late Wittgenstein’s overall philosophical objectives as therapeutic or anti-theoretical, recent proponents of the ‘third Wittgenstein’ movement have argued that Wittgenstein changed his approach to philosophy in his final years, particularly in the notes published as On Certainty. Frongia and McGuinness have suggested that in On Certainty there is “a pronounced change in Wittgenstein’s attitude towards constructive and systematic ways of doing philosophy. Certainly there seems to be a loss of interest in the ‘therapeutic’ aim of removing ‘mental cramps’” (1990, 35). Moyal-Sharrock endorses such a reading, claiming that “Wittgenstein…somehow lost interest in the therapeutic enterprise in his last years…Wittgenstein’s third phase is characterized by a more accessible, readable style, and this stylistic change goes hand in hand with a change in method” (2004, 5).

    Although Wittgenstein is sometimes engaged in theoretical tasks in the earlier sections of On Certainty, I argue that he ultimately reverts back to his therapeutic and deflationary impulses in the second half of the work, and that he favored this later material over the earlier sections. The reasons for Wittgenstein’s shift in approach around the middle of On Certainty become clearer from a biographical investigation into the conditions in which On Certainty was composed.

    After discussions with Normal Malcolm at Cornell University during a visit in 1949, Wittgenstein wrote a series of remarks concerning Moore’s claim to know that “here is a hand.” These notes now form Part I of On Certainty, consisting of sections 1-65. For the next year and a half, up until his death, Wittgenstein composed remarks on a variety of topics, including certainty, color concepts, psychological terms, and Moore’s arguments. However, throughout most of this time he consistently complained that his work was of poor quality. Only in his final two months was he able to produce work that he could find satisfactory. This long decline and short ascent of Wittgenstein’s attitude towards his writing correlates with the medical treatments he received for prostate cancer, a condition that kept him in a physically weak and mentally dull condition until just before his death.

    After being diagnosed with prostate cancer in late 1949, Wittgenstein was quickly prescribed hormone and X-ray therapies. These occasionally lessened the symptoms, but also had side effects themselves, including depression and clouded cognition. In Wittgenstein’s many letters to Malcolm during the last years of his life, he claimed that his mind was dead and that he could no longer do any good work. In January 1950, soon after beginning treatment, he complained:

    [I am] pretty slow & stupid; I’ve only got very few lucid moments. I’m not writing at all because my thoughts never sufficiently crystallize. (1.16.50) (Malcolm 1984)

    Wittgenstein set aside the notes on Moore, and in the spring of 1950 completed a notebook of remarks concerning color and psychology. A week later he expressed dissatisfaction with the work he had produced:

    I have not been able to do any sustained good work since the beginning of March 1949…it seems to me likely that my mind will never again work as vigorously as it did, say, 14 months ago. (4.17.50)

    In late summer 1950 Wittgenstein attempted to revisit the topic of Moore and certainty once again. Part II (sections 66-192) and Part III (sections 193-299) of On Certainty were penned at this time. In late July, around the time he began writing Part II, he held his philosophical abilities in low esteem:

    I’m working but not particularly well. I get tired soon…I have hardly any philosophical discussions…I’ve got all sorts of unclear thoughts in my old head which will perhaps remain there for ever in this unsatisfactory state. (7.30.50)

    And in December 1950, two months after completing Part III, he did not appear to be satisfied with his prior effort:

    …it’s possible that I’m no longer able to do any decent research…My health is not too bad but I am very dull & stupid indeed. (12.1.50)

    A month later Wittgenstein was nearly resigned to the thought that he would never again be able to do any good work:

    …in my present state of health & intellectual dullness…[it is] against all probability & hope, [that] I should one day find that I could again do worthwhile work in philosophy…My mind’s completely dead. (1.12.51)

    Wittgenstein’s condition continued to decline, and he put aside the notes on Moore for another six months.

    Aware that the end of his life was soon approaching, Wittgenstein moved into the home of his doctor in Cambridge in February 1951. The cancer treatments were quickly terminated, and Wittgenstein began to finally achieve clarity in his thoughts soon afterwards. Between March 10th and April 27th, Part IV (sections 300-676) was composed.

    Wittgenstein communicated the good news about his change in health to Norman Malcolm on April 16th:

    An extraordinary thing has happened to me. About a month ago I suddenly found myself in the right frame of mind for doing philosophy. I had been absolutely certain that I’d never again be able to do it. It’s the first time after more than 2 years that the curtain in my brain has gone up. Of course, so far I’ve only worked for about 5 weeks & it may be all over by tomorrow, but it bucks me up a lot now. (4.16.51)

    This was his final letter to Malcolm. Wittgenstein died two weeks later on April 29th, 1951.

    These selections from Wittgenstein’s correspondence show that while he was generally dissatisfied with Parts 1-3 of On Certainty, he considered Part 4 some of his best work in years. This change in Wittgenstein’s perception of his work should prompt us to consider what features Part 4 has that Parts 1-3 lack, and why Wittgenstein valued these features so much. We find a clue in the note above, where Wittgenstein says that he is now finally able to approach philosophy “in the right frame of mind.”

    I suggest that one distinguishing feature between Part 4 and Parts 1-3 of On Certainty is a shift in method. In the early parts, Wittgenstein often appears to be engaged in straightforward theory building, responding to Moore and the skeptic with a general theory of language games. In these sections Wittgenstein less frequently uses his signature philosophical devices, such as imaging quite different uses of language than our own, leaving rhetorical questions unanswered, examining the multiple uses of certain propositions, or placing multiple voices in dialogue. Instead, these sections often appear to contain assertions and arguments. However, in Part 4 Wittgenstein seems to shift back to a therapeutic approach, once again utilizing his dialectical tools associated with the Philosophical Investigations. Thus, Wittgenstein achieved the “right frame of mind” in Part 4 by returning to the therapeutic methodology previously espoused in the second phase of his career.

    One example of this shift in approach can be found in a comparison between the way Wittgenstein reacts to Moore’s knowledge claims in Parts 1-3 and Part 4. The early parts appear to contain an attempt to deal with Moore (and the skeptic) by providing a theory of language games. In Part 2 Wittgenstein says that his project is meant to show that Moore’s knowledge-claims are in fact nonsense:

    Naturally, my aim must be to say what statements one would like to make here, but cannot make meaningfully [sinnvoll].(OC 76)

    The project Wittgenstein describes thus seems to be theoretical in nature; it involves delimiting a certain class of propositions and determining their semantic status. Towards this end, Wittgenstein introduces the idea of ‘hinge’ propositions, which we do not doubt in our investigations:

    It may be for example that all enquiry on our part is set so as to exempt certain propositions from doubt, if they are ever formulated. They lie apart from the route travelled by enquiry.(OC 88)

    The collection of our hinge propositions forms a world picture that constitutes the ground of judgment:

    But I did not get my picture of the world by satisfying myself of its correctness; nor do I have it because I am satisfied of its correctness. No: it is the inherited background against which I distinguish between true and false.(OC 94)

    Moore’s problem is then diagnosed as claiming to know certain hinge propositions, which – because they constitute the framework in which knowledge claims can be made – cannot themselves be the subjects of knowledge claims:

    When Moore says he knows such and such, he is really enumerating a lot of empirical propositions which we affirm without special testing; propositions, that is, which have a peculiar logical role in the system of our empirical propositions.(OC 136)

    This analysis also then applies to the skeptic, who attempts to doubt hinge propositions which themselves form the conditions that make doubting possible.

    Wittgenstein again revisits the unusual sorts of knowledge claims that Moore tends to make in Part 4, but this time his disposition seems to have changed. Instead of characterizing the type of propositions Moore utters by constructing a theory of sensible knowledge claims, Wittgenstein simply asks Moore to further clarify what exactly he is talking about. His conversational and dialectical tone here is more fitting for the therapeutic treatment of a philosopher than the solution of a philosophical problem.

    In Part 4, rather than dealing with an entire class of propositions Moore wants to assert, Wittgenstein especially focuses on one particular claim - “I know that that’s a tree.” Wittgenstein’s initial response to Moore’s claim is confusion; he isn’t sure if he understands what Moore is trying to say:

    "I know that that's a tree." Why does it strike me as if I did not understand the sentence? though it is after all an extremely simple sentence of the most ordinary kind? It is as if I could not focus my mind on any meaning.(OC 347)

    He is puzzled in part because the claim seems so unmotivated; he is not sure of the point of the utterance:

    If someone says, "I know that that's a tree" I may answer: "Yes, that is a sentence. An English sentence. And what is it supposed to be doing?"(OC 352)

    Wittgenstein invites Moore to make his claim more understandable by describing the way he is trying to use the proposition. In Part 4 Moore’s claim is not declared nonsense at the outset. For all Wittgenstein knows, Moore may successfully clarify what he is trying to say and end up making sense.

    Wittgenstein attempts to show Moore examples of how an unclear statement could be given a more determinate meaning. He imagines several different circumstances in which, when claiming to know that something is a tree, the meaning and purpose of this statement would be understood:

    "I know that that's a tree"--this may mean all sorts of things: I look at a plant that I take for a young beech and that someone else thinks is a black-currant. He says "that is a shrub"; I say it is a tree.--We see something in the mist which one of us takes for a man, and the other says "I know that that's a tree". Someone wants to test my eyes etc.(OC 349)

    By providing these examples, Wittgenstein is implicitly encouraging Moore to continue in the same way and to flesh out the context of his own utterance. Moore is not being set to an impossible task, for Wittgenstein shows that he is certainly capable of being convinced by a reasonable explanation of the point behind an initially unclear utterance:

    In the middle of a conversation, someone says to me out of the blue: "I wish you luck." I am astonished; but later I realize that these words connect up with his thoughts about me. And now they do not strike me as meaningless any more.(OC 469)

    If Moore can provide such an explanation, then he will give his utterance a clear meaning and resolve Wittgenstein’s confusion.

    Wittgenstein hopes that Moore will notice that the meaning of his unusual utterances tend to get clear only once they are taken out of a philosophical context and given an everyday use:

    It is queer: if I say, without any special occasion, "I know"--for example, "I know that I am now sitting in a chair", this statement seems to me unjustified and presumptuous. But if I make the same statement where there is some need for it, then, although I am not a jot more certain of its truth, it seems to me to be perfectly justified and everyday.(OC 553)

    As soon as I think of an everyday use of the sentence instead of a philosophical one, its meaning becomes clear and ordinary.(OC 347)

    Of course, Moore is not attempting to give the phrase “I know this is a tree” an everyday use; he is trying to generate substantive philosophical conclusions from this proposition. Yet every successful attempt Moore might make at explaining himself, i.e., making his utterance “clear” and “justified” by explicating its context and use, ends up resulting in an “ordinary” and “everyday” sentence that lacks the philosophical punch he is seeking.

    Wittgenstein intends for his interaction with Moore to have a therapeutic result. After constantly being frustrated by his attempts to clarify the sense of his claim, “I know that that’s a tree,” because all such attempts end up missing what he ‘really means,’ it is hoped that at some point Moore will come to question whether even he actually knows what he is trying to get across with this phrase, or whether it is doing any work at all. In the wake of this it is hoped that Moore will let go of his desire to make this claim in the first place. So, rather than instructing Moore to no longer claim that he knows that this is a tree because of the status of that statement in some theory of meaningful utterances, Wittgenstein’s goal in Part 4 of On Certainty is much more deflationary. He hopes that their interaction will help Moore adopt a perspective in which he simply has no desire to make such a claim.


    1. Frongia, Guido and McGuinness, Brian F. 1990 Wittgenstein: a Bibliographical Guide, Oxford: Blackwell.
    2. Malcolm, Norman 1984 Ludwig Wittgenstein: a Memoir, 2nd edn, Oxford: OUP.
    3. Moyal-Sharrock, Danièle (ed.) 2004 The Third Wittgenstein: The Post-InvestigationsWorks, Burlington, VT: Ashgate.
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