Ordinary language is all right.
One could divide humanity into two classes:
those who master a metaphor, and those who hold by a formula.
Those with a bent for both are too few, they do not comprise a class.
'[W]ir nämlich in der Philosophie den Gebrauch den Wörter oft mit Spielen, Kalkülen nach festen regeln, vergleichen, aber nicht sagen können, wer die Sprache gebraucht, müsse ein solches Spiel spielen…'
The claim about our relation to the use of words in philosophy is more or less unrestricted: it concerns our relation to (our own) language, especially that aspect of language which has been emphasized throughout the first eighty sections of the Investigations, its use.
The claim says that we (often) (1) compare the use of words with 'games, calculi with fixed rules', but (2) cannot say that someone who uses language must be playing such a game.
How is it that we 'cannot' say this? I gather that Wittgenstein means that we cannot establish it to our satisfaction, can't be sure of ourselves when saying that this is what we're doing: that what we're doing, when using words (i.e., according to the Wittgenstein of the Investigations, when talking), is subject to some sort of 'must'.
And if we could say this—what would we be saying? The claim is that in our comparisons between our uses of words and certain games—which I take to mean, roughly, the specific sorts or forms of the use of language of which Wittgenstein has been giving and imagining examples all along—the games, or, let's say, our descriptions of them, enjoy some kind of priority over our uses of words. That priority is registered in a form of description of what we're doing: what we must be doing is playing those games—as opposed to, I guess, just doing whatever it is we're doing, in using the relevant words in the relevant ways, and however it is that we describe that, or however it is to be described (perhaps even, at the limit, using terms just like those in which the games have been described, excepting the 'must'?).
At least, that's one reading. There's another, because Wittgenstein's phrasing is exactly ambiguous, thanks to the paratactical conjoining of 'games' with 'calculi with fixed rules'. Why not just take this as an elaboration of what he means here by 'games'? —Because it is clearly not what he means by 'games' earlier in the book; because he immediately recurs to the former term, and subsequently the the latter, and in ensuing remarks backs off to such an extent that even imputing to us (when we use language, or do anything at all) the playing of definite games according to any rules at all is called into question—in short, because he seems to want to talk about both ideas, distinctly but in relation to one another.
According to the second reading, Wittgenstein is saying much the same thing, but saying it about a distinct object of comparison. And that other thing to which we compare our uses of language, 'calculi with fixed rules', would appear to offer a way to understand the source of the 'must' we are unable to do more than insist upon: at the end of this section Wittgenstein refers to his former self as having mistakenly thought that 'if anyone utters a sentence and means or understands it, he is thereby operating a calculus according to definite rules', rules with a kind of ideal definiteness such that our own languages would seem to 'only approximate to such calculi'.
Why the ambiguity? Why does Wittgenstein want to talk about both of these ideas in such proximity, practically an entanglement, with each other? Because all along he has been using the analogy to games to prepare the way for a criticism of some attraction to calculi with fixed rules? Because he is thinking of these calculi as kinds of games, which we do play for certain purposes? (But then why not say we cannot say we play those, rather than that we cannot say we play particular games at all?)
—I think because he wants to use the idea of a (language-)game in criticism of that old—Tractatus—idea of using language being a matter of operating a calculus, while also making sure that this criticism is not wrongly taken to imply that thinking of language in terms of games, rather than in terms of (logical) calculi, solves the problems that the latter was meant to. In the manner that the latter was meant to. And mainly, the problem of skepticism, as taken up in the Tractatus.
Perhaps the structure of the Investigations indicates this double aim. §§81–88 are, to me, oddly placed. Although there is a language-game introduced in §86—one which recapitulates much of the development through the book of its model, the builders' game from §2, simply by virtue of being played with a table that serves as a kind of rule for obeying builder A's orders—it seems like nothing, or not enough, gets done in these sections. And it seems like there's a new intensity of interest in the idea of a rule, but before that interest is really pursued (fully from §142 on), we get the remarks on logic's sublimity in §§89–108, and the metaphilosophical remarks in §§109–133. This new interest is interrupted. However: the reference back to Wittgenstein's Tractatus mistakes in §81 is complemented by the direct consideration, in §134, of a tractarian idea, that 'es verhält sich so und so' expresses the general form of a proposition. And soon after, with reference to the same case, when Wittgenstein notes that 'we call something a proposition if in our language we apply the calculus of truth functions to it', he gives the clearest example of what he might have in mind when talking about 'calculi with fixed rules' (in a book where he almost never refers to 'calculi' anyway): truth-functional propositional logic, on which the anti-skeptical hopes of the Tractatus were made to hang. As if the reason that the 'criticism of the Tractatus', or its conception, that one finds in §§89–133 can seem so glancing, is just that there's so little to say directly about it once you have some distance from the thought that our everyday language harbors (must harbor) some ultimately truth-functional analysis of its meaningful (possibly true) statements about things if our making contact with the world in language is to be guaranteed. —Once using the propositional calculus looks like one thing we do, but you retain the idea that something like skepticism is to be addressed, (sort of) answered, on the level of 'us, our language, and the world', with all the things we do that that includes.
Besides this structural oddity, there's just the fact that doubt is not really broached, as an explicit topic of Wittgenstein's remarks, until §§81–88. As if the double aim legible here has to do with the differences between his old and new ways of addressing skepticism, but it was not until this stage in the Investigations that he was in a position to voice skepticism, as he was not, in a different way, ready to rule it out of bounds until quite late in the Tractatus—6.51, nearly the end.
So what is his new way of addressing skepticism? And why is it caught up with this double sense in which there is a 'must' that we cannot, to our satisfaction, say?
'But whatever we do we must do confidently (if we are timid, let us, then, act timidly), not expecting more light, but having light enough. If we confidently expect more, then let us wait for it. But what is this which we have? Have we not already waited? Is this the beginning of time? Is there a man who does not see clearly beyond, though only a hair's breadth beyond where he at any time stands?
If one hesitates in his path, let him not proceed. Let him respect his doubts, for doubts, too, may have some divinity in them. That we have but little faith is not sad, but that we have but little faithfulness. By faithfulness faith is earned. When, in the progress of a life, a man swerves, though only by an angle infinitely small, from his proper and allotted path (and this is never done quite unconsciously even at first; in fact, that was his broad and scarlet sin,—ah, he knew of it more than he can tell), then the drama of his life turns to tragedy, and makes haste to its fifth act. When once we thus fall behind ourselves, there is no accounting for the obstacles which rise up in our path, and no one is so wise as to advise, and no one so powerful as to aid us while we abide on that ground. Such are cursed with duties, and the neglect of their duties. For such the decalogue was made, and other far more voluminous and terrible codes.
These departures,—who have not made them?—for they are as faint as the parallax of a fixed star, and at the commencement we say they are nothing,—that is, they originate in a kind of sleep and forgetfulness of the soul when it is naught. A man cannot be too circumspect in order to keep in the straight road, and be sure that he sees all that he may at any time see, that so he may distinguish his true path.'
Someone who is dubious hesitates; what is dubious is not to be relied upon. What Thoreau counsels against are exactly forms of self-doubt which are opposites of Emerson's self-trust, a relation to self, a mode of conducting oneself, one's life, the description of which is apt to multiply possessive pronouns with every effort to distinguish the true from the false. Even doubts can be your own, or not, so this is a perspective on oneself from which some unheeded doubt may betray self-doubt—as may taking the wrong doubts too seriously: say, as if allaying them would even begin to allay one's own. As if it would even be to listen to one's own.
The very idea of a 'reason for doubt' has to be connected to something like doubt's dictionary definition: 'a feeling of uncertainty or lack of conviction'. Cartesian doubt is a disciplined doubt: it seeks to replace flickering conviction (and thus wavering or irresolute commitment) with only those doubts expressible as unexcluded or unexcludable possibilities in the entire space of possibilities (according to some form of expression associated with that space of possibilities, preferably one which is capable of fully articulating it). In that sense, it promises to spare us the trouble, even suffering, attendant upon the other kind of doubt—though instead of 'other kind' I should instead say something apt about the range of ways in which we doubt, the range of things we ordinarily call 'doubting', sometimes on the strength (or weakness) of a feeling, sometimes for clearly discernible or statable reasons, sometimes despite ourselves, for reasons unknown. But the contrast to felt doubt, feelings of uncertainty, shouldn't be taken to license a description of Cartesian 'reasons for doubt' as something like 'objective'. Within the frame constituted by the language he uses, the (ordinary, Wittgensteinian) grammar of that language which he implicitly consults, and the complement of traditional philosophical concepts he still takes over ('via the senses', etc.), Descartes is probably aiming for something like a universality of doubt: doubts which anyone can or ought to have (thus cannot or ought not rule out, yet), on reflection. But not for all that 'objective': for they are doubts which can be neither considered nor answered without a doubter, and without Descartes' particular script to follow. The meditator is trained to trade feeling for disciplined believing.
Again, during Wittgenstein's interpolated investigation of 'reading' (§157):
'Der Lehrer kann hier auch vom Abgerichteten nicht sagen: »Vielleicht hat er dieses Wort schon gelesen«. Denn es ist ja kein Zweifel über das, was er getan hat.'
—Doubting what's done is the least credible sort of doubt. Most impractical. But when a case has been contrived to turn exactly on what has or has not been done, then doubting what was just said to be the case amounts to not being able to see what's right in front of you—not being able to realize (imagine) what you're saying.
How is that falling from the sky?!
Problems become conventional. As the ways we live or act can.