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.
'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.
In the first chapter of Some Main Problems of Philosophy Moore says so many ridiculous things, which is all the more funny (frustrating) since he purports to be defending 'Common Sense' (and its 'most important views' about 'things which we all commonly assume to be true of the Universe, and which we are sure that we know to be true about it'). So, say, to kick the inventory off, he says:
'… we certainly believe that there are in the Universe enormous numbers of material objects, of one kind or another. We know, for instance, that there are upon the surface of the earth, besides our own bodies, the bodies of millions of other men; we know that there are the bodies of millions of other animals; millions of plants too; and besides all these, an even greater number of inanimate objects—mountains, and all the stones upon them, grains of sand, different sorts of minerals and soils, all the drops of water in rivers and in the sea, and moreover ever so many different objects manufactured by men; houses and chairs and tables and railway engines, etc., etc.'
As he continues, he starts to include more recently accepted items of belief, concerning the earth itself, its absurdly small size 'in comparison with the whole material Universe', the sun, the moon and 'all the immense numbers of visible stars' and their being situated at huge distances from us—apparently in part so that he can contrast the current state of Common Sense to a former one:
'All this we now believe about the material Universe: it is surely Common Sense to believe it all. But, as you know, there was a time when it was by no means Common Sense to believe some of these things: there was a time when nobody believed some of them. There was a time when there were not nearly so many men upon the earth as there are now; and when those who were upon it did not know how many there were. They believed only in the existence of a comparatively small number of human bodies beside their own; of a comparatively small number of animals and plants; and they had no idea how large the surface of the earth was. They believed, too, that the heavenly bodies were small compared to the earth, and at comparatively short distances from the earth. But I think I am right in saying we now believe that these primitive views about the material Universe were certainly wrong.'
—But a core of belief persists!
'… so far as concerns the point that there are in the Universe a great number of material objects, it has, so far as we know, remained the same. So far as we know, men have believed this almost as long as they have believed anything: they have always believed in the existence of a great many material objects.'
Even if, in context, Moore's intent is fairly clear—he wants to explain what he claims is 'the first and most important problem of philosophy', viz. 'To give a general description of the whole of the Universe', and the exhaustiveness of any such view is one of the criteria he most often emphasizes as making it count as philosophical, thus the show of scruples at counting all the little plants and all the little rocks and all the little drops of water in the sea—it's hard not to smile at how silly he can sound. We know that there are upon the surface of the earth millions of plants… although formerly, those who were upon the earth believed only in the existence of a comparatively small number of plants. In some sense, sure. But all it takes is a walk through a field to feel how stylized Moore's description is, how conventional in its choice of terms—the men, the animals, the plants, the rocks, the sea, the manufactures of men—let alone how foreign, in the sense familiar from Austin's criticisms of philosophers, to what the ordinary man ('man') 'believes' about the field, world, he walks through. (How many plants are there in it?? »Der Boden war ganz mit Pflanzen bedeckt«…)
Not that Moore doesn't recognize this. (See e.g. the first sentence of Chapter 15: 'Discussion of Chapter 14 shewed [!] that it was not quite clear to everyone in exactly what sense I was using the word “belief."') But that level of fidelity to ordinary language, to its embodiment (per Austin) of 'the inherited experience and acumen of many generations of men', is not exactly Moore's aim, if related to it. Moore intends, like he says, to discuss 'the main problems of philosophy'. And he proposes initially to do so through an overview giving 'a general idea of what philosophy is: or, in other words, what sort of questions it is that philosophers are constantly engaged in discussing and trying to answer' (p. 13). Once he fills out his picture of Common Sense's view of what there is in 'the whole of the Universe' (in summary, later: 'there certainly are in the Universe two very different kinds of things, namely material objects and acts of consciousness… conscious acts are attached to comparatively few among the material objects in the Universe… the vast majority of material objects are unconscious… the only bodies to which we should say we know them with certainty to be attached are the living bodies of men, and perhaps other animals, upon the Earth' [p. 23], '… material objects are all of such a kind that they may exist, even when we are not conscious of them, and… many do in fact so exist' [p. 24], and '[w]e believe that we really do know all these things' [p. 25]'), by virtue of what was included in it, Common Sense's view has been set up to contrast to the views of philosophers:
'… all of these beliefs taken together do not amount to a general description of the whole Universe: they are not a general description of the whole Universe, in the sense in which I said that the first problem of philosophy was to give us such a description. They consist in saying that there certainly are in the Universe certain large classes of things, and that these things are related to one another in certain ways. But what they do not say, as they stand, is that these large classes of things are the only classes of things which are in the Universe, or which we know to be in it: they do not say that everything which we know to be in the Universe belongs to one or other of these classes; they do not deny, as they stand, that there may be classes of things which do not belong to any of the classes I have mentioned. For instance, Common Sense says, according to me: There are in the Universe two classes of things: There are material objects in space, and there are the acts of consciousness of living men and animals upon the surface of the earth. But, in order to convert these statements into a general description of the whole Universe, we should have to add one or other of two things. We should have to say either: Everything in the Universe belongs to one or other of these two classes; everything is either a material object in space, or an act of consciousness of some man or animal on the earth. And this would plainly, if any one said it, profess to be a general description of the whole Universe. Or else we might say: Everything which we know to be in the Universe, does belong to one or other of these two classes; though there may be in the Universe other things, which we do not know to be in it. And this also, I think, might fairly be said to be an attempt to give a general description of the whole Universe. It would, indeed, consist in saying that, in a sense, no such description can be given' (pp. 27–8).
Then come the philosophers' views (pp. 28–37). Moore organizes them in terms of whether they 'add' something to or 'contradict' Common Sense's as yet not exhaustive description of the whole of the Universe, so as to obtain a genuinely philosophical description of it: views either (1) saying positively that there is more in the Universe than Common Sense is certain there is (so, interestingly, including the assertion of God's existence—which Moore treats as uncertain according to Common Sense—and the assertion of 'a future life', expressed in terms of the existence of 'acts of consciousness' not attached to living human bodies), or (2) skeptically (Moore's label) denying 'something Common Sense professes to know, without professing to know anything' (here, the examples are material-object skeptics who retain belief in 'acts of consciousness', which sound more or less like external-world skeptics on Moore's description, and other-minds skeptics, whom Moore immediately requires to be solipsists, on pain of illogically holding that none of the others among whom they exist, and to whom they assert their view, can know of the existence any others' minds); or (3) both 'adding' and 'contradicting' (here, the examples are evidently much more contentious—Berkeley and then a distinct family of examples not associated with any named philosophers, but apparently having something to do with Kant, Hegel, or Bradley, three philosophers who are the subjects of sustained and critical discussion later on—with a suddenly much trickier ascription of claims about the 'added' existences of 'Appearances' doing untold work to cordon this group of 'startling' views off from the others deemed not unfamiliar nor uncommon despite exceeding the beliefs of Common Sense—indicating the remote presence of some fratricidal academic campaigning in this book which otherwise affects such naiveté).
Thus 'the first and most interesting problem in philosophy' (p. 37), one 'plainly… peculiar to philosophy' (p. 14): to give a general description of the whole Universe. Moore doesn't say explicitly what makes it a problem, as opposed to, say, a question. He refers to both problems and questions as something philosophers concern themselves with—perhaps interchangeably so. But I think his fairly rigid scheme for setting out some answers to it suggests a natural distinction between questions and problems that helps to explain why he might have supposed that a discussion of philosophers' treatments of their problems was a fair enough way to give his readers an idea of what philosophy is; that is, why explain 'philosophy' by explaining 'philosophical problems'.
His late return to the idea of a philosophical problem, after the extensive examples, also introduces conditions on any solution to a problem (in particular, to that of giving a general description of the whole Universe):
'Any answer to the problem must consist in saying one or other of three things: it must say either that certain large classes of things are the only kinds of things in the Universe, i.e., that everything in it belongs to one or other of them; or else it must say that everything in the Universe is of one kind; or else it must say that everything which we know to be in the Universe belongs to some one of several classes or to some one class. And it must also, if it holds that there are several different classes of things, say something about the relation of these classes to one another' (p. 37).
'Must'. Where did that come in? Evidently from the same place as 'only': from the acceptance of the ambition to describe the whole Universe, to aim at a 'universe' at all, at all of existence, everything there is. And jointly from the core mass of beliefs of Common Sense as to what there is, which not only seem to leave some space to fill, but also already contain distinctions—natural ones? necessary ones?—that divide a seemingly considerable portion of 'everything' into classes fit for framing some noticeably combinatorial possibilities. The material objects, the minds (and their acts of consciousness), other possible things, or no other possible things, or perhaps even less than the material objects and the minds, in their duality, initially led us to assume: all these set up as alternative ways of saying exhaustively what there is. 'Must' enters because as a problem, the question of what there is has been framed in terms of givens which delimit a solution-space relative to the whole (which determines a furthest limit, a scope).
But only from there? What about that ambition to describe the whole universe? Without the 'everything' the little feat of logic that turns the possible classes of things taken from Common Sense into a basis-set of ontological categories would look more like game-playing. And in Moore's presentation the whole is given priority: he even seems to allow that opinions as to what there is in the whole of the universe count as philosophical (as above, in contrast to the more limited views of Common Sense) even if unproved, undefended, unargued: for 'philosophers have not been content simply to express their opinions as to what there is or is not in the Universe… They have also tried to prove their opinions to be true' (p. 37). Presumably there would be room here for the traditional ways of distinguishing philosophical outlooks on existence, say, from the (depending on who you ask) full-fledged performances of philosophers looking to justify their views or inquire into new ones.
I said before how stylized, how conventional, Moore's inventory of Common Sense seemed to me. And evidently his entire way of presenting 'giving a general description of the whole of the Universe' as a problem, and of framing alternative solutions to it as related to the core of Common Sense, trades heavily on conventional, traditional philosophical distinctions (the next chapter, for example, is called 'Sense-Data': a traditional distinction renewed and renamed by Moore and I don't know which others and sent forth to harden into later tradition). But I've been trying to draw out what his interest is in treating this 'problem' as a problem because I was struck by another highly conventional, traditional aspect of philosophy present in Moore's initial approach.
The tail end of Moore's first chapter touches on the role of knowledge in certain philosophical views emphasizing it which belong among the other answers to the problem of describing the whole universe; whenever knowledge shows up it appears as if Moore might be trying to brush past some complications. Sure enough, once he has slotted views concerning his 'first and most interesting problem' in with some subordinate problems (say, of definition, of what is meant by the different classes of things, of what the differences between them consist in) as belonging to the department of Metaphysics, there are some intermediate passages discussing philosophy's interest in questions like 'How do you know?', and then some more passages pertaining to knowledge (specifically, to what knowledge is, to truth, and to proof), which Moore assigns in a very traditional way to 'Logic' (rather than, say, the more modern epistemology or the more current 'theory of knowledge'), and then some quick words on 'Ethics'.
This is pretty much Pierre Hadot's constantly-invoked trio of physics, logic, and ethics.
'Moore said "I know that there's a tree," partly because of the feeling that if it turned out not to be a tree, he would have to "give up."'