The difficulty in philosophy is to say no more than we know.

Here, as usually in philosophy, the first difficulty is to see that the problem is difficult. If you say to a person untrained in philosophy, "How do you know I have two eyes?" he or she will reply, "What a silly question! I can see you have." It is not to be supposed that, when our inquiry is finished, we shall have arrived at anything radically different from this unphilosophical position. What will have happened will be that we shall have come to see a complicated structure where we thought everything was simple, that we shall have become aware of the penumbra of uncertainty surrounding the situations which inspire no doubt, that we shall find doubt more frequently justified than we supposed, and that even the most plausible premisses will have shown themselves capable of yielding unplausible conclusions. The net result is to substitute articulate hesitation for inarticulate certainty.

[Philosophy] must set limits to what can be thought; and, in doing so, to what cannot be thought. It must set limits to what cannot be thought by working outwards through what can be thought.

The positivists have a simple solution: the world must be divided into that which we can say clearly and the rest, which we had better pass over in silence. But can anyone conceive of a more pointless philosophy, seeing that what we can say clearly amounts to next to nothing? If we omitted all that is unclear, we would probably be left completely uninteresting and trivial tautologies.

Philosophy, though unable to tell us with certainty what is the true answer to the doubts which it raises, is able to suggest many possiblities which enlarge our thoughts and free them from the tyranny of custom. Thus, while diminishing our feeling of certainty as to what things are, it greatly increases our knowledge as to what the may be; it removes the somewhat arrogant dogmatism of those who have never travelled into the region of liberating doubt, and it keeps alive our sense of wonder by showing familar things in an unfamilar aspect

The question whether we have not some knowledge independent of any and all experience — whether there must not, unavoidably, be some knowledge a priori, some knowledge which we come at simply by virtue of our nature — is really the paramount question, around which the whole conflict in philosophy concentrates, and on the decision of which the settlement of every other question hangs. To cast the career of a philosophy upon a negative answer to it, as if this were a matter of course, — which the English school from Hobbes onward has continually done, — is to proceed not only upon a petitio, but upon a delusion regarding the security of the road.

...philosophy does not, like exact or empirical science, bring us to know things of which we were simply ignorant, but brings us to know in a different way things which we already knew in some way; and indeed it follows from our own hypothesis; for if the species of a philosophical genus overlap, the distinction between the known and the unknown, which in a non-philosophical subject-matter involves a difference be-tween two mutually exclusive classes of truths, in a philosophical subject-matter im- plies that we may both know and not know the same thing; a paradox which disappears in the light of the notion of a scale of forms of knowledge, where coming to know means coming to know in a different and better way.

Perhaps then we shall stop pretending that we know everything, and shall be less bold in raising questions and getting
into confusing disputes with others about things to which
our understandings are not suited — things of which we can’t
form any clear or distinct perceptions in our minds, or, as
happens all too often, things of which we have no notions at
all. If we can find out what the scope of the understanding
is, how far it is able to achieve certainty, and in what cases
it can only judge and guess, that may teach us to accept our
limitations and to rest content with knowing only what our
human condition enables us to know.

Science is what you know, philosophy is what you don't know

A philosopher worthy of the name has never said more than a single thing: and even then it is something he has tried to say, rather than actually said. And he has said only one thing because he has seen only one point: and at that it was not so much a vision as a contact: this contact has furnished an impulse, this impulse a movement, and if this movement, which is as it were a kind of swirling of dust taking a particular form, becomes visible to our eyes only through what it has collected along its way, it is no less true that other bits of dust might as well have been raised and that it would still have been the same whirlwind. Thus a thought which brings something new into the world is of course obliged to manifest itself through the ready-made ideas it comes across and draws into its movement; it seems thus, as it were, relative to the epoch in which the philosopher lived; but that is frequently merely an appearance. The philosopher might have come several centuries earlier; he would have had to deal with another philosophy and another science; he would have given himself other problems; he would have expressed himself by other formulas; not one chapter perhaps of the books he wrote would have been what it is; and nevertheless he would have said the same thing.

A philosopher worthy of the name has never said more than a single thing: and even then it is something he has tried to say, rather than actually said. And he has said only one thing because he has seen only one point: and at that it was not so much a vision as a contact...

But even if all agreed together, it would not be enough to have their teachings. For we shall never be mathematicians, say, even if we retain in memory all the proofs others have given, unless we ourselves have the mental aptitude of solving any given problem; we shall never be philosophers, if we have read all the arguments of Plato and Aristotle but cannot form a solid judgment on matters set before us; this sort of learning would appear historical rather than scientific. Further, this Rule counsels us against ever mixing up any conjectures with our judgments as to the truth of things. It is of no small importance to observe this; for the chief reason why in the common philosophy there is nothing to be found whose certitude is so apparent as to be beyond controversy is that those who practice it have not begun by contenting themselves with the recognition of what is clear and certain, but have ventured on the further assertion of what was obscure and unknown and was arrived at only through probable conjectures. These assertions they have later on themselves gradually come to hold with complete confidence, and have mixed them up indiscriminately with evident truths; and the final result was their inability to draw any conclusion that did not seem to depend on some such proposition, and consequently to draw any that was not uncertain.

I am not trying here to define Philosophy, but, on the contrary, to strip it of any fixed definition, to leave it as free as possible to find its own definitions that are more fitting, provisional, celebrated or unaccepted. Just as I want to see it free of any "critical," "theoretical," or "profound" obligation, I would like to be able to experience it without the stigma of the edifying affirmativism that has haunted it throughout arduous times, as a struggle against rhetoric, relativism, skepticism, pessimism, and nihilism. I believe that philosophy has no duty to seek conceptual edification, salvation through ideas, or the construction of a just society. The less "tasks" it has, the better. I do not rule out the possibility that sophistry, rhetoric, relativism, skepticism, pessimism, or nihilism are powerful ways of thinking. It is not my task as a philosopher to "overcome skepticism," "overcome relativism," "go beyond nihilism," or "not be overwhelmed by pessimism," but to ponder whether skepticism, relativism, nihilism, or pessimism can develop as legitimate possibilities of thought. If skepticism is correct, we should be skeptical. If relativism sees important aspects of the real, we should be relativists. If our thinking leads us to see the world as nothing, we should be nihilists and pessimists. A philosopher has no apostolates or missions, and no obligation to engage in crusades. I have, therefore, no affirmative conception of philosophizing. Philosophical activity is, for me, ruthless, incisive and unforgiving, and goes as far as its categories lead it. A Philosophy may shake the values that sustain our society, or it may even destroy its own upholder. It is a dangerous task, whose outcomes cannot be predicted.

Philosophy can take us no further than enabling us to command a clear view of the concepts by means of which we think about the world, and, by so doing, to attain a firmer grasp of the way we represent the world in our thought. It is for this reason and in this sense that philosophy is about the world.