What is meant by "rational"?

What is the use of designating some formations of opinion as rational, while others (perhaps leading to the same results) are stigmatized as rules of thumb, or of authority, or as mere guesses? When we reason we set out from an assumed representation of a state of things. This we call our "premiss"; and working upon this, we produce another representation which professes to refer to the same state of things; and this we call our "conclusion". But so we do when we go irreflectively by a rule of thumb, as when we apply a rule of arithmetic the reason of which we have never been taught. The irrationality here consists in our following a fixed method, of the correctness of which the … method [itself] affords no assurance; so that if it does not happen to be right in its application to the case in hand, we go hopelessly astray. In genuine reasoning, we are not wedded to our method. We deliberately approve it, but we stand ever ready and disposed to reexamine it and to improve upon it, and to criticize our criticism of it, without cessation. Thus the utility of the word "reasoning" lies in its helping us to discriminate between the self-critical and uncritical formations of representations. If a machine works according to a fixed principle involved in the plan of it, it may be a useful aid in reasoning; but unless it is so contrived that, were there any defect in it, it would improve itself in that respect, then although it could correctly work out every possible conclusion from premisses, the machine itself would afford no assurance that its conclusion would be correct. Such assurance could only come from our critical examination of it. Consequently, it would not be, strictly speaking, a reasoning machine.

Unimportance of vitally important matters

Among vitally important truths there is one which I verily believe –- and which men of infinitely deeper insight than mine have believed –- to be solely supremely important. It is that vitally important facts are of all truths the veriest trifles. . . . To pursue "topics of vital importance" as the first and best [occupation] can lead only to one or other of two terminations -– either on the one hand what is called, I hope not justly, Americanism, the worship of business, the life in which the fertilizing stream of genial sentiment dries up or shrinks to a rill of comic tit-bits, or else on the other hand, to monasticism, sleepwalking in this world with no eye or heart except for the other.

Changes in his views across the years?

Although Peirce is much given to raising doubts about his own philosophy, yet the alterations it has undergone since 1866, except for the introduction of the problematical tychism and a few minor corrections (of which the most important relate to the precise nature, definitions, and grounds of validity of induction and abduction,) and an increasing insistence on the exclusion of psychological premisses from logic consist in the extension of his inquiries to new problems and the greater fullness of his positions.

Where Hegel went wrong

[Hegel's] system, not in its deeper and truer spirit, but as it is worked out, and notwithstanding a sop tossed in one of the closing sections, is anti-evolutionary, anti-progressive, because it represents thought as attaining perfect fulfillment. There is no conceivable fulfillment of any rational life except progress towards further fulfillment.

How to fix meanings

By his system of nomenclature, Sir William Hamilton has conferred an immense boon not alone on his own school but on all English philosophers who believe in anchoring words to fixed meanings. I deeply regret that I am not one of these. That is the best way to be stationary, no doubt. But, nevetheless, I believe in mooring our words by certain applications and letting them change their meaning as our conceptions of the things to which we have applied them progresses.

What is meant by "in the mind"?

The realist will hold that the very same objects which are immediately present in our minds in experience really exist just as they are experienced out of the mind; that is, he will maintain a doctrine of immediate perception. He will not, therefore, sunder existence out of the mind and being in the mind as two wholly improportionable modes. When a thing is in such a relation to the individual mind that that mind cognizes it, it is in the mind; and its being so in the mind will not in the least diminish its external existence. For he does not think of the mind as a receptacle, which if a thing is in, it ceases to be out of. To make a distinction between the true conception of a thing and the thing itself is, he will say, only to regard one and the same thing from two different points of view; for the immediate object of thought in a true judgment is the reality.

The logician and the real

Whether or not there is, at all, any such thing as Reality, the logician need not decide. He cannot hide from himself, any more than another man can, that objects very nearly like real things there are; and he cannot pretend to doubt it. But he sees, perhaps more clearly than other men, that approximation to reality and absolute reality itself are two different things. The mathematicians' i, of which the square is negative unity, approximates to reality. All that it is incumbent upon the logician to learn is what inferential habits are conducive to knowledge, and to positive knowledge, in case there be any reality of which it is possible to have positive knowledge, and are conducive to such semblance of positive knowledge as we can have, in case there is no perfect reality or in case otherwise true positive knowledge is impossible.

Thoughts are in signs, not in heads

The psychologists undertake to locate various mental powers in the brain; and above all consider it as quite certain that the faculty of language resides in a certain lobe; but I believe it comes decidedly nearer the truth (though not really true) that language resides in the tongue. In my opinion, it is much more true that the thoughts of a living writer are in any printed copy of his book than that they are in his brain.

There are no pure signs

No sign perhaps, can perfectly realize any one of these types [namely, icon, index, symbol]. They are like chemical elements, which the very laws of chemical reaction prohibit us from obtaining in absolute purity, but to the purification of which we can so far approximate as to get tolerably accurate ideas of their nature, and which present themselves habitually in such a degree of purity, that we have no hesitation in saying, This is gold, that silver, and the other copper; or this is iron, that nickel, and the third cobalt; although all are strictly mixtures of the three.

Logic is for the sake of reasonableness

"Logic came about for the sake of reasonableness, not reasonableness for the sake of logic." Let us never lose sight of that truth, forgotten though it is, every day, in every walk of life, especially in well-regulated America!

Knowledge is essentially social

No general description of the mode of advance of human knowledge can be just which leaves out of account the social aspect of knowledge. That is of its very essence. What a thing society is! The workingman, with his trade union, knows that. Men and women moving in polite society understand it, still better. But Bohemians, like me, whose work is done in solitude, are apt to forget that not only is a man as a whole little better than a brute in solitude, but also that everything that bears any important meaning to him must receive its interpretation from social considerations.