Quoted in Hawes The Logic of Contemporary English Realism (1923), p. 110;Most people would die sooner than think – in fact they do so. cf. Ockham's maxim: entia non sunt multiplicanda praeter necessitatem.
1920s

“The principal source of the harm done by the State is the fact that power is its chief end.”

Bertrand Russell

Principles of Social Reconstruction (1917), Ch. II: The State
1910s

“My own opinion—which I may as well indicate at the outset—is that pure Anarchism, though it should be the ultimate ideal, to which society should continually approximate, is for the present impossible, and would not survive more than a year or two at most if it were adopted. On the other hand, both Marxian Socialism and Syndicalism, in spite of many drawbacks, seem to me calculated to give rise to a happier and better world than that in which we live. I do not, however, regard either of them as the best practicable system. Marxian Socialism, I fear, would give far too much power to the State, while Syndicalism, which aims at abolishing the State, would, I believe, find itself forced to reconstruct a central authority in order to put an end to the rivalries of different groups of producers. The best practicable system, to my mind, is that of Guild Socialism, which concedes what is valid both in the claims of the State Socialists and in the Syndicalist fear of the State, by adopting a system of federalism among trades for reasons similar to those which are recommending federalism among nations.”

Bertrand Russell

Introduction, p. 6
1910s, Proposed Roads To Freedom (1918)

“So much of modern mathematical work is obviously on the border-line of logic, so much of modern logic is symbolic and formal, that the very close relationship of logic and mathematics has become obvious to every instructed student. The proof of their identity is, of course, a matter of detail: starting with premisses which would be universally admitted to belong to logic, and arriving by deduction at results which as obviously belong to mathematics, we find that there is no point at which a sharp line can be drawn, with logic to the left and mathematics to the right. If there are still those who do not admit the identity of logic and mathematics, we may challenge them to indicate at what point, in the successive definitions and deductions of Principia Mathematica, they consider that logic ends and mathematics begins. It will then be obvious that any answer must be quite arbitrary.”

Bertrand Russell

Source: 1910s, Introduction to Mathematical Philosophy (1919), Ch. 18: Mathematics and Logic

“Freedom comes only to those who no longer ask of life that it shall yield them any of those personal goods that are subject to the mutations of time.”

Bertrand Russell

1900s, A Free Man's Worship (1903)

“At puberty, the elements of an unsuperstitious sexual morality ought to be taught. Boys and girls should be taught that nothing can justify sexual intercourse unless there is mutual inclination… Boys and girls should be taught respect for each other's liberty; they should be made to feel that nothing gives one human being rights over another, and that jealousy and possessiveness kill love. They should be taught that to bring another human being into the world is a very serious matter, only to be undertaken when the child will have a reasonable prospect of health, good surroundings, and parental care. But they should also be taught methods of birth control, so as to insure that children shall only come when they are wanted. Finally, they should be taught the dangers of venereal disease, and the methods of prevention and cure. The increase of human happiness to be expected from sex education on these lines is immeasurable.”

Bertrand Russell

1920s, What I Believe (1925)

“Power may be defined as the production of intended effects.”

Bertrand Russell

Source: 1930s, Power: A New Social Analysis (1938), Ch. 3: The Forms of Power

“An atheist, like a Christian, holds that we can know whether or not there is a God. The Christian holds that we can know there is a God; the atheist, that we can know there is not. The Agnostic suspends judgment, saying that there are not sufficient grounds either for affirmation or for denial. At the same time, an Agnostic may hold that the existence of God, though not impossible, is very improbable; he may even hold it so improbable that it is not worth considering in practice. In that case, he is not far removed from atheism. His attitude may be that which a careful philosopher would have towards the gods of ancient Greece. If I were asked to prove that Zeus and Poseidon and Hera and the rest of the Olympians do not exist, I should be at a loss to find conclusive arguments. An Agnostic may think the Christian God as improbable as the Olympians; in that case, he is, for practical purposes, at one with the atheists.”

Bertrand Russell

What is an Agnostic? (1953)
1950s

“[Unlike the] utilitarian… I judge pleasure and pain to be of small importance compared to knowledge, the appreciation and contemplation of beauty, and a certain intrinsic excellence of mind which, apart from its practical effects, appears to me to deserve the name of virtue. [For] many years it seemed to me perfectly self-evident that pleasure is the only good and pain the only evil. Now, however, the opposite seems to me self-evident.
What first turned me away from utilitarianism was the persuasion that I myself ought to pursue philosophy, although I had (and have still) no doubt that by doing economics and the theory of politics I could add more to human happiness. It appeared to me that the dignity of which human existence is capable is not attainable by devotion to the mechanism of life, and that unless the contemplation of eternal things is preserved, mankind will become no better than well-fed pigs. But I do not believe that such contemplation on the whole tends to happiness. It gives moments of delight, but these are outweighed by years of effort and depression.”

Bertrand Russell

Letter to Gilbert Murray, April 3, 1902
1900s

“I am sure that university life would be better, both intellectually and morally, if most university students had temporary childless marriages. This would afford a solution to the sexual urge neither restless nor surreptitious, neither mercenary nor casual, and of such a nature that it need not take up time which ought to be given to work.”

Bertrand Russell

"Sex in Education", p. 119-120
1930s, Education and the Social Order (1932)

“Mysticism is, in essence, little more than a certain intensity and depth of feeling in regard to what is believed about the universe.”

Bertrand Russell

Source: 1910s, Mysticism and Logic and Other Essays http://archive.org/stream/mysticism00russuoft/mysticism00russuoft_djvu.txt (1918), Ch. 1: Mysticism and Logic

“The reason that I call my doctrine logical atomism is because the atoms that I wish to arrive at as the sort of last residue in analysis are logical atoms and not physical atoms. Some of them will be what I call "particulars" – such things as little patches of color or sounds, momentary things – and some of them will be predicates or relations and so on.”

Bertrand Russell

1910s, The Philosophy of Logical Atomism (1918)

“The process of philosophizing, to my mind, consists mainly in passing from those obvious, vague, ambiguous things, that we feel quite sure of, to something precise, clear, definite, which by reflection and analysis we find is involved in the vague thing that we start from, and is, so to speak, the real truth of which that vague thing is a sort of shadow.”

Bertrand Russell

1910s, The Philosophy of Logical Atomism (1918)