• Our knowledge can only be finite, while our ignorance must necessarily be infinite.
• A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of theory (as people often think) but a vice.
• Good tests kill flawed theories; we remain alive to guess again.
• Philosophers should consider the fact that the greatest happiness principle can easily be made an excuse for a benevolent dictatorship. We should replace it by a more modest and more realistic principle / the principle that the fight against avoidable misery should be a recognized aim of public policy, while the increase of happiness should be left, in the main, to private initiative.
• Those who promise us paradise on earth never produced anything but a hell.
• We all remember how many religious wars were fought for a religion of love and gentleness; how many bodies were burned alive with the genuinely kind intention of saving souls from the eternal fire of hell.
• It is often asserted that discussion is only possible between people who have a common language and accept common basic assumptions. I think that this is a mistake. All that is needed is a readiness to learn from one's partner in the discussion, which includes a genuine wish to understand what he intends to say. If this readiness is there, the discussion wrighteous stupidityill be the more fruitful the more the partner's backgrounds differ.
• True ignorance is not the absence of knowledge, but the refusal to acquire it.
• The game of science is, in principle, without end. He who decides one day that scientific statements do not call for any further test, and that they can be regarded as finally verified, retires from the game.
• The more we learn about the world, and the deeper our learning, the more conscious, specific, and articulate will be our knowledge of what we do not know, our knowledge of our ignorance.

• The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what's true. We have a method, and that method helps us to reach not absolute truth, only asymptotic approaches to the truth - never there, just closer and closer, always finding vast new oceans of undiscovered possibilities. Cleverly designed experiments are the key.
• I worry that, especially as the Millennium edges nearer, pseudo-science and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive. Where have we heard it before? Whenever our ethnic or national prejudices are aroused, in times of scarcity, during challenges to national self-esteem or nerve, when we agonize about our diminished cosmic place and purpose, or when fanaticism is bubbling up around us-then, habits of thought familiar from ages past reach for the controls. The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir.
• Credulity kills.
• Humans may crave absolute certainty; they may aspire to it; they may pretend, as partisans of certain religions do, to have attained it. But the history of science - by far the most successful claim to knowledge accessible to humans - teaches that the most we can hope for is successive improvement in our understanding, learning from our mistakes, an asymptotic approach to the Universe, but with the proviso that absolute certainty will always elude us.
• At the heart of science is an essential tension between two seemingly contradictory attitudes - an openness to new ideas, no matter how bizarre or counterintuitive they may be, and the most ruthless skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense.
• Who is more humble? The scientist who looks at the universe with an open mind and accepts whatever the universe has to teach us, or somebody who says everything in this book must be considered the literal truth and never mind the fallibility of all the human beings involved?
• ...that kind of skeptical questioning, don't accept what authority tells you - attitude of science - is also nearly identical to the attitude of mind necessary for a functioning democracy. Science and democracy have very consonant values and approaches, and I don't think you can have one without the other.

• A person may cause evil to others not only by his actions but by his inaction, and in either case he is justly accountable to them for the injury.
• If all mankind minus one were of one opinion, mankind would be no more justified in silencing that one person than he, if he had the power, would be justified in silencing mankind.
• I have learned to seek my happiness by limiting my desires, rather than in attempting to satisfy them.
• We have a right, also, in various ways, to act upon our unfavorable opinion of anyone, not to the oppression of his individuality, but in the exercise of ours.
• The worth of the state, in the long run, is the worth of the individuals composing it.
• The principle itself of dogmatic religion, dogmatic morality, dogmatic philosophy, is what requires to be rooted out; not any particular manifestation of that principle.

• Economics is a theoretical science and as such abstains from any judgement of value. It is not its task to tell people what ends they should aim at. It is a science of the means to be applied for attainment of ends chosen, not, to be sure, a science of the choosing of ends. Ultimate decisions, the valuations and the choosing of ends, are beyond the scope of any science. Science never tells a man how he should act; it merely shows how a man must act if he wants to attain definite ends.
• There is in the universe something for the description and analysis of which the natural sciences cannot contribute anything. There are events beyond the range of those events that the procedures of the natural sciences are fit to observe and describe. There is human action.
• The methods of the natural sciences cannot be applied to human behavior because this behavior...lacks the peculiarity that characterizes events in the field of the natural sciences, viz., regularity.
• Facts per se can neither prove nor refute anything. Everything is decided by the interpretation and explanation of the facts, by the ideas and the theories.
• It is the worst of all superstitions to assume that the epistemological characteristics of one branch of knowledge must necessarily be applicable to any other branch.

• It is rather a problem of how to secure the best use of resources known to any of the members of society, for ends whose relative importance only those individuals know.
• There is all the difference in the world between treating people equally and attempting to make them equal.
• The more the state 'plans' the more difficult planning becomes for the individual.
• Only where we ourselves are responsible for our own interests and are free to sacrifice them has our decision moral value. We are neither entitled to be unselfish at someone else's expense nor is there any merit in being unselfish if we have no choice. The members of a society who in all respects are made to do the good thing have no title to praise.
• This is not a dispute about whether planning is to be done or not. It is a dispute as to whether planning is to be done centrally, by one authority for the whole economic system, or is to be divided among many individuals.
• Ever since the beginning of modern science, the best minds have recognized that "the range of acknowledged ignorance will grow with the advance of science." "In science the more we know, the more extensive the contact with nescience." Unfortunately, the popular effect of this scientific advance has been a belief, seemingly shared by many scientists, that the range of our ignorance is steadily diminishing and that we can therefore aim at more comprehensive and deliberate control of all human activities. It is for this reason that those intoxicated by the advance of knowledge so often become the enemies of freedom...The more men know, the smaller the share of all that knowledge becomes that any one mind can absorb. The more civilized we become, the more relatively ignorant must each individual be of the facts on which the working of his civilization depends.
• Before we can try to remould society intelligently, we must understand its functioning; we must realise that, even when we believe that we understand it, we may be mistaken. What we must learn to understand is that human civilisation has a life of its own, that all our efforts to improve things must operate within a working whole which we cannot entirely control, and the operation of whose forces we can hope merely to facilitate and assist so far as we can understand them.
• I confess that I prefer true but imperfect knowledge, even if it leaves much indetermined and unpredictable, to a pretence of exact knowledge that is likely to be false. The credit which the apparent conformity with recognized scientific standards can gain for seemingly simple but false theories may, as the present instance shows, have grave consequences.

• It is better to be roughly right than precisely wrong.
• When the facts change, I change my mind.
• There is no harm in being sometimes wrong - especially if one is promptly found out.
• The long run is a misleading guide to current affairs. In the long run we are all dead.
• Marxian Socialism must always remain a portent to the historians of Opinion - how a doctrine so illogical and so dull can have exercised so powerful and enduring an influence over the minds of men, and, through them, the events of history.
• The ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood. Indeed the world is ruled by little else. Practical men, who believe themselves to be quite exempt from any intellectual influence, are usually the slaves of some defunct economist.
• Education: the inculcation of the incomprehensible into the indifferent by the incompetent.

• True individual freedom cannot exist without economic security and independence. People who are hungry and out of a job are the stuff of which dictatorships are made.

• What can be said at all can be said clearly; and whereof one cannot speak thereof one must be silent.
• The aspects of things that are most important for us are hidden because of their simplicity and familiarity.
• At the end of reasons comes persuasion.

• Real economists don't talk about competitiveness.

• A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeed be in a poor way if he had to be restrained by fear of punishment and hope of reward after death.
• I believe in Spinoza's God, Who reveals Himself in the lawful harmony of the world, not in a God Who concerns Himself with the fate and the doings of mankind.