Sir Karl Raimund Popper CH FBA FRS (July 28, 1902 – September 17, 1994) was an Austrian-British philosopher and professor. He is generally regarded as one of the greatest philosophers of science of the 20th century. (Click here for full Wikipedia article)
A rationalist, as I use the word, is a man who attempts to reach decisions by argument and perhaps, in certain cases, by compromise, rather than by violence.
All things living are in search of a better world.
Always remember that it is impossible to speak in such a way that you cannot be misunderstood: there will always be some who misunderstand you.
But I hold that he who teaches that not reason but love should rule opens up the way for those who rule by hate.
By reluctance to criticize some of it, we may help to destroy it all.
Do not allow your dreams of a beautiful world to lure you away from the claims of men who suffer here and now. Our fellow men have a claim to our help; no generation must be sacrificed for the sake of future generations, for the sake of an ideal of happiness that may never be realized.
Freedom is not a supplier who delivers goods to our door. Democracy does not ensure that anything is accomplished- certainly not an economic miracle.
I see now more clearly than ever before that even our greatest troubles spring from something that is as admirable and sound as it is dangerous- from our impatience to better the lot of our fellows.
If God had wanted to put everything into the universe from the beginning, He would have created a universe without change, without organisms and evolution, and without man and man's experience of change. But he seems to have thought that a live universe with events unexpected even by Himself would be more interesting than a dead one.
If we are uncritical we shall always find what we want: we shall look for, and find, confirmations, and we shall look away from, and not see, whatever might be dangerous to our pet theories.
It is our duty to help those who need help; but it cannot be our duty to make others happy...
It is wrong to think that belief in freedom always leads to victory; we must always be prepared for it to lead to defeat. If we choose freedom, then we must be prepared to perish along with it.
It seems to me certain that more people are killed out of righteous stupidity than out of wickedness.
No rational argument will have a rational effect on a man who does not want to adopt a rational attitude.
Our knowledge can be only finite, while our ignorance must necessarily be infinite.
Philosophers should consider the fact that the greatest happiness principle can easily be made an excuse for a benevolent dictatorship.
Science may be described as the art of systematic over-simplification- the art of discerning what we may with advantage omit.
Science must begin with myths, and with the criticism of myths.
The open society is one in which men have learned to be to some extent critical of taboos, and to base decisions on the authority of their own intelligence.
The true Enlightenment thinker, the true rationalist, never wants to talk anyone into anything. No, he does not even want to convince; all the time he is aware that he may be wrong.
Theories are nets cast to catch what we call 'the world': to rationalize, to explain, and to master it. We endeavor to make the mesh ever finer and finer.
There is an almost universal tendency, perhaps an inborn tendency, to suspect the good faith of a man who holds opinions that differ from our own opinions.
There is no history of mankind, there is only an indefinite number of histories of all kinds of aspects of human life.
Those who promise us paradise on earth never produced anything but a hell.
True ignorance is not the absence of knowledge, but the refusal to acquire it.
We are social creatures to the inmost center of our being. The notion that one can begin anything at all from scratch, free from the past, or unindebted to others, could not conceivably be more wrong.
We do not choose political freedom because it promises us this or that. We choose it because it makes possible the only dignified form of human coexistence, the only form in which we can be fully responsible for ourselves. Whether we realize its possibilities depends on all kinds of things- and above all on ourselves.
We may become the makers of our fate when we have ceased to pose as its prophets.
We must plan for freedom, and not only for security, if for no other reason than that only freedom can make security secure.
When I speak of reason or rationalism, all I mean is the conviction that we can learn through criticism of our mistakes and errors, especially through criticism by others, and eventually also through self-criticism.
Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.
You can choose whatever name you like for the two types of government. I personally call the type of government which can be removed without violence 'democracy', and the other 'tyranny.'.
You cannot have a rational discussion with a man who prefers shooting you to being convinced by you.