"There are more fools in the world than there are people." - Heinrich Heine

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"Since all argument must proceed from assumptions, it is plainly impossible to demand that all assumptions should be based on argument. The demand raised by many philosophers that we should start with no assumption whatever and never assume anything about 'sufficient reason', and even the weaker demand that we should start with a very small set of assumptions ('categories'), are both in this form inconsistent. For they themselves rest upon the truly colossal assumption that it is possible to start without, or with only a few assumptions, and still to obtain results that are worth while...

The irrationalist insists that emotions and passions rather than reason are the mainsprings of human action. To the rationalist's reply that, though this may be so, we should do what we can to remedy it, and should try to make reason play as large a part as it possibly can, the irrationalist would rejoin (if he condescends to a discussion) that this attitude is hopelessly unrealistic. For it does not consider the weakness of 'human nature', the feeble intellectual endowment of most most (sic) and their obvious dependence upon emotions and passions...

He who teaches that not reason but love should rule opens the way for those who rule by hate... Love as such certainly does not promote impartiality. And it cannot do away with conflict either... The greater the love, the stronger will be the conflict. There are only two solutions: one is the use of emotion, and ultimately of violence, and the other is the use of reason, of impartiality, of reasonable compromise... No emotion, not even love, can replace the rule of institutions controlled by reason...

Loving a person means wishing to make him happy... but of all political ideals, that of making the people happy is perhaps the most dangerous one. It leads invariably to the attempt to impose our scale of 'higher' values upon others, in order to make them realize what seems to us of greatest importance for their happiness; in order, as it were, to save their souls. It leads to Utopianism and Romanticism. We all feel certain that everybody would be happy in the beautiful, the perfect community of our dreams. And no doubt, there would be heaven on earth if we could all love one another. But, as I have said before... the attempt to make heaven on earth invariably produces hell. It leads to intolerance. It leads to religious wars, and to the saving of souls through the inquisition. And it is, I believe, based on a complete misunderstanding of our moral duties. It is our duty to help those who need our help; but it cannot be our duty to make others happy... Thus we might say: help your enemies; assist those in distress, even if they hate you; but love only your friends...

The adoption of rationalism implies, moreover, that there is a common medium of communication, a common language of reason; it establishes something like a moral obligation towards that language, the obligation to keep up its standards of clarity and to use it in such a way that it can retain its function as the vehicle of argument. That is to say, to use it plainly; to use it as an instrument of rational communication, of significant information, rather than as a means of 'self-expression', as the vicious romantic jargon of most of our educationists has it... Mankind is united by the fact that our different mother tongues, in so far as they are rational, can be translated into one another. It recognizes the unity of human reason...

Rationalism is critical, whilst irrationalism must tend towards dogmatism (where there is no argument, nothing is left but full acceptance or flat denial)... Criticism always demands a certain degree of imagination, whilst dogmatism suppresses it... It is humanly impossible for us to love, or to suffer with, a great number of people; nor does it appear to me very desirable that we should, since it would ultimately destroy either our ability to help or the intensity of these very emotions... We can love mankind only in certain concrete individuals. But by the use of thought and imagination, we may become ready to help all who need our help...

A rationalist attitude seems to be usually combined with a basically equalitarian and humanitarian outlook; irrationalism, on the other hand, exhibits in most cases at least some of the anti-equalitarian tendencies described."

--- The Open Society and Its Enemies, Volume 2 / Karl Popper: