The critical attitude, the tradition of free discussion of theories with the aim of discovering their weak spots so that they may be improved upon, is the attitude of reasonableness, of rationality. It makes far-reaching use of both verbal argument and observation—of observation in the interest of argument, however. The Greeks’ discovery of the critical method gave rise at first to the mistaken hope that it would lead to the solution of all the great old problems; that it would establish certainty; that it would help to prove our theories, to justify them. But this hope was a residue of the dogmatic way of thinking; in fact nothing can be justified or proved (outside of mathematics and logic). The demand for rational proofs in science indicates a failure to keep distinct the broad realm of rationality and the narrow realm of rational certainty: it is an untenable, an unreasonable demand. 
Tag Archive: rationality
Questions of ultimate ends are not amenable to direct proof. Whatever can be proved to be good, must be so by being shown to be a means to something admitted to be good without proof. The medical art is proved to be good by its conducing to health; but how is it possible to prove that health is good? … There is a larger meaning of the word proof, in which this question is as amenable to it as any other of the disputed questions of philosophy. The subject is within the cognisance of the rational faculty; and neither does that faculty deal with it solely in the way of intuition. Considerations may be presented capable of determining the intellect either to give or withhold its assent to the doctrine; and this is equivalent to proof. [ch. I, 157-8]
To say that someone did something because he is a madman is to confess that we cannot really explain it at all. This is the fundamental insight, and the methodological point, behind the rationality principle.
The rationality principle is not the empirical hypothesis that each person acts adequately to the situation. That hypothesis is clearly false. It is, on the contrary, a methodological principle that places restrictions on what will and will not count as a rational explanation. It says that if we want to explain a social event rationally, then we must assume that the people in it acted adequately to the situation, or, at the very least, that they acted adequately to the situation as they saw it. 
For instance, it was one thing for a circumscribed group of intellectuals to discuss atheism, as had happened up to now, quite another to arrange for its popular diffusion and propaganda via a publishing campaign like that attempted without great success by adherents of the Radical Enlightenment. It was one thing for the different Christian denominations and the great revealed religions to be split by bloody and incomprehensible theological controversies. It was another matter entirely to posit point blank the idea of establishing a new universal and natural religion common to all the peoples in the world, a religion that was rational—devoid of dogmas, churches, hierarchies, and priests—and that would take hold first among the élites and then among the rest of the population. This implied the existence of a God who was very far away and frankly uninterested in human events, and whose sole function was that of granting the ultimate guarantee for man’s freedom and responsibility and none whatsoever for the authority of any Church. [xii]
This unbalanced (and immature) attitude is obsessed with the problem of power, not only over other men, but also over our natural environment — over the world as a whole. What I might call, by analogy, the ‘false religion’, is obsessed not only by God’s power over men but also by His power to create a world; similarly, false rationalism is fascinated by the idea of creating huge machines and Utopian social worlds. Bacon’s ‘knowledge is power’ and Plato’s ‘rule of the wise’ are different expressions of this attitude which, at bottom, is one of claiming power on the basis of one’s superior intellectual gifts. The true rationalist, in opposition, will always be aware of the simple fact that whatever reason he may possess he owes to intellectual intercourse with others. He will be inclined, therefore, to consider men as fundamentally equal, and human reason as a bond which unites them. Reason for him is the precise opposite of an instrument of power and violence: he sees it as a means whereby they may be tamed. 
Scientists are like architects who build buildings of different sizes and different shapes and who can be judged only after the event, i.e. only after they have finished their structure. It may stand up, it may fall down – nobody knows.