Deliberation and decision (W. Heisenberg 1958)

But remembering our experience in modern physics it is easy to see that there must be a fundamental complementarity between deliberation and decision. In the practical decisions of life it will scarcely ever be possible to go through all the arguments in favor of or against one possible decision, and one will therefore always have to act on insufficient evidence. The decision finally takes place by pushing away all the arguments - both those that have been understood and others that might come up through further deliberation - and by cutting off all further pondering. The decision may be the result of deliberation, but it is at the same time complementary to deliberation; it excludes deliberation. Even the most important decision in life must always contain this inevitable element of irrationality.

The decision itself is necessary, since there must be something to rely upon, some principle to guide our actions. Without such a firm stand our own actions would lose all force. Therefore, it cannot be avoided that some real or apparent truth form the basis of life; and this fact should be acknowledged with regard to those groups of people whose basis is different from our own.

Werner Heisenberg. Physics and Philosophy. The revolution in modern science. 1958. Pag. 205.