Where two principles really do meet which cannot be reconciled with one another, then each man declares the other a fool and a heretic - Ludwig Wittgenstein

At the core of all well-founded belief lies belief that is unfounded.

All testing, all confirmation and disconfirmation of a hypothesis takes place already within a system. And this system is not a more or less arbitrary and doubtful point of departure for all our arguments: no, it belongs to the essence of what we call an argument. The system is not so much as the point of departure, as the element in which arguments have their life.

Most propositions and questions, that have been written about philosophical matters, are not false, but senseless. We cannot, therefore, answer questions of this kind at all, but only state their senselessness. Most questions and propositions of the philosophers result from the fact that we do not understand the logic of our language.