Arguments purporting to justify beliefs or evaluations often proceed from specific to more general issues. Opposition and challenge tend to provoke critical reflection; through various dialectical moves higher levels of justification are reached and made explicit. Argument usually terminates with appeals to principles which are considered indisputable, at least by those who invoke them. But, notoriously, initial disagreements cannot always be removed by what is called "rational argument." Frequently enough, initial disagreement can be traced back to disagreement in basic presuppositions. It is a characteristic of those modern cultures which endorse freedom of thought that they countenance divergencies in religious, political, or economic positions. "It is all a matter of one's ultimate presuppositions' — this phrase and its variants indicate that enlightened common sense is aware of the limits of argument and justification. But on the other hand there is also the deep-rooted wish to be right, absolutely right, in one's basic outlook. When the disagreement concerns mere gastronomical matters, we are quite willing to reconcile ourselves with the saying, "De gustibus non est disputandum." Art critics and aestheticians, however, do not unreservedly extend such tolerance to all issues of aesthetic evaluation. Most people, including the majority of philosophers, are still more reluctant to grant any relativity to the basic standards of moral evaluation. There is, at least in this age of science, almost complete unanimity as regards the criteria by which we judge the claims of ordinary factual knowledge. And perhaps genuine indisputability is attributed to the principles of formal logic. At least the simplest canons of deductive reasoning, as they are exemplified, e.g., in some of the syllogisms or in elementary arithmetic, are quite generally accepted as indispensable presuppositions of any sort of argument.