According to Kant, a true judgement can be called a priori in case it can take place absolutely (schlechterdings) independent of experience. Propositions that are knowable in this way are called a priori propositions by him (Kant 1787 B, 3–4). As is well known, the class of those a priori propositions that are synthetic was particularly important for Kant. In contrast to analytic propositions, they are supposed to contain nontrivial information about the world and yet be irrefutable by experience. Not many of his critics were satisfied with Kant's way of drawing this distinction. Peter Strawson, for example, writes in his commentary on the Critique of Pure Reason: