Some famous authors in the philosophy of physics (e.g. Dingler) have also incurred in the concept-swapping fallacy, witness his attempt to prove the law of causality (a synthetic judgment) by means of definitions. But it is in the so-called "theory of knowledge" or "epistemology" that we can see the fallacy at work from the very start. Although "epistemologists' claim to be Kant's successors, their very field of inquiry is incompatible with the critique of reason, and in fact is an egregious case of trying to derive synthetic judgments from mere concepts. The problem they set out to solve, viz the validity of our principles, requires an utterly different kind of inquiry, the one Kant called "deduction".