THE A EDITION PREFACE: THE PROBLEM OF HUMAN REASON
In the first edition Preface Kant explains why a critique of human reason – the power to know – is necessary. At Avii he says it is the nature of reason to ask questions it cannot answer. Although he gives no examples, these questions are the basis of traditional metaphysical disputes Kant examines in the Transcendental Dialectic: is the universe finite or infinite in space and time? Is matter infinitely divisible or composed of simple parts? Do humans have free will or are we determined by causes outside our control? And does the existence of the universe presuppose a necessarily existent being? We can see how these questions arise in our everyday thinking. Consider the principle underlying scientific investigation: “Every event has a cause.” We “naturally” ask: what caused the earthquake? What causes the earth to revolve around the sun? What caused the universe? But if these questions arise naturally, then what is the problem?
In the Dialectic, Kant describes how, in trying to explain reality, reason ends up in a dilemma: either the explanatory chain continues forever, or it must end somewhere. The temptation is to find a stopping place, to invent an “absolute” to end the series. Examples of such “absolutes” are God as the cause of the universe, and freely acting souls as the causes of human actions. The problem with such answers is that they cannot be verified by experience.