The scandal of metaphysics

Start with an observation Kant treats as plain fact. Some fields of human knowledge progress. Mathematics has advanced steadily since the Greeks; nobody reopens whether the angles of a triangle sum to two right angles. Natural science, since Galileo and Newton, marches from result to result, each generation standing on the last. In these fields, disputes get settled, and what is settled stays settled.

Now look at metaphysics — the attempt to know, by pure reason, the ultimate nature of things: whether God exists, whether the soul is immortal, whether the world had a beginning, whether we are free. Here there is no march. The same questions are fought over in every century, by brilliant people, with no resolution and no agreement. Kant’s own image in the Prolegomena is of thinkers “constantly moving round the same spot without gaining a single step” — endless, circular controversy that never advances. Prolegomena to Any Future Metaphysics Preface

So Kant refuses the obvious move. The obvious move, when metaphysics is stuck, is to do more metaphysics — propose your own system and hope it wins. Kant steps back instead and asks a question no dogmatist thinks to ask: is the whole enterprise even legitimate? Before adding to the pile, he wants to know whether pure reason has any right to the territory it keeps fighting over.

The book’s central question, then, is this: is metaphysics possible at all? Notice the order. Not “which metaphysics is true?” but first, and more radically, “can there be a science of these matters?” Only if the answer is yes does the second question — how is it possible? — even arise. Kant insists we have no right to skip the first question, and that skipping it is precisely what everyone before him did.

What makes metaphysics so distinctive — and so suspect — is what it claims to reach. Mathematics and physics stay tethered, one way or another, to what can be given in experience. Metaphysics claims to know things that lie beyond all possible experience: God, the immortal soul, the world as a completed whole, freedom of the will. It proposes to know these by pure reason alone, with no help from the senses. That ambition is exactly what makes it both alluring — it promises the answers we most want — and deeply questionable.

This sets up the stakes as a three-way fork, which will organize everything to come. The skeptic (Hume, at his most radical) says: since these claims can never be grounded in experience, metaphysics is impossible — abandon it. The dogmatist (the confident rationalist) says: reason plainly does reach these truths, so metaphysics needs no examination — just get on with it. Kant thinks both are wrong, and he will carve a third way between them.