If I were a science journalist myself, I would still want to draw lessons from Freud, not about the unconscious but about the classic ingredients of a pseudoscience. Freud, we need to realize, created the most ingenious and thoroughgoing pseudoscience ever devised. To grasp its slippery rationale is to be forearmed against similar enterprises that may happen along.

As the late philosopher Frank Cioffi convincingly maintained, a pseudoscience can be recognized not by its false claims but by the behavior of its proponents when one of their beliefs is disconfirmed or shown to be vacuous. Then the defenders will either dispute the refutation, cite imaginary proofs, slander the critic, co-opt the criticism by attaching ad hoc provisos to their doctrine, or pretend that their theory meant something else altogether.

Freud prolifically employed all five tactics, with the result that, even within his lifetime, psychoanalytic discourse became a vast jumble of contradictions, rhetorical dodges, and escape clauses. But Freud went farther still, first by invoking uniquely self-confirming rules of interpretation and then by nullifying all objections in advance of hearing them. He included, within his theory itself, a “clinical diagnosis” of the pathological urge to “resist” psychoanalytic truth. Neither astrology nor Mesmerism nor phrenology ever approached this apogee of combined delusion and deception.