The mind is not a blank slate shaped purely by experience

Pinker's central target is the twentieth-century behaviorist and social-constructivist assumption that newborns arrive with essentially no built-in psychological content, and that adult personality, intelligence, and behavior are almost entirely the product of upbringing and culture. He marshals evidence from twin studies, cross-cultural psychology, and cognitive science showing consistent patterns — universal facial expressions, predictable developmental stages, shared grammatical structures across unrelated languages — that are hard to explain if the mind starts as a blank canvas.

He's careful to distinguish this claim from genetic determinism: acknowledging innate structure doesn't mean environment is irrelevant, only that genes and environment interact rather than environment acting alone on an empty system. The blank slate view persisted, he argues, partly because it seemed to guarantee equality — if nothing is innate, no group could be innately different from another.

Takeaway: denying innate structure to protect equality was always resting equality on a fragile, falsifiable foundation.