Definition
Determinism is the view that every event is fully caused by the events preceding it. Applied to human beings, it holds that a choice is the necessary outcome of a person's biology and history — genes, brain state, hormones, experience, and the immediate situation all converging on a single result.
Behave is, in effect, a long argument for behavioral determinism: that a complete causal story can be told for any action, with nothing left over.
Why it matters
How it works
Behave builds the deterministic picture additively. A behavior is preceded by neural activity, which is preceded by that day's hormonal state, by the brain shaped in adolescence and childhood, by prenatal environment, by genes, and by the culture and ecology that produced all of it. Each layer is a set of causes the actor did not select.
Determinism is the metaphysical claim; what people do with it is contested.