B. F. Skinner

American psychologist who developed operant conditioning theory — behavior is shaped by its consequences — and argued for a radical behaviorist account of language in Verbal Behavior.

Operant conditioning: behavior is selected by reinforcement schedules; the environment determines behavior through contingencies of reinforcement; there is no need to posit internal mental states. Verbal Behavior: language is verbal behavior shaped by reinforcement, not syntactic rule-following.