Watson was the father of behaviorism. His now-revered lectures on the subject defined behaviorism as a natural science that takes the whole field of human adjustment as its own. It is the business of behaviorist psychology to predict and control human activity. The field has as its aim to be able, given the stimulus, to predict the response, or seeing the reaction, to know the stimulus that produced it. Watson argued that psychology is as good as its observations: what the organism does or says in the general environment.

Watson identified "laws" of learning, including frequency and...