Critics of behaviorism maintain that the organization of behavior cannot be explained without reference to purpose. Although behaviorists object to teleological explanations, they admit that behavior manifests purposive features such as persistence and flexibility. They attempt to explain these features by theories which do not refer to purpose as a final cause or conscious content.
According to one such theory, purpose is a state variable that changes the relationship between stimuli and responses. In a second theory, purposive qualities result from the conditioning of responses to persisting stimuli arising from various motivational states. Reinforcement theories of purpose explain the purposive qualities of behavior as due to previous contingencies of reinforcement rather than future rewards.
In state variable theories of purpose, intention is identified with a readiness to respond. In mediational theories, it can be identified with the anticipatory goal reaction or with implicit trial and error. In yet other theories, it is related to the verbal control of behavior.
Chomsky claims that the organization of verbal behavior cannot be adequately explained without reference to a generative grammar. His claim that verbal behavior is not under the control of behavioral variables is either a justified rejection of the simple reflexological model or a premature and unsupported speculation. His rejection of finite state grammars refutes the simple reflexological model but not major S-R theories which incorporate state variables, functional response classes, response hierarchies, mediation, and autoclitics, all of which differ from left-right sequencing.
Chomsky's competence model, the generative grammar, can be interpreted as a structural description of functional stimulus and response classes. As such, it is an intervening variable and does not describe processes within the organism. Nor is it more deep, more abstract, or more hidden than other theoretical concepts. If it is interpreted as a hypothetical construct, then it is a poorly defined one.