The following is missing for the question to be complete:
B. F. Skinner
William James
Sigmund Freud
Carl Rogers
Answer: B.F. Skinner
Explanation: B.F.Skinner is an American psychologist, behaviourist who has developed a theory of operative conditioning, arguing that behaviour can be shaped by its consequences. Each behaviour has a specific outcome and depending on the desirability of the outcome may be answered by reinforcements or penalties. In any case, with reinforcements and punishments, it is certain that certain behaviour will be repeated. He is also the creator of the so-called radical behaviourism according to which everyone has some innate behaviour, that is, behaviour is dependent on genes.
Skinner argued that internal mental processes, events, and states existed, though he felt that these internal events could not be taken as relevant to explain one's behaviour. Since behaviour can be studied and shaped by reinforcements or punishments, that is, it can only be objectively studied and shaped that can be observed, i.e externally behaviour, independent of internal events and states, such as thoughts, emotions, etc.
