Behaviorism was a prominent theory of psychology in the early twentieth century, intended to make human behavior more susceptible to quantitative experiment. Its philosophy is that psychology should be understood in terms of what’s observable: current/historical environmental stimuli and their consequent behaviors. Learning is assumed to be an automatic process, shaping behavior in response to associations between events and their consequences.
A key challenge for this approach is that behavior is often the result of interpretation, beliefs, conceptions, memories—internal, non-observable phenomena. If we don’t include them in our theories, we’ll be misled. See The cognitive revolution
Q. What motivated behaviorism’s emphasis on stimuli and behaviors?
A. A drive to form theories based only on what’s observable.
Q. What’s the problem for behaviorism with your response to “This needs sodium chloride; could you help?”
A. You’d pass the salt, but that’s not a conditioned response to a stimulus: you’re using your knowledge to understand what the request means.