Behaviorism’s substitute for the mind is certain entities in the environment
called “reinforcers.” A “reinforcer,” say the Behaviorists, is an event which
follows a response and makes subsequent responses of the same type more likely.
“What type of events change the probability of responding?” we ask.
“Reinforcing events,” we are told. “What is a reinforcing event?” we inquire.
“One which modifies response probability,” they reply. “Why does a reinforcer
reinforce?” we ask. “That’s not a relevant question,” they answer. . . . To
understand why a “reinforcer” reinforces, Behaviorists would have to make
reference to the individual’s mental contents and processes—i.e., they would
have to abandon Behaviorism.