1) The philosophy of the science of human behavior. It is the position that we can study behavior scientifically and that we do so by finding the variables of which it is a function. Modern behaviorism is further separated into methodological behaviorism, which holds that the behavior we can study is only that which can be measured by two independent observers (thus excluding all inner behavior) , and radical behaviorism, which includes inner behaviors such as "thoughts" and "dreams" as valid behavior to investigate. B.F. Skinner is the leading spokesman for radical behaviorism, which is the position taken in this book.

2) The scientific philosophy of behavior analysis.