Philosophers have sometimes supposed that Behaviorists are, as such committed to the idea that our ordinary mentalistic concepts are analyzable in terms of overt behavior. But although behaviorism has often been characterized by a certain,metaphysical bias, it is not a thesis about the analysis of existing psychological concepts, but one which concerns the construction of new concepts. As a methodological thesis, it involves no commitment whatever concerning the logical analysis of common-sense mentalistic discourse, nor does it involve a denial that each of us has a privileged access to our state of mind, nor that these states of mind can properly be described in terms of such common-sense concepts as believing, wondering, doubting, intending, wishing, inferring, etc. If we permit ourselves to speak of this privileged access to our states of mind as "introspection," avoiding the implication that there is a "means" whereby we "see" what is going on "inside," as we see external circumstances by the eye, then we can say that Behaviorism, as I shall use the term, does not deny that there is such a thing as introspection, nor that it is, on some topics, at least, quite reliable. The essential point about 'introspection' from the standpoint of Behaviorism is that we introspect in terms of common sense mentalistic concepts. And while the Behaviorist admits, as anyone must, that much knowledge is embodied in common-sense mentalistic discourse, and that still more can be gained in the future by formulating and testing hypotheses in terms of them, and while he admits that it is perfectly legitimate to call such a psychology "scientific," he proposes, for his own part, to make no more than a heuristic use of mentalistic discourse, and to construct his concepts "from scratch" in the course of developing his own scientific account of the observable behavior of human organisms.

    54. But while it is quite clear that scientific Behaviorism is not the thesis that common-sense psychological concepts are analyzable into concepts pertaining to overt behavior -- a thesis which has been maintained by some philosophers and which may be called 'analytical' or 'philosophical' Behaviorism -- it is often thought that Behaviorism is committed to the idea that the concepts of a behavioristic psychology must be so analyzable, or, to put things right side up, that properly introduced behavioristic concepts must be built by explicit definition -- in the broadest sense -- from a basic vocabulary pertaining to overt behavior. The Behaviorist would thus be saying "Whether or not the mentalistic concepts of everyday life are definable in terms of overt behavior, I shall ensure that this is true of the concepts that I shall employ." And it must be confessed that many behavioristically oriented psychologists have believed themselves committed to this austere program of concept formation.

    Now I think it reasonable to say that, thus conceived, the behavioristic program would be unduly restrictive. Certainly, nothing in the nature of sound scientific procedure requires this self-denial. Physics, the methodological sophistication of which has so impressed -- indeed, overly impressed -- the other sciences, does not lay down a corresponding restriction on its concepts, nor has chemistry been built in terms of concepts explicitly definable in terms of the observable properties and behavior of chemical substances. The point I am making should now be clear. The behavioristic requirement that all concepts should be introduced in terms of a basic vocabulary pertaining to overt behavior is compatible with the idea that some behavioristic concepts are to be introduced as theoretical concepts.

    55. It is essential to note that the theoretical terms of a behavioristic psychology are not only not defined in terms of overt behavior, they are also not defined in terms of nerves, synapses, neural impulses, etc., etc. A behavioristic theory of behavior is not, as such, a physiological explanation of behavior. The ability of a framework of theoretical concepts and propositions successfully to explain behavioral phenomena is logically independent of the identification of these theoretical concepts with concepts of neurophysiology. What is true -- and this is a logical point -- is that each special science dealing with some aspect of the human organism operates within the frame of a certain regulative ideal, the ideal of a coherent system in which the achievements of each have an intelligible place. Thus, it is part of the Behaviorist's business to keep an eye on the total picture of the human organism which is beginning to emerge. And if the tendency to premature identification is held in check, there may be considerable heuristic value in speculative attempts at integration; though, until recently, at least, neurophysiological speculations in behavior theory have not been particularly fruitful. And while it is, I suppose, noncontroversial that when the total scientific picture of man and his behavior is in, it will involve some identification of concepts in behavior theory with concepts pertaining to the functioning of anatomical structures, it should not be assumed that behavior theory is committed ab initio to a physiological identification of all its concepts, -- that its concepts are, so to speak, physiological from the start.

    We have, in effect, been distinguishing between two dimensions of the logic (or 'methodologic') of theoretical terms: (a) their role in explaining the selected phenomena of which the theory is the theory; (b) their role as candidates for integration in what we have called the "total picture." These roles are equally part of the logic, and hence the "meaning," of theoretical terms. Thus, at any one time the terms in a theory will carry with them as part of their logical force that which it is reasonable to envisage -- whether schematically or determinately -- as the manner of their integration. However, for the purposes of my argument, it will be useful to refer to these two roles as though it were a matter of a distinction between what I shall call pure theoretical concepts, and hypotheses concerning the relation of these concepts to concepts in other specialties. What we can say is that the less a scientist is in a position to conjecture about the way in which a certain theory can be expected to integrate with other specialties, the more the concepts of his theory approximate to the status of pure theoretical concepts. To illustrate: We can imagine that Chemistry developed a sophisticated and successful theory to explain chemical phenomena before either electrical or magnetic phenomena were noticed; and that chemists developed as pure theoretical concepts, certain concepts which it later became reasonable to identify with concepts belonging the framework of electromagnetic theory.