If these phenomena are to be brought within the scope of behaviourist psychology, it must be by means of “implicit” behaviour. Watson makes much use of this in the form of talking to oneself, but in apes it cannot take quite this form. And it is necessary to have some theory to explain the success of “implicit” behaviour, whether we call it “thought” or not. Perhaps such a theory can be constructed on Watson’s lines, but it has certainly not yet been constructed. Until the behaviourists have satisfactorily explained the kind of discovery which appears in Köhler’s observations, we cannot say that their thesis is proved. This is a matter which will occupy us again at a later stage; for the present let us preserve an open mind. CHAPTER IV LANGUAGE The subject of language is one which has not been studied with sufficient care in traditional philosophy. It was taken for granted that words exist to express “thoughts,” and generally also that “thoughts” have “objects” which are what the words “mean”. It was thought that, by means of language, we could deal directly with what it “means”, and that we need not analyse with any care either of the two supposed properties of words, namely that of “expressing” thoughts and that of “meaning” things. Often when philosophers intended to be considering the objects meant by words they were in fact considering only the words, and when they were considering words they made the mistake of supposing, more or less unconsciously, that a word is a single entity, not, as it really is, a set of more or less similar events. The failure to consider language explicitly has been a cause of much that was bad in traditional philosophy. I think myself that “meaning” can only be understood if we treat language as a bodily habit, which is learnt just as we learn football or bicycling. The only satisfactory way to treat language, to my mind, is to treat it in this way, as Dr. Watson does. Indeed, I should regard the theory of language as one of the strongest points in favour of behaviourism.