As data are signs which _indicate_ other existences, so meanings are signs which _imply_ other meanings.[8] I am doubtful, for example, whether _this_ is a man or not; that is, I am doubtful as to some given traits when they are taken as signs or evidences, but I am inclined to the hypothesis of a man. Having such a tentative or conceptual object in mind, I am enabled to explore economically and effectively, instead of at random, what is present, _provided_ I can elaborate the implications of the term "man." To develop its implications is all one with telling its meaning in connection with other meanings. Being a man means, for example, speaking when spoken to--another meaning which need have been no part of "man" as originally suggested. This meaning of "answering questions" will then suggest a procedure which the term "man" in its first meaning did not possess; it is an implication or implied meaning which puts me in a new and possibly more fruitful relation to the thing. (The process of developing implications is usually termed "discourse" or ratiocination.) Now, be it noted, replying to questions is no part of the _definition_ of man; it would not be now an implication of Plato or of the Russian Czar for me. In other words, there is something in the actual situation which suggests _inquiring_ as well as _man_; and it is the interaction between these two suggestions which is fruitful. There is consequently no mystery about the fruitfulness of deduction--though this fruitfulness has been urged as though it offered an insuperable objection to instrumentalism. On the contrary, instrumentalism is the only theory to which deduction is not a mystery. If a variety of wheels and cams and rods which have been invented with reference to doing a given task are put together, one expects from the assembled parts a result which could not have been got from any one of them separately or from all of them together in a heap. Because they are independent and unlike structures, working on one another, something new happens. The same is true of terms in relation to one another. When these are brought to bear upon one another, something new, something quite unexpected happens, quite as when one tries an acid with which he is not familiar upon a rock with which he is unfamiliar--that is, unfamiliar in such a conjunction, in spite of intimate acquaintance elsewhere. A definition may fix a certain modicum of meaning in the abstract, as we say; it is a specification of a minimum which gives the point of departure in every interaction of a term with other terms. But nothing follows from the definition by itself or in isolation. It is explicit (boringly so) and has no implications. But bring it in connection with another term with which it has not previously interacted and it may behave in the most delightful or in the most disgustingly disappointing way. The necessity for independent terms is made obvious in the modern theory of axioms.