but also for a special theory of knowledge under which the outcome of scientific activity has, to Pearson's satisfaction, been subsumed; logic has become the master. The same logic is, none the less, an indispensable servant. We may set aside the whole business of making systems: yet we shall never plan an investigation, or carry out a research, or. present our results to our fellow workers, without calling in the aid of logic. Scientific activity and logical activity are always and everywhere intermingled; a book like Jevons' "Principles of Science" is, in the nature of the case, very largely a logic; it is logic that adds the subjunctive and imperative moods to Poincaré's scientific indicative. And if, for all these reasons, the clean distinction of the two activities is intrinsically difficult, it becomes the more so in the concrete case, seeing that the specialist in science is likely to employ a special logic, the logic of his special point of view and of the "facts" which that point of view discloses, so that he seems presently to work by "intuition" and the activities appear to have been blended rather than intermixed.
Still, the activities are in themselves different; and in the main, in the broad, our thinking must recognize their difference. We are, again, not to split hairs, or to attempt any hard and fast distinction. But let the reader take up a text-book—that very practical thing—in some one of the newer sciences; let him go through it, pencil in hand; and let him mark, as he reads, the passages that are derived from scientific activity on the writer's part and the passages that are logical. Sometimes, of course, he will be in doubt; and the doubtful passages, since we are making but a rough and ready test, may be left unmarked. They will occur most often in the early chapters of the book,—partly because the introductory chapters are likely to be of a general character, partly because the reader is not yet skilled to distinguish the one sort of writing from the other. As more and more pages are turned, the marking becomes easier, more prompt and more certain; the reader feels that he has the key to the cryptogram; and the result is instructive enough to warrant the few hours that have been given to the task.
IV
We may sum up these paragraphs in the statement that science is defined by its point of view. The scientific man looks out upon experience from a certain standpoint; sees and can see his world only under one aspect; and by this attitude, which he has taken up toward experience, is limited to a particular type of method and to a particular type of problem. To invite him from his "academic reserve," or to demand that he interest himself in "practical ends," is simply to bid him cease from scientific activity. The scientific man, again, is logical, just as the historian or the jurist is logical; but logic is not science; and within science the facts of observation take precedence, and logical
