Page:Philosophical Review Volume 21.djvu/728

710 and emphasis of similarities and differences, become the bases for conclusions and predictions the latter, the main function of science. But there are always extraneous elements present due to necessarily limited observation, and so the natural law which emerges is valid for "ideal cases" rather than for the particular phenomena of observation. In his own words: "A series of instances are investigated which are so adjusted that the influence of the extraneous grows less and less. Then the relation investigated approaches a limit which is never quite reached, but to which it draws nearer and nearer, the less the influence of the extraneous elements. And the conclusion is drawn that if it were possible to exclude the extraneous elements entirely, the limit of the relation would be reached. ... We here confront the fact that many natural laws, and among them the most important, are expressed as, and taken to be, conditions which never occur in reality."

The correspondence between "ideal cases" and phenomena becomes closer according as the inner interconnection and continuity of phenomena becomes known. Consequently, the various sciences will be found to have an organic and developmental connection, and so may be put in systematic arrangement. And here he reaches what proves to be the core of the work—a classification of the sciences. The following classification, like that of Comte, is made on the basis of a progressive development.

"The formal sciences treat of characteristics belonging to all experiences, characteristics, consequently, that enter into every known phase of life, and so affect science in the broadest sense " (p. 55). Formal is not used here in the Kantian sense, for the formal sciences are just as experiential and empirical as the other two groups. On account of their breadth and the fact that they are the most general of all experiences, it is often forgotten that we are dealing with experiences at all and they are thought to be "native qualities of the mind, or apriori judgments." The main concept of the second group, the physical sciences, is energy—a concept which does not appear in the formal sciences. The inclusion of chemistry in this group is defended on the ground that the special science of physical chemistry, which has been developed as such during the last twenty years, forms a transitional science between physics and chemistry. Under the third group—the biological sciences—fall all the relations of living beings. Physiology is here defined as "the entire science dealing with non-psychic phenomena" (p. 56).

These sciences here classified are put into a regular hierarchy because the concepts that have been dealt with in the preceding sciences are used or