logic is most conspicuous and significant in reference to the theory of classification. Modern logic does not conceive of its concepts as water-tight compartments. They possess no inevitableness of solidity about them. They do not form a closed system. They are mobile, fluid, plastic. They take a form which is ever changing with enlarging experience. The modern theory of classification today provides for limiting cases, for the arrangement of its terms in a serial order of progression, for the merging of one class into another, for a wide range of variations about a type, for the appearance even of mutations which are unexpected and unannounced. New forms are not discarded because there is no place for them, but they are given a place which they themselves compel. Every system of classifying vital phenomena is a living system, subject to constant change and adjustment. It is after this manner that Darwin built up his body of knowledge, a body having the spirit of life, and not a mass of dead immobile elements. However, on the other hand, a study of particular instances without conceptual knowledge as an instrument of interpretation and of direction would prove a wholly confused and futile undertaking. Bateson has given a very illuminating statement concerning the method of investigating the particular phenomenon: "To those who have made no study of heredity, it sometimes appears that the question of the effect of conditions in causing variations is one which we should immediately investigate, but a little thought will show that before any critical inquiry into such possibilities can be attempted, a knowledge of the working of heredity under conditions as far as possible uniform must be obtained."[1] He emphasizes here the necessity of having some knowledge of the law of uniform behavior in general, in order to interpret the variations which may occur in particular instances. Variations have meaning only when the type has been established, and is duly recognized as such.
Höffding in his essay on Evolution and Modern Philosophy insists that "evolutionism and systematism are opposing tendencies which can never be absolutely harmonised one with the other. Evolution may at any time break some form which the system- monger regards as finally established." And he quotes Darwin
- ↑ Darwin Centenary Volume, p. 95.
