No. 3.] SCIENTIFIC METHOD IN PHILOSOPHY. 271 ciality. That fundamental characteristic of the object of experience which is commonly termed 'continuity,' is really unity—unity in space and time. This consideration alone is sufficient to show that any theory which purports to give a final answer to any of the problems of the Universe in terms of such things as sense-data, may be ruled out at once. On the other hand, the unity of the object implies the unity of the subject, for this is its ground. It thus emphasizes the fact that selves are single space-time entities that may be taken as true units in terms of which to express our explanation of the objective facts of existence.
This idea of the self as a unity which, in its completeness, transcends space and time, though for most purposes we conceive it as developing in space and time, is the conceptual representation of something realized concretely in actual experience, namely, the persistence of our identity through change and development. This reconciliation in the self of the principles of permanence and change provides us with a concrete example of that which we endeavor to conceive when we talk of 'substances.' It is impossible to formulate the reconciliation adequately in words, but it is there, and we realize its existence and its nature. We cannot rest content with regarding the object of experience as mere change (whatever that may be) based on no elements of permanence, so that we come to look upon experience as interaction between self and other selves, following the pluralistic hypothesis. Accordingly, the attributes of these selves or substances are their modes of activity.
In many cases this activity seems to lack spontaneity and to conform more or less completely to general laws, being due, as we suppose, to selves of extremely inferior mentality, and so, for the most part, the slaves of habit in their reactions. In many other cases the activity is only completely explicable with reference to the end which it achieves. Possibly we might be able to describe the activity completely in terms of the ordinary objective conceptions of physical science. This alone, however, leaves us far from satisfied. We can no more be content with it than we could be content with a mere description of the acts of other people accompanied by no statement nor understanding of their
