and a temporal reference. Hence there will be a set of propositions concerning the individual which will be true once for all. Regarding the propositions as particular values of certain prepositional functions, the particular value of the argument of these functions is the individual considered. Since the propositions, however, are not limited as to their truth-value by space nor time, the particular value of the argument cannot be dependent upon space nor time. Thus the individual is a space-time unity.
From this conceptual standpoint, such notions as 'process' and 'development' lose nothing of their meaning nor value, but, like all concepts which refer to matters-of-fact, their inadequacy leads to the difficulties we have been analyzing. Yet although the solution of the problem of identity and change is attended by such difficulty when looked at from an abstract point of view, the concrete solution is more easily realized. The self combines, in a particularly complete way, the principles of identity and change. In spite of change, I realize myself to be the same individual that I once was. Even if we cannot formulate in words, on account of its uniqueness, the exact nature of this reconciliation of change and permanence in the subject of experience, it is, to say the least, almost as satisfactory to realize its existence. This being so, we are encouraged to apply the pluralistic hypothesis by regarding the permanent ground of the changing flux of experience as consisting in individual subjects.
Before considering the notion of 'attribute,' it may be of interest to make a short digression at this point, by referring back to Minkowski's conception of a space-time world and its bearing on philosophy. The conception arose in the first instance out of difficulties similar to those we meet with in analyzing change. Recent researches in physical science have brought to the fore, with increasing insistence, the question as to what meaning, if any, is to be attached to such notions as absolute velocity and absolute position. The controversies to which these problems gave rise culminated in the enunciation of the well-known Principle of Relativity. There are several ways of stating the latter, but each amounts to this: 'Different descriptions of the same system will be given by different observers.' A description
