bears eternal witness to this fact. The only alternative, therefore, is to start from Mind and endeavor to work back. This is the endeavor of pluralism. The pluralistic hypothesis is briefly as follows: "Reality comprises selves (i.e., active subjects of experience) alone, differing simply in degree of mentality, though the diversity is indefinitely various." Experience, then, consists in action and reaction between self and other selves, described by Professor James Ward in the expressive phrase "mutuum commercium." The meaning of 'activity' is considered to be fundamentally realized by everybody, but to this point we shall return.
The comparative hopes of a solution of the problems of philosophy held out respectively by Pluralism and by any form of Materialism, are sufficiently indicated by comparing the start made from the existence of selves as a basis, with that based on the existence of ultimate material particles—atoms, corpuscles, electrons, or whatever they may be considered to be. We know that some selves exist.[1] Strictly, each of us knows that one self exists; but, as we have seen, if we are to philosophize to any extent worthy of the name, we must take a further step and assume the existence of other selves, nor can this assumption in any way be demonstrated to be false. It is therefore justifiable to make it. On the other hand, even should the material particles of physics actually exist (and this seems very doubtful), we could not know of their existence. The scientific method demonstrates this sufficiently. Moreover, if, as that method shows to be extremely probable, the entities of physics are simply constructions of sense-data, we cannot conceive a self in terms of these entities; for evidently a self cannot simply be a logical function of sense-data. To sense-data we apply the term 'phenomenal,' i.e., 'presented to a subject,' thereby implying that we realize the fundamental distinction in kind between the subject and the sense-data or phenomena which it perceives. It is impossible, therefore, to imagine that we ourselves can be analyzed into sense-data; in fact, the supposition involves a contradiction in terms, for sense-data are 'given' or 'presented'
- ↑ See Section V below.
