Page:Philosophical Review Volume 27.djvu/263

No. 3.] it is correct to say that we are the victims of illusion. Yet, however that may be, the fact remains.

Returning to the new realists, we find then that they deny the validity of the concept of efficient causality. They maintain that the only meaning which causality can have is that which we have seen it possesses in descriptive science, namely, that in objective experience certain essentially similar sequences recur, which fact is expressed in a number of propositions (one for each set of similar sequences) termed 'causal laws.' This they consider is all that can be said on the subject. As an example of a causal law the law of gravitation is frequently cited. The latter contains no reference to 'cause' or 'effect.' The expression of the law as applied to a material system, simply takes the form of certain differential equations. From these it follows that the configuration of the system at any given instant is a function of that instant, and of the configuration at two given instants. This is true enough, but the fact remains that such differential equations, and the function which is their integral, are purely descriptive. They contain no hint as to 'how' and 'wherefore.' They simply tell us what does occur, without suggestions why it occurs. Moreover, there is still the question as to what determines the particular form of the equations from which the configuration at any instant can be deduced. It is not determined by logic, for logic and mathematics can give no answer to the question. As already suggested, the ground of the motions of such a system lies in activity. The particular nature of the motion, with its corresponding typical descriptive function, is determined by the particular type of activity of the agents concerned. The fact that our differential equations are shown by experience to hold for past and future as well as for present, simply means that the activities of certain individuals are sufficiently habitual to admit almost completely of description in general terms. We have seen that the introduction of the notion of active subjects does more than shift the descriptive formula one step further back, for it provides an explanation as opposed to a mere description.