Page:Mind (New Series) Volume 8.djvu/496

 482 FEEDINAND TONNIES : but partly upon a false assumption as to the aim and value of the whole mode of thought, an assumption which in- deed has been defended most keenly by the most decided adherents to that thought. It depends upon a just insight, for the view that mechanical causality is completely " con- ceivable," that, in other words, the necessity of the law of persistence upon which it is based may be known a priori, is the last refuge of the fancy that the "universe" is and must be somehow " explainable," in the sense of the state- ment that it has been " created " by a God, i.e. by a spirit ; behind the fancy lies the belief in magical effects. This view has been exposed most clearly and fundamentally by David Hume ; but, long before, its refutation and subjuga- tion had been contained in the deepest and most radical system of thought which was brought against Christian Aristotelianism, in the system of Spinoza. For Spinoza's proposition, ratio = causa, which is ordinarily interpreted as an expression of the most extreme opposition to Hume, of Rationalism in its strictest form, is really something quite different. What he means to say is, there is no " causa," no " real " and therefore " efficient " causes, there is nothing but " ground of knowledge " ; but this is the necessary form of our thought, in so far as it forms universal concepts, in which particular concepts are contained, and from which they follow. Hence in this sense the universal concept, the common ground of knowledge or the "cause" of all phenomena, is that Infinite (i.e. that which cannot be expressed by any unit of quantity or number), which Spinoza defines as substance or nature, and which the natural science of to-day, differing only in the name, calls self-maintaining energy. But the opposition depends on the other hand upon a false assumption ; the assumption that the reduction of the forms of energy to mechanical motion must, or indeed could, mean that by it mechanical motion would be established as the more real or as the only real. This is certainly the uncritical view of most naturalists. The real question can only be, whether an external world, consisting of like units (centres of force), which work mechanically upon each other and thereby change their mutual positions, is for our thought the ultimate numerator to which a mathematical interpretation of phenomena must refer all magnitudes and their changes, if it is to proceed consistently. This world is not comprehensible in the sense that we are able to see the effect of a direct impulse as necessary, but in the sense that if motion can be thought of as a quantity as Galileo has taught us to think then it is capable of