Page:Philosophical Review Volume 24.djvu/439

No. 4.] said enough to show that his system would have diverged widely from Locke's. The difference between their systems of ethics would have been identical with that between their theories of mathematics. For Locke, geometry is a pure science, dealing only with relations of universal ideas, abstracted from all concrete experience. On the other hand Berkeley holds that geometry is essentially practical. The Principles cut away the speculative parts of mathematics, leaving only what is practical and useful. Geometry deals throughout with concrete existence. In a precisely similar way Berkeley's theory of ethics differs from Locke's. Ethics is for Locke a pure science which omits all question of the realization of abstract ideas in the concrete matter-of-fact of moral experience. But Berkeley's view is very different. Ethics is an applied or practical science. It does not consider relations of ideas by means of intervening ideas. Berkeley holds that ethics is a demonstrative science which, like mathematics, deals with words or signs and not with ideas. We can have no certainty about ideas, as Locke supposed. It is possible to reason about ideas, but demonstration can be only verbal. "To demonstrate morality it seems one need only make a dictionary of words, and see which included which." Words are signs and the reason why demonstration is possible and easy with regard to signs is that they are arbitrary. Hence the demonstrability of mathematics, which deals solely with signs. Further, Berkeley believed that Locke's abstract ideas do not exist either in mathematics or in ethics. An abstract idea of triangle is impossible. Equally impossible is an abstract idea of justice. On Berkeley's theory, we reason always about a particular, which stands for all other particulars of the same kind.