that cannot be established by any middle term, or, in other words, by any syllogistic reasoning. The axioms of Euclid may give us a specimen of such principles, but, according to Aristotle, each science had its own “primary universal, and immediate principles;” these principles, we are distinctly told, are not innate, but the source of them is the Nous or Reason, which (as we have seen) attains them intuitively, when sufficiently advised, so to speak, by a course of inductive observation. Again, Aristotle brings out here his opposition to Plato’s theory of Ideas: he says, that it is not necessary for Science that the Ideas of things should have a separate existence, but only that universal ideas, or genera, should be capable of being predicated of many individuals. This view seems to correspond with what, in modern times, has been called Conceptualism, and which is a compromise between Nominalism and Realism.
These, however, are metaphysical distinctions. Another point more closely belonging to the Logic of Science is brought out against Plato—namely, the separateness of the Sciences, which follows from each Science having its own appropriate principles. Plato conceived, or appeared to do so, that from the principles of Philosophy (i.e., Metaphysics), right doctrines of Ethics and Politics could be deduced. Hence he said, “It will never be well with the State till the kings are philosophers, or the philosophers kings.” Aristotle, on the other hand, considered the speculative conception of the good, as entertained by a metaphysician, to be quite distinct from the practical concep-
