Part Three

Origin of the First Principles of Reasoning

CHAPTER 3

The nature of scientific principles in general

570. We have seen that the principles of knowledge, contradiction, substance and cause are only the idea of being in its application, that is, the law governing its application expressed in a proposition.
This observation opens the way to understanding the nature of all the principles of reasoning which in general are only ideas used for making judgments.
The application of these ideas can always be conceived as a judgment, and expressed in a proposition.
The proposition serves as a norm for forming a series of more particular judgments, virtually contained in the first, most general judgment to which they are subordinate. This first judgment is a principle relative to others deduced from it. Such deduction is called reasoning.

571. For example, the idea of justice becomes the principle of ethics when we reason and systematise its applications; the idea of beauty becomes the principle of aesthetics when it is considered as directing, regulating and indeed originating all our reasoning about what is beautiful.
Hence the definition of beauty is only the proposition resulting from an application of the idea of being, and is the first principle of any reasoning about what is beautiful.

572. Generally speaking, then, the essence of things is the principle of our reasoning about them.

573. The principle of each science therefore is the definition that expresses the essential idea of the subject of that science. From this truth comes the art of classifying the sciences correctly and reducing them to unity. They are no longer mere collections of disconnected information but well ordered treatises, each regulated by a single principle from which other truths are clearly seen to originate as rays of light from a common source.