17. Intuition, Demonstration, Judgment.
INTUITIVE KNOWLEDGE is the perception of the CERTAIN agreement or disagreement of two ideas immediately compared together.
RATIONAL KNOWLEDGE is the perception of the CERTAIN agreement or disagreement of any two ideas, by the intervention of one or more other ideas.
JUDGMENT is the thinking or taking two ideas to agree or disagree, by the intervention of one or more ideas, whose certain agreement or disagreement with them it does not perceive, but hath observed to be FREQUENT and USUAL.
18. Consequences of Words, and Consequences of Ideas.
Though the deducing one proposition from another, or making inferences in WORDS, be a great part of reason, and that which it is usually employed about; yet the principal act of ratiocination is THE FINDING THE AGREEMENT OR DISAGREEMENT OF TWO IDEAS ONE WITH ANOTHER, BY THE INTERVENTION OF A THIRD. As a man, by a yard, finds two houses to be of the same length, which could not be brought together to measure their equality by juxta-position. Words have their consequences, as the signs of such ideas: and things agree or disagree, as really they are; but we observe it only by our ideas.
19. Four sorts of Arguments.
Before we quit this subject, it may be worth our while a little to reflect on FOUR SORTS OF ARGUMENTS, that men, in their reasonings with others, do ordinarily make use of to prevail on their assent; or at least so to awe them as to silence their opposition.
First, Argumentum ad verecundiam.
I. The first is, to allege the opinions of men, whose parts, learning, eminency, power, or some other cause has gained a name, and settled their reputation in the common esteem with some kind of authority. When men are established in any kind of dignity, it is thought a breach of modesty for others to derogate any way from it, and question the authority of men who are in possession of it. This is apt to be censured, as carrying with it too much pride, when a man does not readily yield to the determination of approved authors, which is wont to be received with respect and submission by others: and it is looked upon as insolence, for a man to set up and adhere to his own opinion against the current stream of antiquity; or to put it in the balance against that of some learned doctor, or otherwise approved writer. Whoever backs his tenets with such authorities, thinks he ought thereby to carry the cause, and is ready to style it impudence in any one who shall stand out against them. This I think may be called ARGUMENTUM AD VERECUNDIAM.