CHAPTER II.
TRUTHS AND CONCEPTIONS FURNISHED BY THIS FACULTY
§ I.—Primary Truths.
Primary Truths and Primary Ideas as distinguished.—The faculty in question may be regarded as the source of primary beliefs, truths, cognitions, intuitively perceived, and also of primary and original conceptions, notions, ideas, also intuitively conceived.
The difference between a conception or idea, and a belief or truth, is obvious. The notion of existence, and the knowledge or belief that I, myself, exist, are clearly distinguishable. The idea of cause, and the conviction that every event has a cause, are distinct mental states. The one is a primitive and intuitive conception, the other a primitive and intuitive truth. Every primary truth involves a primitive and original conception.
Existence of first Truths.—All science and all reasoning depend ultimately on certain first truths or principles, not learned by experience, but prior to it, the evidence and certainty of which lie back of all reasoning and all experience. Take away these elementary truths, and neither science nor reasoning are longer possible, for want of a beginning and foundation. Every proposition which carries evidence with it, either contains that evidence in itself, or derives it from some other proposition on which it depends. And the same is true of this other proposition, and so on forever, until we come, at last, to some proposition which depends on no other, but is self-evident, a first truth or principle. Whence come these first principles? Not of course from experience, for they are involved in and essential to all experience. They are native or à priori convictions of the mind, instinctive and intuitive judgments.
Existence of first Truths admitted.—The existence of first truths or principles, as the basis of all acquired knowledge, has been very generally admitted by philosophers. They have designated these elementary principles, however, by widely different appellations. By some, they have been termed instinctive beliefs, cognitions, judgments, etc., an appellation mentioned by Hamilton as employed by a very great number of writers from Cicero downward, including, among the rest, Scaliger, Bacon, Descartes, Pascal, Leibnitz, Hume, Reid, Stewart, Jacobi. Others, again, have termed them à priori or transcendental principles, cognitions, judgments, etc., as being prior to experience, and transcending the knowledge derived from sense. So Kant and his school termed them. By the Scotch writers they have been termed, also, principles of common sense, in place of which expression Stewart prefers the title, fundamental laws of human belief.
Criteria of primary Truths.—It becomes an important inquiry, in what manner we may recognize and distinguish first truths from all others. Besides common consent, or universality of belief on the part of those who have arrived at years of discretion, Buffier relies, also, upon the following, as criteria of first principles; that they are such truths as can neither be defended nor attacked by any propositions, either more manifest or more certain than themselves; and that their practical influence extends even to those who would deny them. Reid gives, among other criteria, the following: consent of ages and nations; the absurdity of the opposite; early appearance in the mind, prior to education and reasoning; practical necessity to the conduct and concerns of life. Hamilton gives the following as tests or criteria of first truths: 1. Incomprehensibilty.—We comprehend that the thing is, but not how or why it is. 2. Simplicity.—If the cognition or belief can be resolved into several cognitions or beliefs, it is complex, and so, no longer original. 3. Necessity, and consequent universality.—If necessary, it is universal, and if absolutely universal, then it must be necessary. 4. Comparative evidence and certainty.
Summary of Criteria.—The following may be regarded as a summary of the more important criteria by which to distinguish primary truths from all others.