TRUTH

The accordance or conformity between what is asserted and what is, or the conformity of intellection with being. From the viewpoint of the intellect as consciously conformed to being, truth is called logical or epistemological; from the viewpoint of being as conformed to intellection, it is called ontological. This article deals first with the history of the notion of truth, then with truth as studied in epistemology, and finally with truth as studied in ontology.

HISTORY OF THE NOTION OF TRUTH

The historical development of the concept of truth may be divided into phases corresponding to the development of Greek, patristic and medieval, modern, and contemporary philosophy.

Greek origins. The problem of truth was implicitly treated at the dawn of Western philosophy (6th century b.c.), when men first sought principles that would explain the changing universe. It was explicitly treated by parmenides; rejecting the doctrine of heraclitus, he distinguished the world of sense as the domain of appearance, change, multiplicity, and falsity from the world of thought as the world of the stable, the one, and the true. The true, for Parmenides, is the object of thought or the intelligible, and the true or being is one. Multiplicity is appearance; it is the effect of the disintegrating influence of man's senses on being.

The sophists, holding that man cannot attain certainty and that the only truth he has is the contingent judgment of the senses, which differs from one individual to another, first posed the problem of necessary truth and of the subject-object relationship in the knowing process.

plato taught that on the occasion of sensation there is awakened in man a corresponding idea, which was dormant in the soul from its contemplation of the subsisting Ideas before its incarnation in the body. The Ideas are the universal, necessary, and immutable essences, the archetypes of the sensible reality that imitates and participates in them. The Ideas, existing in the intelligible world hierarchically under the supreme Idea of the Good, are more real than sensible reality. Necessary truth, therefore, is the conformity of man's thought to the Ideas. Contingent and changeable truth, or opinion, is the conformity of his knowledge to the sensible world.

For aristotle, truth is primarily in the judgment. The judgment is true when it attributes a predicate to, or denies it of, a subject, according to what reality itself demands. Truth then is the adequation of the intellect to reality. Judgment guarantees the necessary truth of the first principles, particularly that of contradiction, which are founded in being. The universal concept that functions in judgment is not had from an intuition of the subsisting Ideas, but is obtained by abstracting or dematerializing the formal notes of sensible reality (see abstraction). Aristotle even conceived God as Thought Thinking Itself (Meta. 1074b 15–1075a 11), and in this sense as subsisting Idea or Truth.

Patristic and Medieval thought. Christianity, as the revealed truth of God proposing the Second Person of the Holy Trinity as the Truth by whom all things that exist are made, opened up new vistas for philosophical speculation on the nature of truth. The greatest of the Church Fathers, St. augustine, inspired by Plato (as interpreted and synthesized with Aristotle by plotinus), made the idea of truth central in his philosophy (C. Boyer, L'Idée de vérité dans la philosophie de saint Augustin, 2nd ed. Paris 1947). Truth, as a property of knowledge, is the affirmation of that which is. Man knows immutable and eternal truths, e.g., the laws of number and essences, with certainty. By these truths he judges the sensible. These truths are not justified by sensible reality, but are a participation in man's intellect of the first and subsistent truth, which is God. Hence from necessary truth, such as two and two make four, one can prove the existence of God (Lib. arb. 2.8.20–24). Truth as applied to reality is the identity of the idea and reality. Reality is true when it fully verifies what is said of it, when it fully verifies the idea, and hence when it is the idea. Only God fully verifies the idea. He is truth. Finite beings are true insofar as they are imperfect imitations of the first Truth, of the Subsistent Idea, which is God.

St. thomas aquinas, who achieved the most perfect synthesis of Christian philosophy, unlike Aristotle treated truth explicitly as a transcendental property of being. Being as true is being as related to man's intellect (De ver. 1.1). Since being does not depend on man's intellect, the relation that truth adds to being is a relation of reason manifesting the intelligibility of being. This intelligibility is the dependence of being on its intelligent cause, God. Hence every being as intelligible presupposes its idea in the mind of God. God is identically subsisting Intellection and Being, or subsistent Truth. Knowing His essence as imitable, He forms the idea of every creature He can produce. Creating, God conforms to His intellect the reality produced, making it identically intelligible and existing (Summa theologiae 1a, 15). Man attains truth properly in the judgment. His direct judgment is the affirmation of the nature of sensible reality according to the norm of being.

Modern development. R. descartes, the father of modern philosophy, was concerned primarily with certitude as this is found in mathematics. Hence, for him, truth is that which man conceives in a clear and distinct idea. Clear and distinct concepts, which are also innate and intuitive, represent reality exactly as it is in itself. Reality and the conceptual are identical. The analytical laws of connection of concepts are laws of reality. This is the principle of rationalism. It led N. malebranche to ontologism, wherein man is proposed as having immediate intuition of the divine ideas. It led G. W. leibniz, complementing Cartesianism by dynamism, to his doctrine of a pre-established harmony among the active elements of the universe, which he conceived as incapable of acting on each other. Rationalism found its logical conclusion in the absolute monism of B. spinoza: there is only one substance, God, of whose infinite modes man knows only two, namely, extension and cognition.

Diametrically opposed to rationalism is empiricism, which, prepared for by the nominalism of william of ockham and by the scientific method of Francis bacon, appeared in England under T. hobbes, J. locke, and G. berkeley, but found its full expression in D. hume. With the exception of mathematics, which he saw as a logical analysis of identities, Hume reduced all valid knowledge to sense impressions and to images derived from sense impressions and associated by habit. Therefore, for him, the notions of causality, of substance, of soul, etc., are invalid. Hence truth for man is the conformity of his knowing to sense impressions. B. russell and logical positivists such as A. J. Ayer (1910–89) follow Hume in making sense verifiability the norm of truth for all factual statements.

For I. kant, who reacted against the extremes of rationalism and empiricism, truth is the conformity of thought to its object. The object of thought is not reality as it is in itself, however, but is the product of the a …