Reason

REASON. — A philosophical term which, especially in the sense of faculty (v.), has had in the history of Western thought a multiplicity of meanings that have often generated equivocations and misunderstandings. Probably the term ratio derives from ratus, the participle of reor (to believe, to think), and before its properly philosophical use it meant calculation, relation. Ratio corresponds both to νοῦς (Plato) and to λόγος, with this difference: νοῦς is properly the faculty or the activity, λόγος is the content of νοῦς (the truth) or that which reason constructs (discourse, the set of relations, etc.). It is appropriate to distinguish the two fundamental meanings of the term: reason as faculty (Vernunft) and reason as object of knowledge (Grund).

I. REASON AS A FACULTY

The two terms νοῦς and λόγος together adequately express the sense of r. as a discursive or ratiocinative faculty, capable of formulating proofs, of combining concepts and propositions, of giving demonstrations. In this function it is considered as proper to man (who, according to the famous Aristotelian expression, is ζῶον λογικόν), as St. Thomas says (In III Sent., dist. 25, q. 1, a. 1). "et Deo non convenit nec Angelis". In this sense it is distinguished from the intellect (v.), which is intuitive activity, apprehensive of being and capable of grasping first principles and the primary necessary truths of thought and of life. These are not two faculties, as St. Augustine and St. Thomas say in agreement. Indeed, for St. Augustine, ratio and intellectus (or intelligentia) inhere naturaliter in the mens (De civ. Dei, XI, ch. 2); the intellectus is superior to the ratio (In Joann. Evang., tract. XV, 4, 19; and St. Thomas, Sum. Theol., 242⁶⁰, q. 45, 5 ad 3), insofar as it is inner sight (with which the mens perceives the truth, which the divine light discloses to it), the principle of understanding and the true eye of the soul (De ordine, II, ch. 2, n. 5; ch. 9, n. 26).

The r., on the other hand, is aspectus animi, an organ of inquiry that discerns (analysis) and connects (synthesis), that is, the discursive faculty that applies itself to the sense that is inferior to it and to sensible things in order to judge them (De vera relig., ch. 29, n. 30). For Spinoza (v.) too the r. is inferior to intuitive science: the former makes us see things sub quadam aeternitatis specie, the latter sub specie aeternitatis. Kant (v.) distinguishes between r. (Vernunft) — the faculty that makes us know the principles of a priori knowledge — and pure r., the faculty that contains the principles that allow us to know something exclusively a priori (Crit. of Pure R., Introduction, § VII); between theoretical or speculative r., that which applies itself to pure knowing and which founds and builds science, and practical r., that which contains the a priori principle of action or the rule of morality. Moreover Kant understands the term r. in the special sense of the higher faculty of the three metaphysical ideas of the soul, the world and God (Cr. of Pure R., Transcendental Dialectic, I, 1, sec. 1⁸). In this sense the r. (Vernunft) is not opposed to experience (as in the previous case), but is distinguished from and opposed to the intellect (Verstand). Rosmini (v.) too, going back to St. Augustine and in order to combat the Kantian transcendental, distinguishes between r. and intellect or light of the r.: the former is "the faculty of applying the idea of being" which is intuited by the intellect (Principi di sc. morale, ch. 1, art. 1). The post-Kantians made of the r. the absolute, intuitive of all the real that identifies itself with it: for Jacobi (v.) it is the faculty of grasping the supersensible; for Schelling (v.) "it is the absolute" (Darstellung meines Syst. der Philos., in Sämtl. Werke, VI, p. 115); for Hegel (v.) it is "the certainty of being all reality"; the universality and objectivity in itself and for itself of Self-consciousness (Encicl., § 437).

Still in the sense of faculty, r. means judging well or rightly, that is, making good use of the rules of logic (v.), just as it also indicates, in modern rationalism and in Kant, the system of a priori principles, not dependent on experience; and finally it is used in opposition to faith (v.) and to revealed and supra-rational truth (for these last three senses v. RAZIONALISMO).

II. REASON AS AN OBJECT OF KNOWLEDGE

It is that which explains something in a twofold sense: ontological, as, for example, "reason for being," the "why" that explains and demonstrates the reason of a thing, the final cause and the formal cause; and epistemological, that is, the argument by which an affirmation is supported and justified. In the language of the Scholastics, the ratio of a thing is its essence (ratio intellecta is the same concept considered objectively). It can also be used in the normative sense of justification: for example, in the expression "I have my reasons for acting or thinking thus," that is, the legitimate motives for acting and affirming thus and not otherwise. In this sense the reason of a proposition or of a thesis is that which justifies it and demonstrates it to be objectively valid. Finally, the expression "being of reason" is that which has an objective existence only in the mind (without this excluding that it may have a real foundation), as, for example, relations, negations, etc.

Contemporary philosophy has strongly criticized reason as an object of knowledge both in the ontological sense (denial of the final and formal cause) and in the epistemological sense: there are no arguments to demonstrate an affirmation necessarily, inasmuch as there exist only "hypotheses" that are accepted (one or the other) according as they prove more or less suited to a given historical or practical situation (v. the entries IRRAZIONALISMO; NEOPOSITIVISMO; PRAGMATISMO, etc.).

Michele Federico Sciacca