Sufficient Reason (Principle of)

SUFFICIENT REASON (PRINCIPLE OF). - It expresses the "rationality of the real" insofar as everything, both in the realm of being and in that of becoming, obtains its ontological determination and its change of state by virtue of a sufficient reason in the sense of an adequate foundation and justification.

The principle owes its modern formulation to Leibniz (v.). Together with that of contradiction (v.), the principle of sufficient reason underlies our reasonings as a criterion of what must be judged true or false: according to it "one judges it impossible that any fact be true or exist, and any proposition be true, unless there is a sufficient reason why it is so and not otherwise" (Monadology, § 32; Italian trans., Bari 1912, p. 220. Cf. also: Ep. V. ad Clarke; Essais de théodicée, § 44, where it is placed at the foundation of optimism [v.]; Nouveaux essais, II, 21, § 13 ... "que rien n'arrive sans raison"). The principle had its systematic development in the philosophy of C. Wolff (v.) with rigorous coherence according to the formula that was very successful in Enlightenment rationalism: "Nihil est sine ratione sufficiente cur potius sit quam non sit, hoc est, si aliquid esse ponitur, ponendum etiam est aliquid, unde intelligitur, cur idem potius sit quam non sit" (Philosophia prima sive ontologica, § 70, Frankfurt and Leipzig 1736, p. 47. In §§ 71-80 the application to the various problems of the sciences and of philosophy follows). Crusius attacked the Leibniz-Wolff conception of sufficient reason in the work: De usu et limitibus principii rationis determinantis, vulgo sufficientis (Leipzig 1743, esp. §§ V-XVI). The principle was instead defended by Schopenhauer (v.) in the early work: Ueber die vierfache Wurzel des Satzes vom zureichenden Grunde, § 14. It also found favor among some Neo-Scholastics (J. Geyser, R. Garrigou-Lagrange), who consider it the proximate foundation of the principle of cause (v.).

Cernello Fabro