POINCARÉ, JULES-HENRI. - Mathematician and thinker, b. at Nancy (Meurthe-et-Moselle) on 29 April 1854, d. at Paris on 17 July 1912. He taught (1881) in the Faculty of Sciences at Paris; he was (1887) a member of the Académie des Sciences. His works of pure and applied mathematics are collected in more than 30 volumes; he wrote nearly 500 papers and several works of a general character: La science et l'hypothèse (Paris 1902), La valeur de la science (ibid. 1905), Science et méthode (ibid. 1909), Dernières pensées (posthumous, ibid. 1913).
P. affirms that "the only objective reality is the relations of things, from which universal harmony results"; these are not given "outside of a mind that conceives and feels them. But they are nevertheless objective because they are, will become and will remain common to all thinking beings" (La valeur de la science, p. 270). Science does not make things known but the relations between things: "Science is a system of relations" (op. cit., p. 265). To E. Le Roy, who affirmed that the scientist creates the scientific fact and that science has value only as a complex of rules of action, P. observes that science, insofar as it can foresee facts, must also have a theoretical value, and the scientist creates nothing in the fact except the language with which he states it (La valeur de la science, p. 213 ff.). As regards non-Euclidean geometries, P. admits that geometric axioms are conventions whose choice "is guided by experimental facts, but remains free and is limited only by the necessity of avoiding contradiction" (La science et l'hypothèse, p. 66).
In scientific research P. demands absolute freedom also with respect to religion: "There are men who forget their faith upon entering the experimental laboratory... And that is all that can be asked of them" (Dernières pensées, p. 331). Morality cannot be founded on metaphysics, nor on religion, nor on science, nor on utilitarian motives, but only on feeling (op. cit., p. 223 ff.).
Bibliography6 works
Roberto Masi