SOLIDARIETÀ. — A term deriving from Roman law, where the joint obligation, or in solidum, denoted an obligation involving a plurality of parties (creditors or debtors) and an identical and single object, whereby each of the several debtors is bound to perform the entire obligation, or each of the several creditors is entitled to the entire performance; but, on the other hand, only one of the debtors pays or answers for all, and conversely only one of the creditors demands or obtains satisfaction for all (P. Bonfante, Istituzioni di diritto romano, 5th ed., Milan 1912, p. 362).
This meaning persists in modern civil codes (cf. Italian Civil Code, art. 1184 ff.) and in moral theology (v. OBBLIGAZIONE; RESTAUBAZIONE). In primitive criminal law s. was understood in the sense of collective responsibility, whereby the members of a group were liable to vengeance for a crime committed by only one of them (cf. G. Glotz, op. cit. in bibl.). This juridical meaning of s. was broadened in the 19th century to indicate natural s., founded on physical and biological laws (cf. Cl. Bernard, Introduction à l'étude de la médecine expérimentale, II, Paris 1865, p. 3), and consequently, according to positivistic determinism, social s. For A.
Comte, s. indicates either the intrinsic and total dependence of every human being on preceding generations (Système de polit. posit., Disc. Prélim., I, Paris 1851, p. 364) or on the present social situation (ibid., pp. 364-65; III, 1, p. 71). With E. Durkheim, the concept of social s. became fundamental for the French sociological school. In his Division du travail social (1893) he distinguishes a double social s.: mechanical and organic. The former is founded on the similarities and uniformity of feelings, ideas, customs, and beliefs, without any manifestation of individual originality, and gives rise to repressive law; with the introduction and progress of the division of labor, s. becomes increasingly organic, that is, the coordination and subordination of differentiated and hierarchized elements, as among the organs of a living body, giving rise to a cooperative law based no longer on repression but on restitution (cf. ibid., I, 2-4). His thought was developed especially by C. Bouglé (Le solidarisme, Paris 1924).
Humanitarianism has attempted to make s. the fundamental virtue of moral life, replacing justice and charity with it (P. Leroux, De l'Humanité, de son principe et de son avenir, ibid. 1840). Moral solidarism has its foremost representative in L. Bourgeois (La solidarité, ibid. 1879): the fact of social s. shows that everything a person possesses or is capable of understanding or doing is the fruit of the labor of society as a whole, present and past; this is a debt that the person must repay by devoting himself entirely to placing his activity at the service of society, accepting all the sacrifices that may result from this. Moral good is therefore identified with the demands of s.; and moral duties impose upon us the obligation always to keep before our eyes the repercussions of our actions in collective life. To explain the transition from s. as a fact to s. as a duty, Bourgeois appeals to the psychological instinct of the need for justice that exists in every conscience.
The existence of a natural s. among all beings and of a social s. among all human beings is an indisputable fact: nevertheless, it is not the cause of social life, but merely a conditioning factor of personal activity. Moral s. must be distinguished as «fact» and as «duty». As a fact, it rightly emphasizes the good and evil consequences for society resulting from the good or evil activity of each individual person, so that the value of the community depends on the moral value of each individual. As a duty, it is nothing other than an ambiguous term expressing the duty of justice and friendship, which lies at the basis of all the social duties of the person and finds its ultimate foundation in the eternal divine law (v. OBBLIGAZIONE). Every person receives from God the natural vocation to cooperate in the good of his brothers according to the various forms of sociality and according to his particular task in each of them (v. STATO, OBBLIGHI DEL PROPRIO): society is the collaboration of persons in jointly realizing particular human goods with a view to the eternal attainment of the supreme good. Given the historical character inherent in the concept of society, the activity of every person comes to have the value of intimate collaboration in the human good not only on the horizontal plane of existing society, but also on the vertical plane of historical society.
The term s. is also used today in dogmatic theology with regard to particular questions: s. in Adam, in Jesus Christ, among human beings; v.: COMUNIONE DEI SANTI; PECCATO ORIGINALE; REDENZIONE; for the same concept developed in moral theology, v.: COOPERAZIONE; GIUSTIZIA; RESTITUZIONE.