FIDELITY. — It derives from *fides* and has the sense of keeping faith. It is a virtue very closely related to truthfulness, indeed one might say it is part of it, and moralists consistently define it as the virtue that induces a person to fulfill with due sincerity and exactness what he has said and promised. Although closely related, fidelity is distinct from truthfulness. The latter refers solely to the perfect equation between what one thinks and what one manifests externally through words, signs, or deeds, without regard to the factor of promise, which may or may not be present, whereas it is indispensable in fidelity. It nevertheless agrees with truthfulness in that fidelity also requires a perfect equation between the promise made and the fulfillment of what is promised. Therefore, truthfulness can be conceived without fidelity, but fidelity cannot be conceived without truthfulness. From what has been said, it follows that fidelity is intimately united to promise (q.v.), of which it then shares the fate with regard to the obligations it produces. Given this particular, intimate relationship between fidelity and promise, the dependence of the former on the latter, various kinds of fidelity may be distinguished, all of which agree in the factor of equality between what is promised and what is done, but differ noticeably according to the different kinds of promises.
Now there is a promise that is proper to every contract, indeed it is natural to it and inseparable from it; from this promise arises an obligation of commutative justice, and it is obvious that in this case the obligation of fidelity is perfectly identical with the obligation of justice and therefore they constitute one and the same thing. This occurs not only in cases of explicit and formal contracts, such as a sale, an exchange, marriage—where the term conjugal fidelity is well known, a most grave duty of justice of one spouse toward the other—but also in those implicit cases constituted by quasi-contracts (q.v.) taken in the strict sense, as occurs in the various professions that have direct or indirect dealings with others: the professional obligations of physicians, notaries, magistrates, parish priests, etc., fulfilled with due care, constitute a true virtue of professional fidelity. In all these cases, we are in the realm of justice.
A certain obligation of fidelity also arises in other analogous quasi-contractual cases, though not clothed with the same characteristics. In these cases, however, the obligation of fidelity does not, at least ordinarily, constitute a burden of commutative justice, nor, if violated, does it impose particular duties of repairing damages caused by infidelity. Thus, any assignment or task, taken in a very broad sense, if fulfilled with exactness and adequate care, is said to be fulfilled with fidelity. It is not difficult, however, for an obligation of fidelity arising from strict commutative justice to emerge in these cases as well.
In both the case of a true contract or quasi-contract and in these latter cases, fidelity is not taken in its proper, specific sense. Moralists indeed admit that the term fidelity precisely indicates an obligation different from that of commutative justice. It is in this latter sense, which has then come into common usage among all peoples, that the notion of fidelity is perfectly realized, taken precisely as the fulfillment of what has been spontaneously promised out of liberality and not as the performance of a service received. This is the case of a pure and simple promise, from which the obligation of justice is excluded either by the express will of the person or by the very nature of things. It must therefore be held that fidelity, rather than an obligation of justice, indicates an obligation that is merely moral and of conscience to make what has been promised coincide with what is then to be put into practice.
Even with regard to the obligation of conscience in fulfilling what has been promised, the foregoing observations must be kept in mind. Therefore, whereas in the first case (contracts, quasi-contracts) there is always an obligation of justice to adhere to what has been promised or owed, and in the second (cases analogous to the first) such an obligation can very easily follow; in the last (a mere promise, pure and simple), apart from very rare exceptions—due more to the intervention of external circumstances than to the nature of the promise itself—the obligation to adhere to what has been promised is always one merely of fidelity (excluding that of justice). A serious consequence that greatly distances fidelity is that whereas in fidelity that coincides with the virtue of commutative justice the obligation that arises is grave or light according to whether the matter is grave or light, in simple fidelity, i.e., fidelity in its most technical sense, it is always light; and therefore, whereas in the first two cases there is an obligation to repair damages generally arising from infidelity, such a burden exists in the last case even if the infidelity to the promise is trivial and in no way motivated.
The reason for this assertion, so grave in appearance, lies in the fact that the person to whom the promise is made has no strict right to the thing promised, since it belongs to the one who promises, nor does the transmission of the right occur solely by virtue of the promise having been made. This is proven by the fact that generally the one who promises intends only to bind himself lightly; and it is he alone who can give rise to one or the other obligation according to what he intends; and secondly by the fact that a grave obligation is not required by necessity for the common or social good, indeed this is greatly promoted by the light obligation alone. It is obvious indeed that if for every purely liberal promise a grave obligation of conscience were to arise, many would refrain from making it, especially those who, being more delicate of conscience, would practically be deterred even if burdened only with a light obligation.