DUTY, an action that one is obligated to perform; a feeling, or sense, of obligation. In Judaism man's duties are determined by God's commandments. The entire biblical and rabbinic conception of man's role in the world is subsumed under the notion of mitzvah (meaning simultaneously "law," "commandment," "duty," and "merit"). The term ḥovah, meaning "obligation" or "duty," which came into use later, is used interchangeably with mitzvah. To perform a divine commandment is to fulfill one's duty, laẓet yedei ḥovah (Ber. 8b). The translator from the Arabic original into Hebrew of *Baḥya ibn Paquda's major work Ḥovot ha-Levavot ("Duties of the Hearts") used the term ḥovah as a synonym for commandment, and the term was taken up by other writers of *musar literature (for a discussion of the relationship between "mitzvah" and "ḥovah" see ET, vol. 12, S.V. ḥovah). Duty is the incentive to moral action, and a morality-based duty is evidently different from one that is based on pleasure. According to a talmudic dictum "Greater is he who performs an action because he is commanded than he who performs the same action without being commanded" (BK 38a). The pleasure derived from the performance of a commandment is irrelevant to its nature (cf. RH 28a "the commandments were not given to be enjoyed"), and conversely dislike of an action is no sufficient reason for abstention from it, cf. the saying of R. Eleazar b. Azariah: "Say not, 'I do not like to eat pork'… but say, 'I would like, but I will not for it is God's prohibition'" (Sifra 20:26; cf. Mak. 3:15). One should not perform an action in order to gain a reward, but because it is a divine commandment, and hence one's duty: "Be not like servants who work for the master on condition of receiving a reward…" (Avot 1:3).
The morality of an action is determined more by the motivation of the one who performs it than by its consequences: "You must do what is incumbent upon you; its success is up to God" (Ber. 10a). The notion of intention (kavvanah) is central in Jewish ethics: "Whether it be much or little, so long as the intention is pure" (Ber. 17a; Sif. Deut. 41); "God demands the heart" (Sanh. 106b). That is not to say that an action performed without the proper motivation is worthless. The fact that its results are beneficial does give it some worth. Moreover, through performing an action without the proper motivation, one may come to perform it with the proper motivation: "From doing [good] with an ulterior motive one may learn to do [good] for its own sake" (Pes. 50b; cf. Maim., Yad, Teshuvah, 10:5).
The major problem in modern Jewish thought in connection with the concept of duty is posed by the Kantian notion of autonomy, according to which an action to be moral must be motivated by a sense of duty, and must be autonomous (I. *Kant, Fundamental Principles of Ethics, trans. by T.K. Abbott (194610), 31ff.). This appears to conflict with the traditional Jewish notion that the law is given by God, that is, that it is the product of a heteronomous legislator. Moritz *Lazarus in his Ethik des Judentums (1898, 1911; The Ethics of Judaism, trans. by H. Szold, 1900) attempts to show that rabbinic ethics are based on the same principles as Kantian ethics, the basic underlying principle of both being the principle of autonomy (ibid., 1 (1898), no. 90–105). In so doing he somewhat distorts the Kantian notion of autonomy. Hermann *Cohen, in Die Religion der Vernunft aus den Quellen des Judentums, in his attempt to deal with the problem of heteronomy and autonomy, interprets mitzvah to mean both "law" and "duty,"
J. Heinemann, Ta'amei ha-Mitzvot be-Sifrut Yisrael, 2 (1956), index S.V. heteronomiyyut.