in Louisiana.66 Because of the confusion which such usage can create, it is suggested that the terms unilateral/bilateral should be restricted to describing the number of parties constituting the obligation (the juridical act sense), and the terms gratuitous/onerous to describe the number of parties having duties under the obligation (as suggested earlier).

Jurisdictional policy reasons aside, there is no theoretical reason why promises may not be unilateral in any of the three senses mentioned above. Going further, ought unilaterality (in either sense) to be a requirement of a statement being a promise? Going against such a suggestion, it is certainly true that, in ordinary speech, one hears people talking about an exchange of promises, or mutual promises, particularly in Common law jurisdictions (which commonly still conceive of the law of contract in this way). Naturally, if a promissory view of contract were ever to be abandoned, there would be less need for the law to continue to conceive of promise in a way which encompassed bilateral as well as unilateral promises. One might then maintain a ‘purer’ doctrine of promise which excluded from the definition anything other than unilateral promises; mutual contracts would require description by reference to some concept other than an exchange of promises. There is no indication that such a development is imminent, however, and therefore in this work the concept of a promise will be drawn widely enough to continue to allow both unilateral as well as bilateral (or multilateral) commitments within the definition of that term. What sense of the word is meant at any particular point of the discussion should be evident from the context.

3.  Acts having some similarity to, but which are distinct from, promises

It was noted earlier that there are a number of English words which commonly act as synonyms for promising and which, in appropriate circumstances, may be taken to signify the act of promising when used by a speaker. There are in addition, however, some terms denoting concepts similar to, but not identical to, the promise, concepts from which promises need to be distinguished. As will be seen, one is in fact a special type of promise, and some of the others also involve acts of commitment.

unilateral juristic acts … such as the making of a will or dereliction of ownership, which can be performed by one person’.

66On the distinction between unilateral and bilateral juridical acts, see Levasseur, Louisiana Law of Obligations, §1.1.2.

Six such concepts sharing similarities with promise are discussed: vows, oaths, threats, gifts, warranties and agreement.

(a)  Vows

Vows and oaths are often treated as if they were interchangeable concepts, largely it seems because some references in classical texts as well as biblical sources have been variously translated either as vows or as oaths. Such conflation is unnecessary, however, because whatever translation of the original source language is adopted, it is possible to draw a conceptual distinction between the vow and the oath: a vow is a promise made to God (or one or more deities in a pantheon),67 whereas an oath is a statement of personal commitment, often made in the presence of others, where God is called as a witness to the sincerity of the statement but where there is not necessarily an identified party intended to benefit from the commitment. As will be seen from the following discussion, vows are generally regarded as laudable acts and, given their nature as promises made to God, commitments requiring strict fulfilment; oaths, by contrast, do not receive such universal approval, especially when made rashly; however, if made, the calling of God as witness also creates strong expectations (if not a strict requirement) that the commitment should be fulfilled, such that, at least in the historical literature, divine punishment was to be expected for breach of the oath (or indeed, in some cases, for having made it at all).

The Old Testament contains five examples of vows (the Hebrew verb is nadar) in which the full nature of the vow is set out within a narrative context.68 These examples also demonstrate a further feature of the Old Testament vow, not one which seems to be conceived as a generally necessary part of a vow: it is expressed in the conditional form, that is, in the form ‘If God will do x, then I/we will do y.’ The conditional nature of each of these Biblical vows may be demonstrated by the first of them (in chronological terms), that of Jacob: Jacob vows that, if God will look after him and provide for him, then he will be faithful to God and set up

67Atiyah, Promises, Morals and Law, provides no definition for a vow but conceives of the concept of a vow so broadly that he can speak of a ‘vow to oneself’ (p. 54), which contradicts the definition of a vow provided here. Atiyah’s musings leave the reader unclear as to what he conceives of as the essence of a vow.

68These being Jacob’s vow of fidelity to God (Gen. 28:20–22), the vow of the people of Israel to attack certain Canaanite cities (Num. 21:12), Jephthah’s vow before his victorious battle (Judges 11:30–31), Hannah’s vow to give her son to God’s service (1 Sam. 1:11), and Absalom’s vow to worship God (2 Sam. 15:8).

a temple to him at Bethel. The condition attached to this vow, as with the other biblical examples, being a counter-performance of God, the vow seems to take on almost the appearance of a contractual offer, though that is perhaps to attempt to analyse the matter too legalistically given the non-legal nature of the texts. In fact, the later Thomistic characterisation of vows suggests, as will be seen below, that they are to be seen as promises (of a religious nature) rather than as contractual offers. The narrative working out of these five biblical vows (they are each fulfilled, in response to God’s positive response to the vow) clearly indicates a biblical approval of vows as commendable sacred acts.69

Aquinas considered vows in the Summa Theologica, defining a vow as ‘a promise made to God’,70 the promisor being the human party and the promisee God. In Aquinas’s view, a vow is by nature a virtuous act.71 Unlike the narrative accounts of biblical vows discussed earlier, much of Aquinas’s treatment of vows relates to unconditional vows, such as the vows taken upon reception of holy orders or by those accepting the religious rule of monastic life, though his analysis is also broad enough to include the conditional vow. As with the understanding explained earlier that a promise requires more than a mere internal act of the will, Aquinas rejects the idea that mere deliberation or intention is sufficient for a vow: a concluded manifestation of the will, sufficient to demonstrate a promise, must be present before a vow is constituted.72

Aquinas posits, as part of the case why vows cannot be dispensed with, that he who makes a vow ‘makes a law for himself, as it were’,73 and thus that vows cannot be broken any more than the law may be. However, in favouring the view that vows may be dispensed with, and that this is not contrary to their origins in ‘natural law and Divine precept’,74 Aquinas argues that such dispensation is consonant with natural law precisely because vows are self-made and may therefore have been undertaken without the maker being able ‘to consider every circumstance’. Here again the natural law is seen to be sufficiently flexible to take account of changed circumstances and not the rigid creation it is characterised to be by utilitarians. Aquinas contrasts the enforceability of vows with the status in

69Indeed, Aquinas explains Jephthah’s vow (see Judges 11) as an example of a good act even though it had an evil consequence (the death of his daughter): Summa Theologica, II-II, Q. 88, Art. 2.

70Summa Theologica, II-II, Q. 88, Art 1.

71Ibid, Art. 2. This conception of the vow emphasises its distinction from a threat (the latter is discussed further below, at p. 45).

72Ibid., Art. 1. 73 Ibid, Art. 10. 74 Ibid., Art. 10.

Roman law of the ordinary promises made between men: whereas the latter may require the fulfilment of certain conditions before they were binding, the former are binding unconditionally upon men and must therefore always be honoured.75

While it is important to have an appreciation of the specialised nature of vows in order to distinguish them from the general idea of promises, given this specialised nature it seems that the influence of biblical and medieval rules concerning vows can only have been of very restricted influence so far as the overall impact of promissory ideas on contract law was concerned. As Chapter 2 will indicate, it was late scholastic thinking about the moral importance of promises in a secular context which was to have the far greater effect upon contractual thinking.

(b)  Oaths

Oath swearing is commonly conceived of, both by writers of the Christian and pre-Christian periods, as a statement by a speaker either of commitment to some future action (for instance, ‘I swear that I shall hunt down my father’s murderer’), or of the truth of a statement presently made or about to be made (‘I swear that I shall tell the truth when giving this evidence’), by which the speaker invokes God (or a god) as a witness to the commitment to act or to the truth of what is said (by adding ‘… so help me God’, or ‘… as God is my witness’, for instance). Aquinas styled these two types promissory oaths (oaths committing to future action) and declaratory oaths (testifying to the truth of a statement).76 In addition, the swearer of the oath may call down some punishment upon himself in the event that he breaks the oath, an addition to the form of the oath especially prevalent in the classical and pre-classical period.77

While the person swearing an oath may commit to the performance of some conduct in favour of another person, this is not a necessary component of all oaths. For that reason, many oaths do not conform to the definition of a promise suggested earlier, in that they lack a commitment to

77The addition of a conditional self-curse to an oath was also a feature of early medieval oaths: see Ibbetson, Historical Introduction, pp. 4–5. See further on classical oaths, Sommerstein and Fletcher, The Oath in Greek Society; Sommerstein et al., The Oath in Archaic and Classical Greece. The idea of vengeance as an element in oaths continued into some early modern literature: thus in Hobbes’s Leviathan, the author states that the swearer of an oath binds himself so that, if he is to break the oath, ‘he renounceth the mercy of his God, or calleth to him for vengeance on himself’ (1,14,31).

do something for another. Often, they are simply commitments to future conduct by the speaker declared before the world in general78 or to a group of people, perhaps members of a local community, by which the speaker wishes to demonstrate the seriousness of his intent through the invocation of a divine witness. The conceptual overlap between promises and some oaths, however, has meant that oaths have often been compared to and analysed alongside promises.

References to oaths abound in classical literature, in both dramatic as well as historical and philosophical texts. In the dramatic context, it has been observed79 that in classical Greek drama the form of the oath (as well as the vow) was often used as a dramatic tool in the recitation of the story of a tragic hero, the oath swearing being conceived of as a foolish act designed to usurp the divinely pre-destined fate of man. Outside the use of oaths as an element in Greek drama, however, classical references to oath swearing are often positive in nature. It is clear from the Greek writers­

that oaths were often made on solemn occasions, such as the making of treaties, alliances, and contracts, in which context the making of oaths was approved of.80 Indeed, the literature suggests a certain pride taken by the Greeks in their making and honouring of oaths, a practice by which they saw themselves as being distinguished from the barbarian peoples, who frequently equivocated.81 Plato mentions oaths favourably in his Republic, conceiving of oath-keeping as a virtuous act. The significance of this for Plato was that the highest aim of moral conduct and thought was human well-being (eudaimonia), and the achievement of such well-being was arrived at through leading a life of excellence (aretē), otherwise called ‘virtue’.82 Oath-keeping, being a virtuous character trait, contributed in Plato’s view to the well-being of the oath keeper.83

78For example, as with the oath of Oedipus that the killer of Laius is not living in his house (Sophocles, Oedipus Tyrannus, 249–51) or the oath of the chorus in Electra that those who do not pay their dues will not go long without suffering (Sophocles, Electra, 1063–65).

79See Schlesinger, Promises, Oaths and Vows, especially Ch. 9 (‘Promising as an element of form and content in Greek drama’).

80See, for instance, the presence of oaths to confirm the decision of the Greeks and Trojans to determine their dispute by single combat (Homer, Iliad, 3.276) and the alliance between Croesus and the Lacedaemonians (Herodotus, Histories, 1.69).

81See for instance the comments on such an attitude recited in Aelian, Historical Miscellany, xiv.2 (Of Agesilaus, and the Barbarians breaking their Oaths).

82This ‘virtuous’ approach to human life and conduct was developed by Aristotle: see further discussion in Ch. 2, pp. 69–72.

83Plato also mentions the judicial use of oaths by various Greek states in his Laws, for instance the practice of exomosia, an oath by a witness that he does not believe a statement put to him to be true (Laws, 936e – 937a) as well as the imagined oath in the ideal

The view of swearing oaths which may be gleaned from classical Greek writers is thus mixed: dramatists used the device of the oath in tales of tragic heroes to suggest that the feature of oath taking which was a prediction about the future of the swearer, in opposition to his fate, was a usurpation of the divine prerogative to determine the future, whereas references to oath swearing in religious or solemn ceremonies, or as simple commitments to tell the truth, rather than as attempts to avoid one’s fate, clearly put oaths in a more positive light. It seems then that for the Greek writers, one needs to distinguish the context of the making of an oath in order to judge whether it is to be seen as a laudable act or not.

In Roman society, oath taking was generally conceived of as a positive act, reflective of fidelity,84 hence Cicero’s remark that the ‘foundation of justice, moreover, is good faith – that is, truth and fidelity to promises and agreements’.85 Oaths were to be ‘sacredly kept’.86 On the other hand, the more mixed attitude to oath swearing seen in Greek society is also visible in the Bible, a source of evident significance and influence in later Christian attitudes to the permissibility and desirability of oaths, as seen from Aquinas’s discussion of biblical texts in his analysis of oaths.87 The overall impression given by passages from the Old Testament of oath swearing is that righteous oaths, though not lightly to be entered into, are not strictly forbidden, and, if made, must be honoured, but that the rash oath, which will often be made for a dishonourable purpose, is a reprobate act and will have undesirable consequences.88 This attitude is consistent with the pattern seen in the classical Greek tests, a similarity which has been argued to indicate a cross-fertilisation of ideology between ancient Greek societies and Hebrew culture.89 There are fewer instances of oath swearing in the New Testament,90 though a dif f icult passage (in the

state of Magnesia of a dikastes that he will judge a matter fairly (Laws, 948e). There was a similar practice of exomosia in the actual courts of Athens: see the example related in Aeschines, Speeches, ‘Against Timarchus’, 67–9.

84The Roman concept of good faith has been intimately linked to the cult of the goddess Fides: see Nifong, ‘Promises Past’.

85‘Fundamentum autem est iustitiae fides, id est dictorum conventorumque constantia et veritas’ (Cicero, De Officiis, 3.7.23).

86‘est enim ius iurandum affirmatio religiosa; quod autem affirmate quasi deo teste promsieris, id tenendum est’ (Cicero, De Officiis, 3.29.104).

87Summa Theologica, II-II, Q. 89.

88Lev. 5:4–5, 6:3,19:12; 1 Kings 2:23–24 (alternatively 3 Kings 2:23–24 in the Vulgate).

89See Schlesinger, Promises, Oaths and Vows, pp. 180–1. Schlesinger cites in support of this view the argument advanced by Albright, From Stone Age to Christianity.

90But see Rom. 1:9; 2 Cor. 1:23; Heb. 6:16.

Gospel of Matthew) stands out which, if taken literally, seems to prohibit any act of swearing.91 The text was, however, subject to later interpretation which resulted in a received view (though not without dissent)92 that oath-making was not strictly prohibited.

This mixed biblical attitude towards oaths is reflected in Aquinas’s view that, while ‘an oath is in itself lawful and commendable’93 it ‘becomes a source of evil to him that makes evil use of it, that is who employs it without necessity and due caution.’94 While oaths and vows are, as previously indicated, sometimes conflated, Aquinas distinguishes the two clearly in the definitions (cited earlier) which he gives to each and also in terms of their theological significance: a vow, being directed towards God, is an act of religion; an oath, by which God’s name is called in confirmation of something, is not such an act of religion. The distinction is an Aristotelian teleological one, made by reference to the respective end of each act.95 While there is thus a Thomist distinction between oaths and promises, a promise might be backed up by an oath. This is an important point, for, where this occurred, medieval canon law gave the ecclesiastical courts jurisdiction for the breach of the promise, as such a breach would also constitute breach of the oath, which was seen as a breach of faith (fidei laesio) and thus a religious matter.96 Significantly in Aquinas’s treatment of promissory oaths, the promissory nature of such oaths mandates that they be kept, for the same reason that, in the Thomist view, promises in general must be kept: the requirement of the virtue of honesty.97 This virtue of honesty, as it is emphasised by both Aristotle and Aquinas, is discussed further in Chapter 2.

Oath swearing was still in Aquinas’s day a common feature of community life, which explains why a comprehensive study on promises must include some discussion of oaths. In the present age, the making of oaths is largely confined to judicial procedures where a confirmation of the truthfulness of evidence to be presented is sought, and to the admittance to office of public officials, officers of important private societies,

91Matt. 5:33–37.

92Various strands of Protestantism have doubted the acceptability of swearing oaths. For instance, the Puritans refused to take certain types of oath, a stance which put them in direct conflict with the Anglican ecclesiastical and juridical authorities of their day. For an historical summary of the competing ideologies underlying this conflict, see Greaves,

Society and Religion in Elizabethan England, pp. 680–92.

93 Summa Theologica, II-II, Q. 89, Art. 2. 94 Ibid. 95 Ibid.

96See further discussion of this point in Chs. 2 and 3.

97Summa Theologica, II-II, Q. 89, Art. 7.