Promises as obligations: morality and law

obligation (obligatio) was literally a physical bond in the early days of Roman law. By the classical period of Roman law, the concept of an obligation had developed beyond a literal power to bind a wrongdoer and had come to incorporate the class of interpersonal legal relationships – bonds or ties only in the figurative sense – deriving both from harmful conduct (said to arise ex delicto) as well as those arising voluntarily (ex contractu). At least by classical times, this idea of a figurative obligation encompassed the whole of the relationship binding the relevant parties, and thus both the duty imposed on the one and the corresponding right given to the other.2 In Western legal systems which derive from Roman law, an obligation thus entails a corresponding right and duty deriving from a legal bond or tie between the obliged (debtor) and the obligee (creditor). Such a bond naturally implies a power in the obligee to compel the obliged to perform the relevant duty. Bearing in mind the element of performance of a duty, it will be obvious why promise falls within the class of obligations. The power given to promisees at law to enforce performance are considered at various later points in this work.

2.  Taxonomies of obligations in morality and law

Recognising that promise is a type of obligation leads to the question of where promise fits in taxonomically with other obligations recognised by moral and legal systems. The law and morality tend to give somewhat different answers to that question, even though each sees the place of promise within its own system as determined by the nature of the binding force it ascribes to promise. In morality, there are a number of possible classifications of interpersonal duties.3 For instance, one basis of a classification would be to use the class of person to whom the moral duty is undertaken: to God (as with those promises which are constituted as vows),

2While commonly, in modern layman’s usage, the term obligation denotes only the duty side of such a bond, in this work the classical sense will be maintained unless the context indicates otherwise.

3What is offered in the main text is not a comprehensive analysis of moral systems or a comprehensive classification of the moral rules or principles operating in such a system, about which much has been written (see, for instance, Sheng, ‘On the Nature of Moral Principles’), but rather a discussion of some possible moral classifications of obligations, a much more narrowly focused question. Promise as a type of obligation can, of course, be said to derive from a moral principle (whether it be a broad moral principle such as virtue or utility, or a more focused principle such as that one should keep one’s word), but the source of the obligatory force of a promise as perhaps lying in such a moral principle is the subject of later discussion in this chapter.

family, friends, community, strangers, or even perhaps to self (though the concept of a duty, including a promise, owed to oneself is not one which fits with the definition of a promise suggested in Chapter 1). The rationale behind such a classification would be to stress varying degrees of importance to be attached to the nature of the obligation, with promises made to God or family being considered stronger bonds than those made to strangers. Such an approach is quite different to that taken by the law, which sees all properly constituted obligations as having the same legal force.4 An alternative way of classifying moral obligations would be by reference to the nature of the duty undertaken: thus a promise made by A to B to go on holiday might be seen as less morally binding than one made by A to a dying B to provide for B’s child. Again, because all legally recognised duties have a unitary obligatory effect, none being more or less of a powerful bond at law than others, the law would not recognise that sort of division either. The point about morality’s distinction between duties owed to one type of person and another, or between those concerning one type of conduct and another, is that such classifications can be thought useful to human beings in helping them to decide how to prioritise undertakings, and thus to rank them in case of conflict, so that, for instance, a duty to one’s spouse would, in case of conflict, trump that of one owed to a stranger. Moral rankings of duties also act as badges of the varying degrees of importance attached by people to certain relationships and to certain types of conduct, and thus operate socially as signs of the social hierarchy and of the hierarchy of types of laudable conduct. How are such moral classifications arrived at? That is a complex sociological question, but it seems to depend in large part upon how promises are seen to derive their moral force. This is a far from uncontroversial question, and much of the substance of this chapter will be taken up with considering it.

Given the traditional linkage of morality and law by human societies, an inevitably related question to the moral classification of promises is how the class of obligations is arranged by the law, that discipline from which the term obligation sprang. Because much of the detail of this question is discussed in Chapter 3, only a summary is offered at this point. Obligations as a legal taxonomic category describe the class of private law duties arising between persons. As interpersonal duties they give rise to so-called rights in personam. Such are to be distinguished from property law duties, which arise in relation to things and not persons,

4Human law is, of course, not concerned with promises made to God, the law being ­concerned with relationships between human beings.

and so give rise to so-called rights in rem. Within the class of obligations, ­further subdivisions are possible. The classical Roman division was a twofold one between those obligations arising by wrongdoing (ex delicto) and those arising by agreement (ex contractu), a division later expanded to a fourfold one of (1) those arising by wrongdoing, (2) those arising as if by wrongdoing (quasi ex delicto), (3) those arising by agreement, and (4) those arising as if by agreement (quasi ex contractu).5 The Roman classification is no longer adhered to by modern legal systems, which typically prefer to conceive of obligations as arising either voluntarily or involuntarily (though this distinction has some connection with the Roman categories of ex contractu and ex delicto), that is to say by virtue of a voluntary acceptance of the duty or without reference to such voluntary acceptance. Thereafter voluntary and involuntary types can be further subdivided. Within the voluntary class there is, of course, primarily contract. Many systems would not go further than recognising this single member of that class. However, if unilateral promises are given effect by a legal system, then it is possible (though not necessary) to conceive of such unilateral promises as a separate category of obligation within the class of voluntary obligations.6 Within the involuntary class are placed delict/tort, unjustified enrichment and (where recognised in a legal system) negotiorum gestio.

Thus, just as moral classifications of obligations can be said to depend upon the alleged source of the moral nature of the duty (an issue explored later in this chapter), so too the typical modern legal classification of obligations hinges crucially upon the alleged source of the obligation’s force, whether as arising voluntarily or involuntarily, that is whether deriving from the free acceptance of the obliged to be bound to the duty or without reference to such free acceptance but rather by force of law. It was fashionable in the 1970s and 1980s to attack such a division,7 but such attacks have ultimately proved unconvincing, having failed both to take account of the importance attached by the law to personal freedom as well as to propose a better working classification for the law.8

5See further discussion in Ch. 3.

6There is also the question of where to place third party rights arising under contract, either as part of contract, or as a sui generis species of voluntarily assumed obligation. This ­question is discussed in Ch. 5 of this work.

7See, for instance, Atiyah, Essays on Contract, and Gilmore, The Death of Contract.

8Apart from the standard modern classification of obligations into voluntary and involuntary species, there are other criteria which can be used to describe obligations. Some of these were discussed in Ch. 1. Hence, obligations may be described as unilateral or ­bilateral (or multilateral), gratuitous or onerous, and as revocable or irrevocable.