alternative be called a mutual contract, onerous and mutual thus being held to be synonymous. However, some jurisdictions choose to distinguish onerous contracts from mutual contracts, on the basis that a mutual contract, while certainly onerous, must have the additional feature that at least some of the duties of each party under the contract are reciprocal, or synallagmatic. This distinction is made because it is conceivable that a contract might be onerous, imposing duties on both parties, but the duties of each may not find a counterpart in the duties of the other. An example of an onerous but non-mutual contract is mandate, where the duty of the mandatory to concern himself with the task allotted to him is not the synallagma of the mandant’s duty to pay any expenses of the mandatory, each duty being independent of the other. By contrast, a mutual contract is one where there are at least some reciprocal undertakings, even if others are independent. In jurisdictions with a doctrine of mutual consideration, all contracts51 should in theory be seen as being mutual to at least some extent, as the consideration paid by each party is viewed as having been given in exchange for the other’s undertaking.

The distinction between mutual and onerous contracts is recognised in South African52 and Louisiana53 law, and in theory in Scots law too, though it is hard to find any theoretical discussion of the distinction in the latter. This distinction between onerous/non-gratuitous contracts and mutual/reciprocal contracts is a useful one, the latter being a subset of the former.

(b)  Conditionality54

Obligations like promise may be conditional or unconditional (otherwise ‘absolute’), the two being opposites.55 This is a crucial flexibility of

51Save those undertaken by way of deed or under seal.

52See Van der Merwe et al., Contract, p. 10, who state that in South African law the mutual or synallagmatic contract is a ‘particular type of multilateral contract. It differs from other multilateral contracts in that – according to the intention of the parties – the one party is bound to perform in exchange for performance by the other party.’

53The Louisiana Civil Code defines synallagmatic contracts at Art. 1908, and onerous ­contracts at Art. 1909.

54The discussion here seeks to be as inter-jurisdictional as possible. To that end, jurisdiction specific meanings of the term ‘condition’ or ideas of conditionality are avoided. Thus, there is no discussion of certain peculiarly Common law meanings of the word condition, such as a contract term in general, or a contract term performance of which goes to the root of the contract and which therefore gives a right to terminate the contract if the term is not fulfilled.

55See DCFR, Art. III.-1:106.

promise, as it enables the idea of promise to be employed to describe the nature of contract as an accepted conditional promise (or an exchange of promises, if mutual consideration is held to be a requirement for a contract). But what does conditionality mean? It is important to distinguish a number of meanings.

In a promissory setting, the idea of conditionality can be used to denote whether or not a binding obligation has been assumed by the speaker of the potentially promissory words. With that possible meaning in mind, the following four types of statement can be tested for their conditionality:

(1) Type 1 examples:

‘I promise to pay you £100 next Monday.’ ‘I promise to marry you.’

(2) Type 2 examples:

‘I promise to pay you £100 if you pass your driving test.’

‘I promise to employ you if your current employer dismisses you.’

‘I promise to buy you dinner if my football team wins its game today.’

‘I promise to pay to have you flown home for medical treatment if you contract malaria.’

(3) Type 3 examples:

‘I promise to buy the painting if my wife likes it.’

‘I promise to pay you £100 if you give me your clock.’

‘I promise to go to the cinema with you tonight if you pay for the tickets.’

(4) Type 4 example:

‘I promise to pay you £100 every Sunday unless and until you cease going to Church.’

Note, that in each of these types of case, the condition must not be certain to happen, or else the promisor will be bound to fulfil the promise on the occurrence of the certain event, and the promise cannot be said to be conditional.56 For instance, if the promise is ‘I promise to pay you £100 the next time it rains’, although the time for performance of the promise is as yet uncertain, we know that it is going to rain (precipitation being a universally recurring phenomenon), and thus the performance of the promisor is not conditional even if the time for performance remains uncertain until it rains. By contrast, a promise to buy an umbrella on condition that it rain tomorrow is a valid conditional promise, as whether it will rain tomorrow is an uncertain future event.

56As the first sentence of Art. 1767 of the Louisiana Civil Code states: ‘A conditional obligation is one dependent upon an uncertain event.’ The same requirement of uncertainty is stated in respect of conditional obligations in the DCFR, Art. III.-1:106.

In the first type of case, there is nothing in what is said to suggest that the promisor is not immediately bound by an obligation (whether it be of a moral or legal kind), so the promise is unconditional.

In the second type of case, however, the promise is, in some sense, conditional,­ but in what sense? Here, it could be argued, the person making­ the statement intends to be bound to the promise immediately it is uttered, but that performance is not intended unless and until the stipulated­ event (for instance, the promisee’s passing his driving test) occurs. This is, of course, a matter of interpretation, and it might be argued that a different state of affairs was intended by the promisor (namely, that no binding obligation was intended until the contingency was met), but it is certainly one reasonable interpretation of the examples given under type 2 that the statements give rise to an immediately binding obligation,­ albeit one where performance is contingent upon the­ occurrence of the stipulated future event. The importance of that analysis­ would be that, once the statement had been made, the speaker would not be free to withdraw from the obligation. However, in those examples of this type where the contingency relates to some stipulated conduct of the hearer, the hearer is under no obligation to perform the conduct indicated (for instance to pass his driving test), though he is at liberty to attempt so to perform; if he does so perform, then he has fulfilled the condition of the promise and may seek the promised benefit from the promisor. Thus, with this sense of conditionality, the promise is conditional because, though immediately binding on the promisor once uttered, its performance is contingent on the occurrence of an uncertain future event. So, the idea of conditionality can relate to the performance of the promise, without there being any doubt that there is an immediately binding obligation.

In the third type of case, one interpretation of what is objectively intended by the promisor is that the nature of the statement as a binding obligation is itself conditional, the condition being that the person to whom the statement is made is himself willing to undertake an obligation of the type indicated (for instance, the obligation to transfer ownership in some goods). Here, therefore, the conditionality relates primarily to the nature of the statement as an obligation. It is not intended to be treated as an immediately binding obligation, but is, pro tem, merely a proposed obligation, and is to retain such nature until the condition is fulfilled. This type of conditionality, where the condition denotes that the obligation is not binding unless and until a future contingent event occurs, is in many jurisdictions styled a condition ‘suspensive’ of the

obligation.57 In this third type of case, the statement is also conditional in the sense applicable in the second type of case, namely that there is uncertain conduct of the other party upon which performance rests, but the primary sense of conditionality is as to the nature of the statement as an obligation at all. Neither offer nor acceptance has obligational force unless it is met with a reciprocal conditional commitment from the other party. It is the sense applicable to this type of case which allows contractual offers and acceptances to be characterised as conditional promises, and thus for the contract as a whole to be characterised in a promissory fashion.

In the fourth type of case, the type of conditionality concerned is likely (as with the third example) to be objectively interpreted as relating to the nature of the statement as an obligation. In this case, however, the promise gives rise immediately to a binding obligation, but such obligation may cease to be binding if and when a contingent future event occurs (in the example given, that the promisee ceases to go to Church). In many jurisdictions, this sort of conditional obligation is referred to as ‘resolutive’ (or ‘resolutory’).58

Are any types of condition impermissible? Some conditions may stipulate­ unlawful or immoral conduct, and so for those reasons may invalidate a promise. In addition, however, a condition which undermines­

the very idea that a binding commitment was being undertaken in the first place would seem to be impermissible in the sense that it would prevent fulfilment of the requirement that a speaker must commit to a future act. Thus, if the condition stipulated related to whether or not the person making the commitment still wished to perform the commitment at a future date, this would bring in to question whether any commitment was seriously being undertaken to begin with. So, for instance, the statement ‘I promise to pay you £100 next Monday, if I have not changed my mind by

57The situation is in fact even more complex than suggested. In some jurisdictions, a ­so-called suspensive condition may either prevent an obligation from coming into being until the condition is fulfilled, or there may be an obligation in force immediately, from which neither party is permitted to withdraw, but the parties rights and duties under the obligation will not be enforceable unless and until the suspensive condition is purified. Which type of effect is intended by the relevant party or parties is a matter for the court to interpret. See, for instance, for Scots Law, the discussion at McBryde, Contract, paras. 5–35 to 5–40. In the DCFR, a suspensive obligation is one which, until fulfilment of the condition, does not have obligatory effect: see Art. III.-1:106(2).

58As the third sentence of Art. 1767 of the Louisiana Civil Code states: ‘If the obligation may be immediately enforced but will come to an end when the uncertain event occurs, the condition is resolutory.’ The DCFR also makes provision for resolutive conditions: see Art. III.-1:106(1),(3).

then’ would not seem capable of being considered a promise because the condition attached undermines the very notion that any definite commitment has been undertaken to begin with.59 On the other hand, a condition which permits the promisor to revoke the promise at some future point, but is not so sweeping as to be suggestive of a lack of an original intention to be bound at all, might be argued to be a permissible condition. Thus, a promise of the type ‘I promise to pay you £1,000 on 1st January, but I retain the power to revoke this promise should I deem the changed nature of our relationship so to warrant’ might fall within the category of valid promises, albeit that a fairly wide power of revocation is retained by the promisor.60

Are any other senses of conditionality relevant to the debate about the nature of promises? What of the argument referred to earlier of some linguistic philosophers that it is essential to the idea of a promise that the words spoken produce in the hearer an understanding of the binding nature of what is being said: without such a ‘condition’ being fulfilled, there can be no promise. That might seem to give rise to a further sense of conditionality, one which holds that all promises are conditional because they depend upon a subjective understanding in the hearer being attained before the statement can be considered a promise. However, as the argument that the words spoken by a promisor require to induce such an understanding on the hearer’s part before a statement can count as a promise has been argued earlier to be controversial and probably misguided, it is proposed to discount this meaning of conditionality.

A further possible sense of conditionality has been said to lie in the fact that all promises are conditional because they relate to future acts, and all future acts are inherently uncertain because we cannot know whether circumstances prevailing in the future will permit performance of the

59Such reasoning would appear to underlie the first sentence of Art. 1770 of the Louisiana Civil Code: ‘A suspensive condition that depends solely on the whim of the obligor makes the obligation null.’ This point has long been acknowledged by jurists. For instance, Pufendorf states in his Elementorum that ‘[i]t must be observed, furthermore, that promises are unavailing and null, when the condition under which the promise is made has been put under my own pleasure, for example … “You will have ten pieces of gold from me, when it pleases me”’ (I.xii.11).

60Atiyah suggests that a promise of future performance is by nature irrevocable (Promises, Morals and Law, pp. 178–9) unless the promise is made for no consideration or is not relied upon (p. 181). This suggestion is made in the context of an argument that a promise is a type of consent to an obligation, and while present consents can normally be later withdrawn, a promisor is committing himself to a future performance which usually indicates that his consent will not be revocable.