In view of the varying underlying bases of the legal rights which have been enforced in the action of assumpsit, it is not surprising that there is difficulty in reducing to one fixed standard the consideration in all cases. There may still be found several somewhat distinct and conflicting ideas as to what constitutes a sufficient consideration.
1. The idea of promissory estoppel or tort. According to this test, the reason for the enforcement of a promise would be the justifiable reliance upon the promise, making it wrongful for the promisor who has aroused expectation in the promisee and induced him to act, to withdraw from his promise.
2 Occasionally in the early books, consideration is used in a looser sense, as meaning any motive or reason for making a promise; or even as meaning deliberation. Some relics of the first of these meanings may be found in some exceptional cases in modern law, see Pound, 13 111. L. Rev. 435, but it has no acceptance as a general definition.
2. The idea that the consideration is the price requested and received by the promisor for the promise. This idea is undoubtedly the fundamental and as to most cases the generally accepted idea of consideration at the present time. This usage of the word also accords with the usage in executed transactions when we speak of the consideration for a deed or for a sale.4
3. A past indebtedness or other situation which makes it just that a promise should be enforced. This idea is in modem times largely discredited except in certain special classes of cases, which must now be regarded as exceptional.
It is sometimes supposed by critics of the doctrine of consideration that the requirement relates to the form rather than the substance of a contract.5 But this is a misunderstanding. Though a peppercorn may be sufficient consideration for a promise,6 whether or not it is, depends on whether it was in fact the exchange or at least a requested detriment induced by the promise.7 Courts of equity have professed to establish no different criterion of what constitutes a contract from that fixed by courts of law. On certain matters, however, equitable doctrines have arisen which are logically inconsistent with any principle of consideration recognized by courts of law. The most striking of the cases where obligations have been enforced in equity without consideration valid at law are:
Since a trust involves both a personal obligation and a property right, the doctrine established by Lord Eldon that a voluntary declaration of trust without change of possession creates an enforceable right,9 is inconsistent with the principles that a promise is not binding without consideration, and that a gift without delivery is ineffectual.10
4See Lsngdell, Summary of Con-tnets, Sec.Sec. 45 et seq.
5See, e. g, Markby, Elements (6th ed), 309; Loraueo, 28 Yale L. J. 621.
6Infra, Sec. 115.
8 See a full discussion of Consideration in Equity by Pound in 13 111. L. Rev. 435.
9 Ex parte Pye, 18 Ves. 140; Jones v. Look, L. R. 1 Ch. 25; Ames's Cas. Trust (2d ed.), 125 n.