KEENER ON QUASI-CONTRACTS, 21/ Obligations ' Those imposed by the will of the parties (Contracts) Those imposed = by law To forbear (negative) = Obligations of which breaches are Torts. To act (positive) = Quasi-Contracts. Upon this classification, it will be urged, quasi-contracts are not a mere residuary class formed by exclusion from torts and con- tracts ; but are, on the contrary, a true scientific class founded upon a real generic likeness common to all its members, to wit, that they are imposed by law and are to act. The learned author does not expressly make this classification and, like the other, it is to be gathered, if at all, only by implica- tion. Neither does he say anything to show whether or not, assuming it to be his classification, it is intended to be exhaus- tive. If, however, it is not intended to be exhaustive, that is, if there are obligations not provided for in its scheme, it is obvious that in any given case an obligation could be brought within one of its classes only by showing affirmatively that it possessed the distinguishing marks of that class. To show negatively, for ex- ample, that a specific obligation did not fall either with torts or with contracts, to use, that is, a mere exclusionary method, is not logically sufficient, since it might fall outside of the classification altogether. Unless, therefore, this scheme contains a complete division of obligations, the fallacy of undistributed middle which lurked in all the author's discussion of special cases, such as obligations of record and statutory and other duties, re-appears in a much more fatal form than any which it has hitherto assumed. The author's use of the method of exclusion, however, is an almost conclusive proof that he conceived his divisions to be exhaustive, and therefore this proposed classification does justify his special discussions, not as he wrote them out to be sure, but in their full and complete expression. The first division of obligations creates two classes, those im- posed by the will of the parties and those imposed by operation of law. There is an ambiguity about the phrase, " imposed by law," which the learned author does not attempt to relieve. On the one hand, it may denote the sanction of the law, that is, the aid which the law grants to antecedently existing obligations. In that case, however, it is as applicable to contracts as to any
