224 HARVARD LAW REVIEW. In any controversy in which the proposition can be referred to as a guide to its decision, one of the parties to it alleges the exist- ence of a state of facts from which he draws the conclusion that the other or one of the others has been unjustly enriched at his expense, and he claims appropriate relief The opposing party denies the allegations or disputes the conclusion to be drawn from them. If the decision of the controversy be in favor of the alleging party, it is clearly no answer to the defeated party to say that he is defeated because he has been unjustly enriched at the other's expense. So to answer would import into the reason the very matter in dispute, which is a clear begging of the question. Simi- larly, if the decision be against the alleging party, it is no answer to him to say that he is defeated because the other has not been unjustly enriched at his expense. The matter in dispute is again drawn into the reason and there is another begging of the question. In either case the proposition is not a reason at all. That is the very vice oi ih^ petitio principii, which, more or less plausibly, pur- ports to give a reason, but fails. It is a mere repetition of a prior assertion and is but one form of an identical proposition. To use the proposition therefore as a reason is only to say, The plaintiff ought to recover, because he ought to recover, or to say, The defendant ought to prevail because he ought to prevail. There is only one other way in which the proposition can, even in appearance, be given as a reason or put to practical use and that is by ascertaining the reason why the acts in question are just or unjust and then ascertaining the obligation of the parties by the standard of justice so obtained. In that event, however, the real reason of deciding is, not the proposition, but this extrinsic stand- ard. This is true, even if the proposition be used as a sort of middle term, in actually rendering the reason. Thus to say to the defeated party, when the decision of the controversy is against him, that he is unjustly enriched at the other's expense because (to take an example) he has obtained money from the other by a false statement of fact, is merely to import an unnecessary term. It is in effect to say, you ought to be defeated because you ought to be defeated because you obtained, money by false pretences. Resorting again to the simile of an equation, it is Hke saying, A = A = B. The middle term in both cases is unnecessary and should be neglected as not actually used. If the argument has so far proceeded correctly, it follows that the doctrine of unjust enrichment, even in its most valid statement, is
