ng done valiant service for the will
theory. Not only liability arising from legal transactions but
liability attached to an office or calling, liability attached to
relations and liability to restitution in case of unjust enrichment
have been referred to express or implied undertaking and hence to the
will of the person held. But beneath the surface the so-called
contract by estoppel, the cases of acceptance of a wrongly transmitted
offer, the doctrine that a public utility has no general power of
contract as to facilities or rates except to liquidate the terms of
its relational duties in certain doubtful cases, and cases of
imposition of duties on husband or wife after marriage by change of
law, have caused persistent and recurring difficulties and call
everywhere for a revision of our ideas. Also the objective theory of
contract has undermined the very citadel of the will theory. May we
not refer these phenomena, not to the will of the person bound, but to
another postulate of civilized society and its corollaries? May we not
say that in civilized society men must be able to assume that those
with whom they deal in the general intercourse of society will act in
good faith? If so, four corollaries will serve as the bases of four
types of liability. For it will follow that they must be able to
assume (a) that their fellow men will make good reasonable
expectations created by their promises or other conduct, (b) that they
will carry out their undertakings according to the expectation which
the moral sentiment of the community attaches thereto, (c) that they
will conduct themselves with zeal and fidelity in relations, offices
and callings, and (d) that they will restore in specie or by
equivalent what comes to them by mistake or unanticipated situation
whereby they receive what they could not have expected reasonably to
receive under such circumstances. Thus we come back to the idea of
good faith, the idea of the classical Roman jurists and of the
philosophical jurists of the seventeenth century, out of which the
will theory was but a metaphysical development. Only we give it a
basis in social philosophy where they sought a basis in theories of
the nature of transactions or of the nature of man as a moral
creature.

Looking back over the whole subject, shall we not explain more
phenomena and explain them better by saying that the law enforces the
reasonable expectations arising out of conduct, relations and
situations,