Bindingness of Consent
Voluntary Commitment (Hart)
The voluntary commitment of promises and contracts makes them morally binding.
H. L. A Hart (Legal Philosopher). “Are There Any Natural Rights.” http://isites.harvard.edu/fs/docs/icb.topic97122.files/Hart.pdf
The most obvious cases of special rights are those that arise from promises. By promising to do or not to do something, we voluntarily incur obligations and create or confer rights on those to whom we promise; we alter the existing moral independence of the parties' freedom of choice in relation to some action and create a new moral relationship between them, so that it becomes morally legitimate for the person to whom the promise is given to determine how the promisor shall act. The promisee has a temporary authority or sovereignty in relation to some specific matter over the other's will which we express by saying that the promisor is under an obligation to the promisee to do what he has promised. To some philosophers the notion that moral phenomena-rights and duties or obligations-can be brought into existence by the voluntary action of individuals has appeared utterly mysterious; but this I think has been so because they have not clearly seen how special the moral notions of a right and an obligation are, nor how peculiarly they are connected with the distribution of freedom of choice; it would indeed be mysterious if we could make actions morally good or bad by voluntary choice. The simplest case of promising illustrates two points characteristic of all special rights: (1) the right and obligation arise not because the promised action has itself any particular moral quality, but just because of the voluntary transaction between the parties; (2) the identity of the parties concerned is vital - only this person (the promisee) has the moral justification for determining how the promisor shall act. It is his right; only in relation to him is the promisor's freedom of choice diminished, so that if he chooses to release the promisor no one else can complain.