The acquisition of a personal right can never be primary or
arbitrary; for such a mode of acquiring it would not be in
accordance with the principle of the harmony of the freedom of my will
with the freedom of every other, and it would therefore be wrong.
Nor can such a right be acquired by means of any unjust act of another
(facto injusti alterius), as being itself contrary to right; for if
such a wrong as it implies were perpetrated on me, and I could
demand satisfaction from the other, in accordance with right, yet in
such a case I would only be entitled to maintain undiminished what was
mine, and not to acquire anything more than what I formerly had.

  Acquisition by means of the action of another, to which I
determine his will according to laws of right, is therefore always
derived from what that other has as his own. This derivation, as a
juridical act, cannot be effected by a mere negative relinquishment or
renunciation of what is his (per derelictionem aut renunciationem);
because such a negative act would only amount to a cessation of his
right, and not to the acquirement of a right on the part of another.
It is therefore only by positive transference (translatio), or
conveyance, that a personal right can be acquired; and this is only
possible by means of a common will, through which objects come into
the power of one or other, so that as one renounces a particular thing
which he holds under the common right, the same object when accepted
by another, in consequence of a positive act of will, becomes his.
Such transference of the property of one to another is termed its
alienation. The act of the united wills of two persons, by which
what belonged to one passes to the other, constitutes contract.

               19. Acquisition by Contract.

  In every contract there are four juridical acts of will involved;
two of them being preparatory acts, and two of them constitutive acts.
The two preparatory acts, as forms of treating in the transaction, are
offer (oblatio) and approval (approbatio); the two constitutive
acts, as the forms of concluding the transaction, are promise
(promissum) and acceptance (acceptatio). For an offer cannot
constitute a promise before it can be judged that the thing offered
(oblatum) is something that is agreeable to the party to whom it is
offered, and this much is shown by the first two declarations; but
by them alone there is nothing as yet acquired.

  Further, it is neither by the particular will of the promiser nor
that of the acceptor that the property of the former passes over to
the latter. This is effected only by the combined or united wills of
both, and consequently so far only as the will of both is declared
at the same time or simultaneously. Now, such simultaneousness is
impossible by empirical acts of declaration, which can only follow
each other in time and are never actually simultaneous. For if I
have promised, and another person is now merely willing to accept,
during the interval before actual acceptance, however short it may be,
I may retract my offer, because I am thus far still free; and, on
the other side, the acceptor, for the same reason, may likewise hold
himself not to be bound, up till the moment of acceptance, by his
counter-declaration following upon the promise. The external
formalities or solemnities (solemnia) on the conclusion of a contract-
such as shaking hands or breaking a straw (stipula) laid hold of by
two persons- and all the various modes of confirming the
declarations on either side, prove in fact the embarrassment of the
contracting parties as to how and in what way they may represent
declarations, which are always successive, as existing
simultaneously at the same moment; and these forms fail to do this.
They are, by their very nature, acts necessarily following each
other in time, so that when the one act is, the other either is not
yet or is no longer.

  It is only the philosophical transcendental deduction of the
conception of acquisition by contract that can remove all these
difficulties. In a juridical external relation, my taking possession
of the free-will of another, as the cause that determined it to a
certain act, is conceived at first empirically by means of the
declaration and counter-declaration of the free-will of each of us
in time, as the sensible conditions of taking possession; and the
two juridical acts must necessarily be regarded as following one
another in time. But because this relation, viewed as juridical, is
purely rational in itself, the will as a law-giving faculty of
reason represents this possession as intelligible or rational
(possessio noumenon), in accordance with conceptions of freedom and
under abstraction of those empirical conditions. And now, the two acts
of promise and acceptance are not regarded as following one another in
time, but, in the manner of a pactum re initum, as proceeding from a
common will, which is expressed by the term "at the same time," or
"simultaneous," and the object promised (promissum) is represented,
under elimination of empirical conditions, as acquired according to
the law of the pure practical reason.

  That this is the true and only possible deduction of the idea of
acquisition by contract is sufficiently attested by the laborious
yet always futile striving of writers on jurisprudence such as Moses
Mendelssohn in his Jerusalem- to adduce a proof of its rational
possibility. The question is put thus: "Why ought I to keep my
Promise?" For it is assumed as understood by all that I ought to do
so. It is, however, absolutely impossible to give any further proof of
the categorical imperative implied; just as it is impossible for the
geometrician to prove by rational syllogisms that in order to
construct a triangle I must take three lines- so far an analytical
proposition- of which three lines any two together must be greater
than the third- a synthetical proposition, and like the former a
priori. It is a postulate of the pure reason that we ought to abstract
from all the sensible conditions of space and time in reference to the