deviate from the principle of duty is beyond all doubt wicked; but
to be unfaithful to my maxim of prudence may often be very
advantageous to me, although to abide by it is certainly safer. The
shortest way, however, and an unerring one, to discover the answer
to this question whether a lying promise is consistent with duty, is
to ask myself, "Should I be content that my maxim (to extricate myself
from difficulty by a false promise) should hold good as a universal
law, for myself as well as for others?" and should I be able to say
to myself, "Every one may make a deceitful promise when he finds
himself in a difficulty from which he cannot otherwise extricate
himself?" Then I presently become aware that while I can will the lie,
I can by no means will that lying should be a universal law. For
with such a law there would be no promises at all, since it would be
in vain to allege my intention in regard to my future actions to those
who would not believe this allegation, or if they over hastily did
so would pay me back in my own coin. Hence my maxim, as soon as it
should be made a universal law, would necessarily destroy itself.

I do not, therefore, need any far-reaching penetration to discern
what I have to do in order that my will may be morally good.
Inexperienced in the course of the world, incapable of being
prepared for all its contingencies, I only ask myself: Canst thou also
will that thy maxim should be a universal law? If not, then it must be
rejected, and that not because of a disadvantage accruing from it to
myself or even to others, but because it cannot enter as a principle
into a possible universal legislation, and reason extorts from me
immediate respect for such legislation. I do not indeed as yet discern
on what this respect is based (this the philosopher may inquire),
but at least I understand this, that it is an estimation of the
worth which far outweighs all worth of what is recommended by