by Immanuel Kant
translated by Thomas Kingsmill Abbott


Ancient Greek philosophy was divided into three sciences: physics,
ethics, and logic. This division is perfectly suitable to the nature
of the thing; and the only improvement that can be made in it is to
add the principle on which it is based, so that we may both satisfy
ourselves of its completeness, and also be able to determine correctly
the necessary subdivisions.
We may call all philosophy empirical, so far as it is based on
grounds of experience: on the other band, that which delivers its
doctrines from a priori principles alone we may call pure
philosophy. When the latter is merely formal it is logic; if it is
restricted to definite objects of the understanding it is metaphysic.
In this way there arises the idea of a twofold metaphysic - a
metaphysic of nature and a metaphysic of morals. Physics will thus
have an empirical and also a rational part. It is the same with
Ethics; but here the empirical part might have the special name of
practical anthropology, the name morality being appropriated to the
rational part.
As my concern here is with moral philosophy, I limit the question
suggested to this: Whether it is not of the utmost necessity to
construct a pure thing which is only empirical and which belongs to
anthropology? for that such a philosophy must be possible is evident
from the common idea of duty and of the moral laws. Everyone must
admit that if a law is to have moral force, i.e., to be the basis of
an obligation, it must carry with it absolute necessity; that, for
example, the precept, "Thou shalt not lie," is not valid for men
alone, as if other rational beings had no need to observe it; and so
with all the other moral laws properly so called; that, therefore, the
basis of obligation must not be sought in the nature of man, or in the
circumstances in the world in which he is placed, but a priori
simply in the conception of pure reason; and although any other
precept which is founded on principles of mere experience may be in
certain respects universal, yet in as far as it rests even in the
least degree on an empirical basis, perhaps only as to a motive,
such a precept, while it may be a practical rule, can never be
called a moral law.
Thus not only are moral laws with their principles essentially
distinguished from every other kind of practical knowledge in which
there is anything empirical, but all moral philosophy rests wholly
on its pure part. When applied to man, it does not borrow the least
thing from the knowledge of man himself (anthropology), but gives laws
a priori to him as a rational being. No doubt these laws require a
judgement sharpened by experience, in order on the one hand to
distinguish in what cases they are applicable, and on the other to
procure for them access to the will of the man and effectual influence
on conduct; since man is acted on by so many inclinations that, though
capable of the idea of a practical pure reason, he is not so easily
able to make it effective in concreto in his life.
A metaphysic of morals is therefore indispensably necessary, not
merely for speculative reasons, in order to investigate the sources of
the practical principles which are to be found a priori in our reason,
but also because morals themselves are liable to all sorts of
corruption, as long as we are without that clue and supreme canon by
which to estimate them correctly. For in order that an action should
be morally good, it is not enough that it conform to the moral law,
but it must also be done for the sake of the law, otherwise that
conformity is only very contingent and uncertain; since a principle
which is not moral, although it may now and then produce actions
conformable to the law, will also often produce actions which
contradict it. Now it is only a pure philosophy that we can look for
the moral law in its purity and genuineness (and, in a practical
matter, this is of the utmost consequence): we must, therefore,
begin with pure philosophy (metaphysic), and without it there cannot
be any moral philosophy at all. That which mingles these pure
principles with the empirical does not deserve the name of
philosophy (for what distinguishes philosophy from common rational
knowledge is that it treats in separate sciences what the latter
only comprehends confusedly); much less does it deserve that of
moral philosophy, since by this confusion it even spoils the purity of
morals themselves, and counteracts its own end.
The present treatise is, however, nothing more than the
investigation and establishment of the supreme principle of
morality, and this alone constitutes a study complete in itself and
one which ought to be kept apart from every other moral investigation.
No doubt my conclusions on this weighty question, which has hitherto
been very unsatisfactorily examined, would receive much light from the
application of the same principle to the whole system, and would be
greatly confirmed by the adequacy which it exhibits throughout; but
I must forego this advantage, which indeed would be after all more
gratifying than useful, since the easy applicability of a principle
and its apparent adequacy give no very certain proof of its soundness,
but rather inspire a certain partiality, which prevents us from
examining and estimating it strictly in itself and without regard to
I have adopted in this work the method which I think most
suitable, proceeding analytically from common knowledge to the
determination of its ultimate principle, and again descending
synthetically from the examination of this principle and its sources
to the common knowledge in which we find it employed. The division
will, therefore, be as follows:

1 FIRST SECTION. Transition from the common rational knowledge of
morality to the philosophical.

2 SECOND SECTION. Transition from popular moral philosophy to the
metaphysic of morals.

3 THIRD SECTION. Final step from the metaphysic of morals to the
critique of the pure practical reason.



Nothing can possibly be conceived in the world, or even out of it,
which can be called good, without qualification, except a good will.
Intelligence, wit, judgement, and the other talents of the mind,
however they may be named, or courage, resolution, perseverance, as
qualities of temperament, are undoubtedly good and desirable in many
respects; but these gifts of nature may also become extremely bad
and mischievous if the will which is to make use of them, and which,
therefore, constitutes what is called character, is not good. It is
the same with the gifts of fortune. Power, riches, honour, even
health, and the general well-being and contentment with one's
condition which is called happiness, inspire pride, and often
presumption, if there is not a good will to correct the influence of
these on the mind, and with this also to rectify the whole principle
of acting and adapt it to its end. The sight of a being who is not
adorned with a single feature of a pure and good will, enjoying
unbroken prosperity, can never give pleasure to an impartial
rational spectator. Thus a good will appears to constitute the
indispensable condition even of being worthy of happiness.
A good will is good not because of what it performs or effects,
not by its aptness for the attainment of some proposed end, but simply
by virtue of the volition; that is, it is good in itself, and
considered by itself is to be esteemed much higher than all that can
be brought about by it in favour of any inclination, nay even of the
sum total of all inclinations. Even if it should happen that, owing to
special disfavour of fortune, or the niggardly provision of a
step-motherly nature, this will should wholly lack power to accomplish
its purpose, if with its greatest efforts it should yet achieve
nothing, and there should remain only the good will (not, to be
sure, a mere wish, but the summoning of all means in our power), then,
like a jewel, it would still shine by its own light, as a thing
which has its whole value in itself. Its usefulness or fruitfulness
can neither add nor take away anything from this value. It would be,
as it were, only the setting to enable us to handle it the more
conveniently in common commerce, or to attract to it the attention
of those who are not yet connoisseurs, but not to recommend it to true
connoisseurs, or to determine its value.
For as reason is not competent to guide the will with certainty in
regard to its objects and the satisfaction of all our wants (which
it to some extent even multiplies), this being an end to which an
implanted instinct would have led with much greater certainty; and
since, nevertheless, reason is imparted to us as a practical
faculty, i.e., as one which is to have influence on the will,
therefore, admitting that nature generally in the distribution of
her capacities has adapted the means to the end, its true
destination must be to produce a will, not merely good as a means to
something else, but good in itself, for which reason was absolutely
We have then to develop the notion of a will which deserves to be
highly esteemed for itself and is good without a view to anything
further, a notion which exists already in the sound natural
understanding, requiring rather to be cleared up than to be taught,
and which in estimating the value of our actions always takes the
first place and constitutes the condition of all the rest. In order to
do this, we will take the notion of duty, which includes that of a
good will, although implying certain subjective restrictions and
hindrances. These, however, far from concealing it, or rendering it
unrecognizable, rather bring it out by contrast and make it shine
forth so much the brighter.
I omit here all actions which are already recognized as inconsistent
with duty, although they may be useful for this or that purpose, for
with these the question whether they are done from duty cannot arise
at all, since they even conflict with it. I also set aside those
actions which really conform to duty, but to which men have no
direct inclination, performing them because they are impelled
thereto by some other inclination. For in this case we can readily
distinguish whether the action which agrees with duty is done from
duty, or from a selfish view. It is much harder to make this
distinction when the action accords with duty and the subject has
besides a direct inclination to it. For example, it is always a matter
of duty that a dealer should not over charge an inexperienced
purchaser; and wherever there is much commerce the prudent tradesman
does not overcharge, but keeps a fixed price for everyone, so that a
child buys of him as well as any other. Men are thus honestly
served; but this is not enough to make us believe that the tradesman
has so acted from duty and from principles of honesty: his own
advantage required it; it is out of the question in this case to
suppose that he might besides have a direct inclination in favour of
the buyers, so that, as it were, from love he should give no advantage
to one over another. Accordingly the action was done neither from duty
nor from direct inclination, but merely with a selfish view.
On the other hand, it is a duty to maintain one's life; and, in
addition, everyone has also a direct inclination to do so. But on this
account the of anxious care which most men take for it has no
intrinsic worth, and their maxim has no moral import. They preserve
their life as duty requires, no doubt, but not because duty
requires. On the other band, if adversity and hopeless sorrow have
completely taken away the relish for life; if the unfortunate one,
strong in mind, indignant at his fate rather than desponding or
dejected, wishes for death, and yet preserves his life without
loving it- not from inclination or fear, but from duty- then his maxim
has a moral worth.
The second proposition is: That an action done from duty derives its
moral worth, not from the purpose which is to be attained by it, but
from the maxim by which it is determined, and therefore does not
depend on the realization of the object of the action, but merely on
the principle of volition by which the action has taken place, without
regard to any object of desire.
*A maxim is the subjective principle of volition. The objective
principle (i.e., that which would also serve subjectively as a
practical principle to all rational beings if reason had full power
over the faculty of desire) is the practical law.



From what has been said, it is clear that all moral conceptions have
their seat and origin completely a priori in the reason, and that,
moreover, in the commonest reason just as truly as in that which is in
the highest degree speculative; that they cannot be obtained by
abstraction from any empirical, and therefore merely contingent,
knowledge; that it is just this purity of their origin that makes them
worthy to serve as our supreme practical principle, and that just in
proportion as we add anything empirical, we detract from their genuine
influence and from the absolute value of actions; that it is not
only of the greatest necessity, in a purely speculative point of view,
but is also of the greatest practical importance, to derive these
notions and laws from pure reason, to present them pure and unmixed,
and even to determine the compass of this practical or pure rational
knowledge, i.e., to determine the whole faculty of pure practical
reason; and, in doing so, we must not make its principles dependent on
the particular nature of human reason, though in speculative
philosophy this may be permitted, or may even at times be necessary;
but since moral laws ought to hold good for every rational creature,
we must derive them from the general concept of a rational being.
When I conceive a hypothetical imperative, in general I do not
know beforehand what it will contain until I am given the condition.
But when I conceive a categorical imperative, I know at once what it
contains. For as the imperative contains besides the law only the
necessity that the maxims* shall conform to this law, while the law
contains no conditions restricting it, there remains nothing but the
general statement that the maxim of the action should conform to a
universal law, and it is this conformity alone that the imperative
properly represents as necessary.

*A maxim is a subjective principle of action, and must be
distinguished from the objective principle, namely, practical law. The
former contains the practical rule set by reason according to the
conditions of the subject (often its ignorance or its inclinations),
so that it is the principle on which the subject acts; but the law
is the objective principle valid for every rational being, and is
the principle on which it ought to act that is an imperative.

There is therefore but one categorical imperative, namely, this: Act
only on that maxim whereby thou canst at the same time will that it
should become a universal law.
Now if all imperatives of duty can be deduced from this one
imperative as from their principle, then, although it should remain
undecided what is called duty is not merely a vain notion, yet at
least we shall be able to show what we understand by it and what
this notion means.
Since the universality of the law according to which effects are
produced constitutes what is properly called nature in the most
general sense (as to form), that is the existence of things so far
as it is determined by general laws, the imperative of duty may be
expressed thus: Act as if the maxim of thy action were to become by
thy will a universal law of nature.
We will now enumerate a few duties, adopting the usual division of
them into duties to ourselves and ourselves and to others, and into
perfect and imperfect duties.*

1. A man reduced to despair by a series of misfortunes feels wearied
of life, but is still so far in possession of his reason that he can
ask himself whether it would not be contrary to his duty to himself to
take his own life. Now he inquires whether the maxim of his action
could become a universal law of nature. His maxim is: "From
self-love I adopt it as a principle to shorten my life when its longer
duration is likely to bring more evil than satisfaction." It is
asked then simply whether this principle founded on self-love can
become a universal law of nature. Now we see at once that a system
of nature of which it should be a law to destroy life by means of
the very feeling whose special nature it is to impel to the
improvement of life would contradict itself and, therefore, could
not exist as a system of nature; hence that maxim cannot possibly
exist as a universal law of nature and, consequently, would be
wholly inconsistent with the supreme principle of all duty.
2. Another finds himself forced by necessity to borrow money. He
knows that he will not be able to repay it, but sees also that nothing
will be lent to him unless he promises stoutly to repay it in a
definite time. He desires to make this promise, but he has still so
much conscience as to ask himself: "Is it not unlawful and
inconsistent with duty to get out of a difficulty in this way?"
Suppose however that he resolves to do so: then the maxim of his
action would be expressed thus: "When I think myself in want of money,
I will borrow money and promise to repay it, although I know that I
never can do so." Now this principle of self-love or of one's own
advantage may perhaps be consistent with my whole future welfare;
but the question now is, "Is it right?" I change then the suggestion
of self-love into a universal law, and state the question thus: "How
would it be if my maxim were a universal law?" Then I see at once that
it could never hold as a universal law of nature, but would
necessarily contradict itself. For supposing it to be a universal
law that everyone when he thinks himself in a difficulty should be
able to promise whatever he pleases, with the purpose of not keeping
his promise, the promise itself would become impossible, as well as
the end that one might have in view in it, since no one would consider
that anything was promised to him, but would ridicule all such
statements as vain pretences.
3. A third finds in himself a talent which with the help of some
culture might make him a useful man in many respects. But he finds
himself in comfortable circumstances and prefers to indulge in
pleasure rather than to take pains in enlarging and improving his
happy natural capacities. He asks, however, whether his maxim of
neglect of his natural gifts, besides agreeing with his inclination to
indulgence, agrees also with what is called duty. He sees then that
a system of nature could indeed subsist with such a universal law
although men (like the South Sea islanders) should let their talents
rest and resolve to devote their lives merely to idleness,
amusement, and propagation of their species- in a word, to
enjoyment; but he cannot possibly will that this should be a universal
law of nature, or be implanted in us as such by a natural instinct.
For, as a rational being, he necessarily wills that his faculties be
developed, since they serve him and have been given him, for all sorts
of possible purposes.
4. A fourth, who is in prosperity, while he sees that others have to
contend with great wretchedness and that he could help them, thinks:
"What concern is it of mine? Let everyone be as happy as Heaven
pleases, or as be can make himself; I will take nothing from him nor
even envy him, only I do not wish to contribute anything to his
welfare or to his assistance in distress!" Now no doubt if such a mode
of thinking were a universal law, the human race might very well
subsist and doubtless even better than in a state in which everyone
talks of sympathy and good-will, or even takes care occasionally to
put it into practice, but, on the other side, also cheats when he can,
betrays the rights of men, or otherwise violates them. But although it
is possible that a universal law of nature might exist in accordance
with that maxim, it is impossible to will that such a principle should
have the universal validity of a law of nature. For a will which
resolved this would contradict itself, inasmuch as many cases might
occur in which one would have need of the love and sympathy of others,
and in which, by such a law of nature, sprung from his own will, he
would deprive himself of all hope of the aid he desires.