PREFACE

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.

All rational knowledge is either material or formal: the former

considers some object, the latter is concerned only with the form of

the understanding and of the reason itself, and with the universal

laws of thought in general without distinction of its objects.

Formal philosophy is called logic. Material philosophy, however, has

to do with determinate objects and the laws to which they are subject,

is again twofold; for these laws are either laws of nature or of

freedom. The science of the former is physics, that of the latter,

ethics; they are also called natural philosophy and moral philosophy

respectively.

Logic cannot have any empirical part; that is, a part in which the

universal and necessary laws of thought should rest on grounds taken

from experience; otherwise it would not be logic, i.e., a canon for

the understanding or the reason, valid for all thought, and capable of

demonstration. Natural and moral philosophy, on the contrary, can each

have their empirical part, since the former has to determine the

laws of nature as an object of experience; the latter the laws of

the human will, so far as it is affected by nature: the former,

however, being laws according to which everything does happen; the

latter, laws according to which everything ought to happen. Ethics,

however, must also consider the conditions under which what ought to

happen frequently does not.

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 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.

All trades, arts, and handiworks have gained by division of

labour, namely, when, instead of one man doing everything, each

confines himself to a certain kind of work distinct from others in the

treatment it requires, so as to be able to perform it with greater

facility and in the greatest perfection. Where the different kinds

of work are not distinguished and divided, where everyone is a

jack-of-all-trades, there manufactures remain still in the greatest

barbarism. It might deserve to be considered whether pure philosophy

in all its parts does not require a man specially devoted to it, and

whether it would not be better for the whole business of science if

those who, to please the tastes of the public, are wont to blend the

rational and empirical elements together, mixed in all sorts of

proportions unknown to themselves, and who call themselves independent

thinkers, giving the name of minute philosophers to those who apply

themselves to the rational part these, I say, were warned not

to carry on two employments together which differ widely in the

treatment they demand, for each of which perhaps a special talent is

required, and the combination of which in one person only produces

bunglers. But I only ask here whether the nature of science does not

require that we should always carefully separate the empirical from

the rational part, and prefix to Physics proper (or empirical physics)

a metaphysic of nature, and to practical anthropology a metaphysic

of morals, which must be carefully cleared of everything empirical, so

that we may know how much can be accomplished by pure reason in both

cases, and from what sources it draws this its a priori teaching,

and that whether the latter inquiry is conducted by all moralists

(whose name is legion), or only by some who feel a calling thereto.

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.

Let it not be thought, however, that what is here demanded is

already extant in the propaedeutic prefixed by the celebrated Wolf

to his moral philosophy, namely, his so-called general practical

philosophy, and that, therefore, we have not to strike into an

entirely new field. just because it was to be a general practical

philosophy, it has not taken into consideration a will of any

particular one which should be determined solely from a

priori principles without any empirical motives, and which we might

call a pure will, but volition in general, with all the actions and

conditions which belong to it in this general signification. By this

it is distinguished from a metaphysic of morals, just as general

logic, which treats of the acts and canons of thought in general, is

distinguished from transcendental philosophy, which treats of the

particular acts and canons of pure thought, i.e., that whose

cognitions are altogether a priori. For the metaphysic of morals has

to examine the idea and the principles of a possible pure will, and

not the acts and conditions of human volition generally, which for the

most part are drawn from psychology. It is true that moral laws and

duty are spoken of in the general moral philosophy (contrary indeed to

all fitness). But this is no objection, for in this respect also the

authors of that science remain true to their idea of it; they do not

distinguish the motives which are prescribed as such by reason alone

altogether a priori, and which are properly moral, from the

empirical motives which the understanding raises to general

conceptions merely by comparison of experiences; but, without noticing

the difference of their sources, and looking on them all as

homogeneous, they consider only their greater or less amount. It is in

this way they frame their notion of obligation, which, though anything

but moral, is all that can be attained in a philosophy which passes no

judgement at all on the origin of all possible practical concepts,

whether they are a priori, or only a posteriori.

Intending to publish hereafter a metaphysic of morals, I issue in

the first instance these fundamental principles. Indeed there is

properly no other foundation for it than the critical examination of a

pure practical Reason; just as that of metaphysics is the critical

examination of the pure speculative reason, already published. But

in the first place the former is not so absolutely necessary as the

latter, because in moral concerns human reason can easily be brought

to a high degree of correctness and completeness, even in the

commonest understanding, while on the contrary in its theoretic but

pure use it is wholly dialectical; and in the second place if the

critique of a pure practical reason is to be complete, it must be

possible at the same time to show its identity with the speculative

reason in a common principle, for it can ultimately be only one and

the same reason which has to be distinguished merely in its

application. I could not, however, bring it to such completeness here,

without introducing considerations of a wholly different kind, which

would be perplexing to the reader. On this account I have adopted

the title of Fundamental Principles of the Metaphysic of Morals

instead of that of a Critical Examination of the pure practical

reason.

But in the third place, since a metaphysic of morals, in spite of

the discouraging title, is yet capable of being presented in popular

form, and one adapted to the common understanding, I find it useful to

separate from it this preliminary treatise on its fundamental

principles, in order that I may not hereafter have need to introduce

these necessarily subtle discussions into a book of a more simple

character.

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

consequences.

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.