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,
which has to do with determinate objects and the laws to which they
are subject, is again two-fold; 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.
[Footnote: The word "law" is here used in two different senses, on
which see Whately's Logic, Appendix, Art. "Law."] 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 hand, 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 two-fold 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.
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 so 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 only--if 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
whnat 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 moral philosophy, perfectly cleared of everything
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. Every one 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
circumstanced in the world in which he is placed, but a priori
simply in the conceptions 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 judgment 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 concrete 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 in 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
[Footnote: Johann Christian Von Wolf (1679-1728) was the author of
treatises on philosophy, mathematics, &c., which were for a long
time the standard text-books in the German Universities. His
philosophy was founded on that of Leibnitz.] 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 kind-say 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 practical 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 asked for in a philosophy which passes no judgment 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 a
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.