Fundamental Principals of the Metaphysic of Morals | Page 2

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 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