nce at all, but of the _application_ of science.

In the definition which we have attempted to frame of the science of
Political Economy, we have characterized it as essentially an _abstract_
science, and its method as the method _a priori_. Such is undoubtedly
its character as it has been understood and taught by all its most
distinguished teachers. It reasons, and, as we contend, must necessarily
reason, from assumptions, not from facts. It is built upon hypotheses,
strictly analogous to those which, under the name of definitions, are
the foundation of the other abstract sciences. Geometry presupposes an
arbitrary definition of a line, "that which has length but not breadth."
Just in the same manner does Political Economy presuppose an arbitrary
definition of man, as a being who invariably does that by which he may
obtain the greatest amount of necessaries, conveniences, and luxuries,
with the smallest quantity of labour and physical self-denial with which
they can be obtained in the existing state of knowledge. It is true that
this definition of man is not formally prefixed to any work on Political
Economy, as the definition of a line is prefixed to Euclid's Elements;
and in proportion as by being so prefixed it would be less in danger of
being forgotten, we may see ground for regret that this is not done. It
is proper that what is assumed in every particular case, should once for
all be brought before the mind in its full extent, by being somewhere
formally stated as a general maxim. Now, no one who is conversant with
systematic treatises on Political Economy will question, that whenever a
political economist has shown that, by acting in a particular manner, a
labourer may obviously obtain higher wages, a capitalist larger profits,
or a landlord higher rent, he concludes, as a matter of course, that
they will certainly act in that manner. Political Economy, therefore,
reasons from _assumed_ premises--from premises which might be totally
without foundation in fact, and which are not pretended to be
universally in accordance with it. The conclusions of Political Economy,
consequently, like those of geometry, are only true, as the common
phrase is, _in the abstract_; that is, they are only true under certain
suppositions, in which none but general causes--causes common to the
_whole class_ of cases under consideration--are taken into the account.

This ought not to be denied by the political economist. If he deny it,
t