“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 it 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 account.” I have extracted this long passage because it is a clear statement of an original view of the science of Political Economy,--a view so plausible, indeed so philosophical, that I feel bound either to adopt it, or to state fully my reasons for rejecting it. I am not aware of any writer, except, perhaps, Mr. Merivale, who has expressed a formal concurrence in Mr. Mill’s doctrine; but Mr. Ricardo has practically assented to it. His treatment of the science, indeed, is still more abstract than that proposed by Mr. Mill. He adds to Mr. Mill’s hypothesis other assumptions equally arbitrary; and he draws all his illustrations, not from real life, but from hypothetical cases. Out of these materials he has framed a theory, as to the distribution of wealth, possessing almost mathematical precision.