itions. To describe, again, the play of a number of reciprocal
forces, we have to find what mathematicians call an 'independent
variable': some one element in the changes on which all other changes
will depend. That element, roughly speaking, ultimately comes out to
be 'labour.' The simplicity of the system gave an impression both of
clearness and certainty, which was transferred from the reasoning to
the premises. The facts seemed to be established, because they were
necessary to the system. The first step to an estimate of the value of
the doctrine would be to draw up a statement of the 'postulates'
implied. Among them, we should have such formulae as the single rate of
profits and wages; which imply the 'transferability' of labour and
capital, or the flow of either element to the best-paid employment. We
should have again the Malthusian doctrine of the multiplication of
labour up to a certain standard; and the fact that scarcity means
dearness and plenty cheapness. These doctrines at least are taken for
granted; and it may perhaps be said that they are approximations which
only require qualifications, though sometimes very important
qualifications, to hold good of the society actually contemplated.

They were true enough to give the really conclusive answer to many
popular fallacies. The type of sophistry which Ricardo specially
assailed was that which results from neglecting the necessary
implications of certain changes. The arguments for the old 'mercantile
theory'--for 'protection' of industry, for the poor-law, for resisting
the introduction of machinery, the fear of 'gluts' and all manner of
doctrines about the currency--were really exposed by the economists
upon the right grounds. It was absurd to suppose that by simply
expanding the currency, or by making industry less efficient, or
forcing it to the least profitable employments, you were increasing
the national wealth; or to overlook the demoralising effects of a
right to support because you resolved only to see the immediate
benefits of charity to individuals. It is true, no doubt, that in some
cases there might be other arguments, and that the economists were apt
to take a narrow view of the facts. Yet they decisively exploded many
bad arguments, and by the right method of enforcing the necessity of
tracing out the whole series of results. It was partly to their
success in confuting absurd doctrines that their confidence was due;
though the confidence was e