Mathematical Exposition of some Doctrines of Political Economy. Second 

 Memoir. By W. Whewell, D.D., Master of Trinity College. 



[Read April 15, 1850.] 



1. There have appeared of late years many works upon the subject of Political Economy 

 in which the reasoning, illustrated by numerical examples or in other ways, is of such a kind 

 that a person of mathematical habits of mind, in reading the works, is naturally led to reflect 

 upon the possibility of putting the reasoning into a general algebraical form, and upon the con- 

 sequences which would result from such a mode of treating the subject. It is evident that such 

 a mathematical mode of investigation would, when the fundamental principles of the subject 

 were once distinctly stated and expressed in algebraical symbols, give the results with a certainty 

 and simplicity of method which would be more satisfactory than special numerical examples, — 

 at least to a mathematician. And among many other advantages of such a process, we may 

 expect that we should obtain these : — that we should see both how the doctrines may be 

 generalized, and how they must be limited, much more easily and clearly than we could do by 

 the light of special numerical examples only. Accordingly, attempts have not been wanting 

 to make such an application of mathematical methods to Political Economy : among which 

 I may refer to a paper of my own, published in the Transactions of this Society*. 



2. It would, however, be to take a very erroneous view of the consequences of this applica- 

 tion of mathematics to Political Economy, to suppose that it can add anything to the certainty 

 of the fundamental principles. There is perhaps in some persons a propensity to believe that 

 any subject, when clothed in a mathematical shape, acquires something of mathematical demon- 

 strative character; and that by applying mathematics to assumed principles of knowledge, we in 

 some measure create a science. I must beg leave very distinctly to repudiate all pretensions 

 of this kind. By stating distinctly our fundamental principles, which such an undertaking as 

 the present requires us to do, we may bring them more clearly under notice and examination 

 than would otherwise be done ; but we add nothing whatever to the evidence of the principles. 

 All that we pretend to say is, that if the conclusions be false, the fallacy must be in the prin- 

 ciples, if the process of deduction be truly mathematical. 



3. The questions which I now intend to consider are some which relate to the connection 

 of demand, supply, and price, whether in the same country, or in different countries. And, first, 

 in the same country. That the price of any commodity depends upon the relation of the 

 demand and the supply is commonly and truly stated. But in order to express this dependance 



" Mathematical Exposition of some Doctrines of Political Economy. 1829. 



