156 Professor Whewell on the 



difficulties and perplexities which may occur in consequence of 

 any complexity in the line of deduction, and are secure from any 

 risk of vitiating the course of our reasoning by tacit assumptions 

 or unsteady applications of our original principles. Perhaps it 

 might not be difficult to shew that in several speculations on these 

 subjects, such errors have not been altogether avoided. And there 

 is probably a considerable class of readers who will find the doc- 

 trines of Political Economy, when put in a mathematical shape, 

 more clear, compendious, and manageable than in the works to 

 which I refer. I may add also, that the mathematical formula- 

 which I shall obtain, will be, at the same time, both much more 

 exact and much more general than the numerical examples in 

 which writers on the subject are in the habit of embodying and 

 illustrating their reasonings. 



2. I have said that the doctrines of Political Economy have 

 been supposed to be reduced to a few simple fundamental prin- 

 ciples ; and my business will be to state these principles and 

 to trace their consequences. The mathematical investigation pro- 

 ceeds from these principles as postulates, and has no concern 

 with their truth or falsehood. To extricate such principles from 

 the mass of facts which observation of the world and of ourselves 

 teaches us, — to establish the reality, number, and limits of such 

 laws, — these are offices which belong to a branch of philosophy 

 altogether different from that with which the mathematician, in 

 the proper sense of the name, has to deal. Such a task is far 

 from being either short or easy; and it would be very hasty to 

 take for granted that it is already completed, or even that any 

 considerable portion of it is performed. For my own part, I do 

 not conceive that we are at all justified in asserting the princi- 

 ples which form the basis of Mr. Ricardo's system, either to be 



