Preface. 5 



matical economists have been taunted with the riddle : What is a 

 unit of pleasure or utility ? Edgeworth, following the Physiological 

 Psychologist Fechner, answers : " Just perceivable increments of 

 pleasure are equatable " (p. 99). I have always felt that utility 

 must be capable of a definition which shall connect it with its posi- 

 tive or objective commodity relations. A physicist would certainly 

 err who defined the unit of force as the minimum sensible of mus- 

 cular sensation. Prof. Edgeworth admits his perplexity : " It must 

 be confessed that we are here leaving the terra jirina of physical 

 analogy" (p. 99). Yet he thinks it is "a principle on which we are 

 agreed to act but for which it might be hard to give a reason ;" 

 and again : [such equality] " it is contended, not without hesitation 

 is appropriate to our subject." 



This foisting of Psychology on Economics seems to me «?2appro- 

 priate and vicious. Others besides Prof. Edgeworth have done it. 

 Gossen* and Jevons appeared to regard the " calculus of Pleasure 

 and Pain"f as part of the profundity of their theory. They doubt- 

 less saw no escape from its use. The result has been that " mathe- 

 matics " has been blamed for " restoring the metaphysical entities 

 previously discarded."]; 



These writers with Cournot,§ Menger,|| and Marshall^ appear to 

 me to have contributed the most to the subject in hand. With the 

 exceptions noted I have endeavored not to repeat them but to add a 

 little to them, partly in the theory of the subject and partly in the 

 mode of representing that theory. Readers to whom the subject is 

 new will find the present memoir exceedingly condensed. In the 

 attempt to be brief, the possible uses of the diagrams and mechan- 

 isms have been merely sketched, and elaborate explanations and 

 illustrations have been omitted. I have assumed that my readers are 

 already familiar with (say) Jevons, Walras, Menger or Wieser where 

 illustrations and explanations regarding "final utility" abound. 

 Much of Part II and Appendix I may not be thoroughly intelligible 

 to those not familiar with higher geometrical analysis. These parts 

 are made as brief as possible. 



My especial thanks are due to Prof. Gibbs and Prof. Newton for 

 valuable criticism. 



Irving Fisher. 



Yale University, May, 1892. 



* Menschlich Verhehr., Braunschweig, 1854. f Jevons, p. 23, also pp. 8-9, 



X Dr. Ingram. § Theorie des Richesses, Paris, 1838. 



II Volkswirthschaftslehre, Wien, 1871. U Prin. of. Econ., Macmillan, 1890. 



