F.— ECONOMIC SCIENCE AND STATISTICS 143 



spectus of the field as a whole, on which the validity of the prescriptions 

 depends, on the other. 



I regard this division of analysis into two departments as of importance, 

 (i) because it reconciles the fairly copious array of economic precept with 

 the very limited power of prediction, and (ii) because only by it can the 

 empirical grounds of our general propositions be properly sorted out. I 

 should add that recent methodological speculation appears to attach too 

 much importance to the part played by the general theory of value and 

 too little to that of the equi-marginal maxim in the history of economic 

 thought. 



Recently economists have had the very proper ambition of obtaining 

 greater knowledge of causal sequences than is vouchsafed by deductions 

 from the Law of Demand. The phenomena of the Trade Cycle have been 

 a special stimulus in this direction. But once they leave the plane of high 

 generality which pertains to those deductions, their generalisations are 

 likely to have a much lower degree of probability. All the difficulties 

 associated with the complex and unamenable nature of the phenomena, 

 which they have to study, come to the surface. They must say goodbye 

 for ever to the claims to certainty which they could make, so long as they 

 remained within the confines of their geometrical system. From being 

 one of the most exact, albeit narrowly circumscribed, sciences, economics 

 of necessity becomes one of the most conjectural. 



Yet the conjecture of the trained observer may be of value. In the 

 recent period economists have already offered advice on the basis of their 

 conjectures in this dubious field. To this department belong many of 

 the recommendations concerning control of the trade cycle ; they are 

 based on propositions concerning causal sequences not derived from the 

 Law of Demand : on propositions, therefore, which are to some extent 

 conjectural. Hence the recent conflict of prescriptions, of which we have 

 heard so much. Thus we may account for the transition from the 

 unanimity of advice, common in the last century, of which free trade is a 

 good instance, to present-day disagreements. The former was based on 

 the analytical map, making no claim to causal knowledge ; the latter is 

 based on the necessarily conjectural propositions of cycle theory, which 

 must make such a claim and are conjectural precisely because they entail 

 such a claim. 



But the new realm of conjecture, though it may drive out the old know- 

 ledge from its position of central interest in the economist's mind, does 

 not invalidate that knowledge. It will be a thousand pities if the con- 

 flicting nature of prescriptions of the new type, which economists are right 

 to give, albeit without claim to certainty, since they must give of their best, 

 undermines the authority of the advice given on the basis of the analytical 

 map. 



I now proceed to a more detailed examination. What remains is 

 divided into four parts. The first I call the economic criterion, which 

 deals with the nature and authority of the prescriptions given on the basis 

 of the analytical map. The second is the theory of value and distribution, 

 which considers the scope and validity of the causal knowledge derived 

 from the Law of Demand. There remain the recent strivings after causal 



