【正文】 ly its general principles are those of free petition. Under these circumstances the study, as a first approximation, of a perfectly petitive system, in which the multitudinous degrees and kinds of divergences are eliminated by abstraction, is clearly indicated. The method is particularly indicated in a practical sense because our most important questions of social policy hinge directly upon the question of the character of the natural results of petition, and take the form of queries as to whether the tendencies of petition are to be furthered and supplemented or obstructed and replaced. That such a theoretical first approximation is indicated in a theoretical sense, that it is the natural logical way of going at the problem, conforming to the workings of our thought processes, is sufficiently evidenced by the fact that this is what economists have always in fact done, ever since there has been such a science or such a social system to be studied. They have, to be sure, been criticized for doing it, and severely. But in the present writer39。s judgment theorists of the past and present are to be justly criticized not for following the theoretical method and studying a simplified and idealized form of petitive anization, but for not following it in a sufficiently selfconscious, critical, and explicit way. In their discussions of methodology the historic economists have, indeed, been as clear and explicit as could be desired,*6 but in the use of the method as much cannot, unfortunately, be said. It should go without saying that in the use of the scientific method of reasoning from simplified premises, it is imperative that it be clear to the reasoner and be made unmistakable to those who use his work what his procedure is and what presuppositions are involved. Two supreme difficulties have underlain controversies regarding method in the past. The first is the strong aversion of the masses of humanity, including even a large proportion of scholars, to all thinking in general terms. The second difficulty, on the other side, is the fact referred to above, that the persons employing methods of approximation in economics have not themselves adequately and always recognized, and still less have they made clear to their readers, the approximate character of their conclusions, as descriptions of tendency only, but have frequently hastened to base principles of social and business policy upon very inplete data. The evil results of the failure to emphasize the theoretical character of economic speculation are apparent in every field of practical economics. The theorist not having definite assumptions clearly in mind in working out the principles, it is but natural that he, and still more the practical workers building upon his foundations, should fet that unreal assumptions were made, and should take the principles over bodily, apply them to concrete cases, and draw sweeping and wholly unwarranted conclusions from them. The clearly untenable and often vicious character of such deductions naturally works to discredit theory itself. This, of course, is wrong。 we do not allow perpetual motion schemes to discredit theoretical mechanics, which is built upon the assumption of perpetual motion at every stage. But in economics a distrust of general principles, fatal as it is to clear thinking, will be inevitable as long as the postulates of theory are so nebulous and shifting. They can hardly be made sufficiently explicit。 it is imperative that the contrast between these simplified assumptions and the plex facts of life be made as conspicuous and as familiar as has been done in mechanics. The present essay is an attempt in the direction indicated above. We shall endeavor to search out and placard the unrealities of the postulates of theoretical economics, not for the purpose of discrediting the doctrine, but with a view to making clear its theoretical limitations. There are several reasons why the approximate character of theoretical economic laws and their inapplicability without empirical correction to real situations should be especially emphasized as pared, for instance, with those of mechanics. The first reason is historical and has already been indicated. The limitations of the results have not always been clear, and theorists themselves as well as writers in practical economics and statecraft have carelessly used them without regard for the corrections necessary to make them fit concrete facts. Policies must fail, and fail disastrously, which are based on perpetual motion reasoning without the recognition that it is such. In the second place, the allowances and corrections necessary in the case of theoretical economics are vastly greater than in the case of mechanics, and the importance of not losing sight of them is correspondingly accentuated. The general principles do not bring us so close to reality。 there is a larger proportion of factors in an economic situation which are of the variable and fluctuating sort. Again, in spite of the greater contrast between theory and practice in the study of the mechanics of petition, as pared with the mechanics of matter and motion, the contrast is less familiar and more easily overlooked. Our race has been observing and handling in a rude way the latter type of phenomena ever since it has lived on the earth, while petitive relations among men were established only a few generations ago. In consequence the habit of clear thinking according to scientific method, the use of hypotheses and separation of fundamental principles from the accidents of particular instances, has bee in some measure built up in the minds of at least a respectable body of the more cultivated division of the race. Perhaps it is even in some degree instinctive in certain strains.*7 Finally, it ma