This law is set forth in the third section of the third book (posthumous) of _Das Kapital_. A few criticisms have been made of it, which vary from that of Sombart, who says that it is developed _in the most striking manner_ (in glänzendster Weise), to that of Loria, who defines it as 'a metaphysical pistol shot (_sic_) from beyond the Rhine,' and thinks that he refutes it by an objection which is in fact quite inappropriate. Others have thought the law certainly true, but that it explained only partially the fact of the decline in the rate of profits and required to be combined with other laws already known to classical economics. But most of those who have studied Marx's economic theories have not examined it at all; his opponents (like Böhm Bawerk) reject it by implication, when they reject Marx's fundamental principles; the Marxians welcome it, German fashion, humbly and submissively, without discussion, with that lack of freedom and intellectual originality which is noticeable in all their writings. The examination of it attempted here, rests on the same basis as Marx's theories, _i.e._ it is made from the standpoint of those who accept the essentials of these theories, and hence the premiss of _labour-value_, the distinction between _fixed_ and _floating_ capital, the view of profits as arising from _surplus-value_, and of the _average rate_ of profits as arising from the equalisation, owing to competition, of the various rates of surplus-value. It is true that I accept all these things _in a certain sense_, which is not the sense of the ordinary Marxian, inasmuch as they are not looked upon as _laws actually working in the economic world_, but as _the results of comparative investigations into different possible forms of economic society_. But such a reservation, which relates to a question discussed by me at length elsewhere,[89] has practically no effect on the present study, whose results would be almost the same, even if these theories of Marx were interpreted in the sense which I consider erroneous. The object here is no longer to determine and define accurately Marx's fundamental concepts, but to see whether, from these concepts, even when interpreted in the current manner, it is ever possible in any way to deduce the _law of the fall in the rate of profits_. This task I think impossible.