occur if improvements in the productivity of labour in making producers’ goods kept pace with the productivity of labour in using producers’ goods to make consumers’ goods (capital-saving inventions balance labour-saving inventions, so that technical progress is ‘neutral’). However, we can easily get out of this difficulty by postulating that as a matter of fact technical progress is mainly labour-saving, or, a better term, capital-using, so that capital per man employed is rising through time.

Rosa Luxemburg treats the authors whom she examines in Section II with a good deal of sarcasm, and dismisses them all as useless. To some of the points raised her answers seem scarcely adequate. For instance, Rodbertus sees the source of all the troubles of capitalism in the falling proportion of wages in national income.[36] He can be interpreted to refer to the proportion of wages in gross income. In that case, she is right (on the assumption of capital-using inventions) in arguing that a fall in the proportion of wages is bound up with technical progress, and that the proportion could be held constant only by stopping progress. He can also be taken to refer to the share of wages in net output, and this is the more natural reading. On this reading she argues that the fall in share of wages (or rise in rate of exploitation) is necessary to prevent a fall in the rate of profit on capital[37] (as capital per man employed rises, profit per man employed must rise if profit per unit of capital is constant). But she does not follow up the argument and inquire what rise in the rate of exploitation is necessary to keep capitalism going (actually, the statisticians tell us, the share of wages in net income has been fairly constant in modern industrial economies[38] ). It is obvious that the less the rate of exploitation rises, the smaller is the rise in the rate of saving which the system has to digest, while the rise in real consumption by workers, which takes place when the rate of exploitation rises more slowly than productivity in the consumption good industries, creates an outlet for investment in productive capacity in those industries. The horrors of capitalism, and the difficulties which it creates for itself, are both exaggerated by the assumption of constant real-wage rates and, although it would be impossible to defend Rodbertus’ position that a constant rate of exploitation is all that is needed to put everything right, he certainly makes a contribution to the argument which ought to be taken into account.

Tugan-Baranovski also seems to be treated too lightly. His conception is that the rising proportion of constant capital in both departments (machines to make machines as well as machines to make consumers’ goods) provides an outlet for accumulation, and that competition is the driving force which keeps capitalists accumulating. Rosa Luxemburg is no doubt correct in saying that his argument does not carry the analysis beyond the stage at which Marx left it,[39] but he certainly elaborates a point which she seems perversely to overlook. Her real objection to Tugan-Baranovski is that he shows how, in certain conditions, capitalist accumulation might be self-perpetuating, while she wishes to establish that the coming disintegration of the capitalist system is not merely probable on the evidence, but is a logical necessity.[40]

The authors such as Sismondi, Malthus and Vorontsov, who are groping after the problem of equilibrium between saving and investment, are treated with even less sympathy (though she has a kindly feeling for Sismondi, to whom she considers that Marx gave too little recognition[41] ) for she is either oblivious that there is such a problem, or regards it as trivial.[42] We leave the discussion, at the end of Section II, at the same point where we entered it, with the clue to the inducement to invest still to find.

Section III is broader, more vigorous and in general more rewarding than the two preceding parts. It opens with a return to Marx’s model for a capitalist system with accumulation going on. Our author then sets out a fresh model allowing for technical progress. The rate of exploitation (the ratio of surplus to wages) is rising, for real wages remain constant while output per man increases. In the model the proportion of surplus saved is assumed constant for simplicity, though in reality, she holds, it would tend to rise with the real income of the capitalists.[43] The ratio of constant to variable capital is rising for technical reasons. (The convention by which the annual wear and tear of capital is identified with the stock of capital now becomes a great impediment to clear thinking.) The arithmetical model shows the system running into an impasse because the output of Department I falls short of the requirements of constant capital in the two departments taken together, while the output of Department II exceeds consumption.[44] The method of argument is by no means rigorous. Nothing follows from the fact that one particular numerical example fails to give a solution, and the example is troublesome to interpret as it is necessary to distinguish between discrepancies due to rounding off the figures from those which are intended to illustrate a point of principle.[45] But there is no need to paddle in the arithmetic to find where the difficulty lies. The model is over-determined because of the rule that the increment of capital within each department at the end of a year must equal the saving made within the same department during the year. If capitalists from Department II were permitted to lend part of their savings to Department I to be invested in its capital, a breakdown would no longer be inevitable. Suppose that total real wages are constant and that real consumption by capitalists increases slowly, so that the real output of Department II rises at a slower rate than productivity, then the amount of labour employed in it is shrinking. The ratio of capital to