In Chapter 14 Marx gives variations on the theme:
“The same factors that bring about a fall in the general rate of profit provoke counter effects that inhibit this fall, delay it and in part even paralyse it. These do not annul the law but they weaken its effect. […] The law operates therefore simply as a tendency, whose effect is decisive only under certain particular circumstances and over long periods” (346).
We can immediately note that there are not parallax lines determining the development of capitalism, but instead a single line that may either cause the profit rate to fall or to cause it to increase. This single line is labour productivity: how much of a given market can be held with the least investment in labour-power? The increase in labour productivity both leads to the decline n the rate of profit and the increase in the mass of profit. Given the interaction of different industries, labour productivity can increase the rate of profit by decreasing the value of constant capital, particularly, but also variable capital.
The other element is the notion of causality. The effect of the law is only decisve given that certain particular circumstances operate temporally. A set of circumstances must be given for the law to be an effect instead of a tendency. This complicates the idea of labour productivity itself being the motor of capital accumulation; even if it is the determining factor in Marx’s law of the fall in the profit rate.
Marx’s insists that even if the law is paralysed it is not annulled. What does that mean?
In Chapter 13 he notes that:
“The progressive tendency of the general rate of profit to fall is, therefore, just an expression peculiar to the capitalist mode of production of the progressive development of the social productivity of labour. This does not mean to say that the rate of profit may not fall temporarily for other reasons. But proceeding from the nature of the capitalist mode of production, it is thereby proved a logical necessity that in its development the general average rate of surplus-value must express itself in a falling general rate of profit” (319, translation modified)
What Marx claims to have proved is not that the profit rate will fall, but that its fall is a logical necessity given the model of capitalism he has developed. The rate of profit may fall ‘for other reasons’. If the law of the fall in the profit rate is a logical necessity within the model Marx has developed – and the purpose of Capital is only to develop such a model, or a way of thinking capital – then a law for Marx is a logical implication of a set of ‘particular circumstances’ or conditions. The law of the fall in the profit rate is conditional and not absolute.
Perhaps we can say that instead of Marx making a claim that the profit rate will fall, he is claiming that it will given conditions x, y, and z. The purpose of the argument about declining profit rates goes to the dynamism of capital – not its inevitable collapse. A declining profit rate in one industry leads capital to other industries; and decline in the social rate of profit leads to innovating capitals out competing older capital’s with Robert Brenner’s sunk capital.
Marx gives variations on the following comment on crisis through these chapters, this instance from Chapter 15:
“Crises are never more than momentary violent solutions for the existing contradictions, violent eruptions that re-establish the disturbed balance for the time being” (357).
In the Marxism we receive from the 20the Century, crisis was supposed to be some end point of capital accumulation. Here Marx is saying that they are momentary and that re-establish accumulation. Capitalism develops through crisis, they do not end it in any way. In fact, it is arguable that without crisis it would break down; but this thought is really unthinkable: the concept of capitalism requires the sub-concept of crisis.