To clarify this point, it may be noticed that the special cases in question are also precisely those where J. B. Clark's old model of "aggregate" marginal productivity holds strictly true, leading to equality between the equilibrium levels of the real wage rate and labour's aggregate marginal product, a hypothesis regarded as disproved by all sides during the Cambridge capital controversy. One would thus have a "pure" state of capitalist society where Marx's exploitation theory and its main supposed confutation were both true.