 Malthus granted in principle that measures like contraception could prevent the increase in population that reduces standards of living to the subsistence level but he held out little hope. Lange was more sanguine, but the positive note in his book may have come too late to prevent its opening chapters from ensuring its unpopularity. The talk of the struggle for existence, and the rigid-sounding laws that govern it, could hardly have been inspiring to the workers’ movement it was meant for (Mehring 1960, 352). Nonetheless, Lange did not draw the conclusions from Darwin that the social Darwinists did. He did not take Darwinism as supporting capitalism, in part because he took it to be a mistake to straightforwardly infer any normative conclusions from the Darwinian explanatory claims: “Where Darwinism assumes that gross changes can be explained in terms of the ‘summation of slight individual variations’ over millennia, Lange suggests that this will not suffice as an all-purpose explanatory framework. In some cases, he thinks, it is necessary to appeal to organisms’ capacity to initiate rapid, deliberate change” (Clarke 2021, 299). In keeping with this critical perspective, Lange seemed to regard the principles appealed to in Darwin and Malthus as natural tendencies that could be mitigated by human reason. These explanatory laws do not determine how we should think, nor do they determine how we must inevitably think: