Written partly in response to Social Darwinism and in particular to Thomas H. Huxley's Nineteenth Century essay, "The Struggle for Existence," Kropotkin's book drew on his experiences in scientific expeditions in Siberia to illustrate the phenomenon of cooperation. After examining the evidence of cooperation in nonhuman animals, "savages," "barbarians," in medieval cities, and in modern times, he concludes that cooperation and mutual aid are as important in the evolution of the species as competition and mutual strife, if not more so.
Although mostly supportive of Kropotkin's work, evolutionary biologist Stephen Jay Gould offers two criticisms.
Firstly, Gould points out that Kropotkin commits "a common conceptual error in failing to recognize that [Darwinian] natural selection is an argument about advantages to individual organisms". It would be many years before authors such as Richard Dawkins elicited a mechanism whereby genes might replicate at the expense of individual organisms.
Gould also argues more generally against sociobiology, insisting "there are no shortcuts to moral insight" and that the answers to such questions must be found within us, not in nature.