Referring to Francis Bacon's 17th-century definition of modern science as the conquest of nature "for the relief of man's estate," Kass looks with concern at the ironic possibility that future advances in medical science and technology may lead to the significant diminishing of humankind. Thus he asks, what price will we wind up paying for medical progress? Kass is concerned about the disconnect between modern medicine, with its powers to extend our controls over life and death and over many human potentials, and, on the other hand, traditional social and individual values.

He argues particularly for serious consideration of values in three areas: (1) distributive justice (which for Kass is, finally, the question as to who shall do the distributing), (2) the "use and abuse of power" (in which he focuses on the process by which power over nature becomes turned into power of some humans over others), and (3) "voluntary self-degradation and dehumanization" (two major concerns being the concept of the optimum baby and the development of technologies of pleasure).