Until now, philosophical debate about human embryonic stem cell (hESC) research has largely been limited to its ethical dimensions and implications. Although the importance and urgency of these ethical debates should not be underestimated, the almost undivided attention that mainstream and feminist philosophers have paid to the ethical dimensions of hESC research suggests that the only philosophically interesting questions and concerns about it are by and large ethical in nature. My argument goes some distance to challenge the assumption that ethical considerations alone must be foregrounded in philosophical discussions about hESC research by introducing a critical stance on the epistemological and ontological assumptions that underlie and condition it. A central aim of the paper is to show how Foucault's insights into knowledge-power, taken in combination with Hacking's claims about styles of reasoning, can make these assumptions evident, as well as cast light on their potentially deleterious implications for disabled people. Arguing in this way also enables me to draw out constitutive effects of research on stem cells, that is, to indicate how the discursive practices surrounding research on stem cells, as well as the technology itself, contribute to the constitution of impairment.