Defending Robustness: The Bacterial Mesosome as a Test Case

In “Facts, Artifacts, and Mesosomes: Practicing Epistemology with the Electron Microscope” (1993), Nicolas Rasmussen presents an account of the mesosome, a bag-shaped membranous structure first observed by electron microscopists in grampositive bacteria, as a test case for robustness. Rasmussen argues that robustness as a criterion for the reality or artifactuality of experimental results fails this test; for, after 15 years of interpreting electron micrographs of specimens prepared by a variety of techniques as supporting evidence for the existence of mesosomes, electron microscopists ultimately concluded that mesosomes were an artifact produced by these preparation techniques. According to Rasmussen, electron microscopists did not use robustness to “decide reliably between conflicting observations” (ibid., 231). Moreover, Rasmussen also claims that research on mesosomes “resembles that of high flux gravity waves as described by Harry Collins, especially in the obviousness of ‘experimenter's regress’ or logical circularity entailed in the evaluation of experiments according to their results…“(ibid., 256).