Abstract

Contrary to Sankey’s central assumption, incommensurability does not imply incomparability of content, nor threaten scientific realism by challenging the rationality of theory comparison. Moreover, Sankey equivocates between reference to specific entities by statements used to test theories and reference to kinds by theories themselves. This distinction helps identify and characterize the genuine threat that incommensurability poses to realism, which is ontological discontinuity as evidenced in the historical record: Successive theories reclassify objects into mutually exclusive sets of kinds to which they refer. That is why claiming that scientific progress is an increasingly better approximation to truth is difficult to justify. Similarly, Sankey’s attack on neo-Kantian antirealist positions is based on his misunderstanding of some of the central terms of those positions, making most of his attack on them ineffectual, including his diagnosis of their incoherence. We conclude by reiterating our conviction that in this debate meta-incommensurability plays an important role.Keywords: Scientific realism; Incommensurability; Meta-incommensurability; Thomas Kuhn; Paul Feyerabend; Howard Sankey.