 Whether one accepts the “shifty” view of memory or not, the debate is important to opening up different interpretations of the slow switch thought experiment. For it complicates what effect the slow switch has on Oscar’s conceptual repertoire. The default view is that the slow switch causes Oscar’s water concept to be wholly replaced by the twin water concept. But it may be unclear why a slow switch destroys Oscar’s water concept, even as he becomes acquainted with twin water (Boghossian 1989; 1992a, Gibbons 1996, Burge 1998). More discussion of the issue is found in the supplementary document,  Variations on Slow-Switching.