 So Kim and Bickle draw the modus tollens conclusion, and insist that these neuroscientific successes are evidence that psychological kinds are not as widely or as radically multiply realized in brains as many functionalists and nonreductive physicalists assume. It turns out that even celebrated neural plasticity is systematic within and across nervous systems. It has a regular progression following damage to a principal structure; there are underlying neural mechanisms that subserve it, evolutionarily conserved across species. Furthermore, the newly realized function following brain damage is typically seriously degraded compared to initial performance. Persons can still talk, manipulate spatial representations, or move their extremities, but their performances are typically qualitatively and quantitatively worse than normals. This fact gives rise to tricky questions about individuation of psychological function. Are these alternative neural structures realizing the same psychological function, the same mental kind, as before, as the philosophical uses of multiple realizability require? (This last response has been further developed more recently; see  §2.4  and  §3.1  below.)