Postscript: sortal concepts are fundamental for tracing identity

Our discussion with Rips, Blok, and Newman (2006; Blok, Newman, & Rips, in press; Rhemtulla & Xu, in press) has brought together theory and evidence from researchers in adult cognition and those in infant development. By this point, researchers all recognize that any theory of concepts of individuals must consider the evidence from infants' first concepts as well as explicit adult reasoning tasks. Despite this agreement, we continue to disagree on several fundamental issues.