 Since, as Dummett argues (in a point further developed in Lowe 1989 and Wiggins 2001), proper names and sortal terms must be associated with a criterion of identity that determines the conditions under which the term may be correctly applied again to one and the same thing (1973 [1981], 73–75), we may use the associated criteria of identity in order to distinguish categories of objects referred to. All of those names and general sortal terms (usable in forming complex names) that share a criterion of identity are said to be terms of the same category, even if the criteria of application for the associated sortals vary (1973 [1981], 546). Thus, e.g., the sortal terms ‘horse’ and ‘cow’ (similarly, names of horses and cows) are terms of the same category, since they share the identity criteria suitable for animals.