 Geach makes many interesting claims about the behavior of relative identity relations. For example, he claims that it is possible for a to be the same K as b, but not the same K*, where ‘K’ and ‘K*’ are sortal terms denoting distinct kinds. Take, for example, the Debtor’s Paradox. In that case, we have an earlier portion of matter, M1, and a later portion of matter M2. According to Geach, M1 is not the same portion of matter as M2, but it is the same person. In this way, he is able to allow for the persistence of persons through changes in parts. (See the entry on  relative identity  for more details.)