Personal Identity and Memory, Part II: Triviality

In this earlier post, I tried to capture a broadly Lockean thought about the role of memory in personal identity in this principle:

(ID2) x is the same person as y iff x and y are persons [perhaps better: person stages]; and x can extend their consciousness back by having a memory of the form ‘I performed action or thought token a’, and y did in fact perform action or thought token a.

In the previous discussion, I began to ward off a threat of triviality, which I diagnosed as due mostly to the pernicious understanding of the phrase ‘criterion of identity’ as flagging a method of discovery of identity. (ID2) is pretty useless if one is trying to figure out whether x really had a memory when thinking ‘I performed action or thought a‘, since the evaluation of the personal indexical in that sentence is precisely what the issue of identity turns on.

Personal Identity and Memory, part I: some reflections on Locke

(This is the first part of a two three-part post on personal identity and memory. This part concentrates on Locke; the next part will look at the role of memory as a sufficient condition for personal identity; the final part will look at the infamous transitivity worries about memory-based theories of personal identity.)

Modern discussion of diachronic identity originates with Locke, who introduces many of the standard moves in the literature—for example:

• connecting identity with same-F-as, for any sortal predicate F;
• distinguishing the question of what it is to be an F at a time from the question of when an F picked out at one time is indeed the same F as another F picked out at another time;
• and noting that general bans on coincident entities must themselves be relativised to sortals: ‘whatever exists any where at any time, excludes all of the same kind, and is there it self alone. (Essay, 2.27.1—all future unattributed references are to the Essay).

This last point is important in some controversial issues. Lowe (1995: 106) for example argues that identity is ‘absolute’, and thus one object cannot be an instance of two distinct sortals with two different criteria of identity, so that—contrary to appearances—Locke is not actually allowing that there might be a man who is also a person. But if Lowe is right, then Locke needn’t have included the italicised qualification in the quote above; the fact that he does is some evidence that the natural treatment of the text is correct.