Length and the memory theory of personal identity

1. That there is an entity that is 25 inches long in 1973 and 72 inches long in 1993 is not even partly grounded in facts about anybody’s memory.

2. If the memory theory of personal identity is true, the existence of such an entity is at least partly grounded in facts about my memory.

3. So, the memory theory of personal identity is false.

Premise (1) is a raw appeal to intuition.

Premise (2) follows from the following:

1. Normally an existentially quantified fact is grounded in each of its instances.

2. I was 25 inches long in 1973 and 72 inches long in 1993.

3. I was a person.

4. The case at hand is a relevantly normal case.

I suppose the memory theorist just needs to deny (1).