Full Idea
Though consciousness of what is past does ascertain our personal identity to ourselves, yet to say that it makes personal identity, or is necessary to our being the same persons is to say a person has not existed a single moment but what he can remember.
Gist of Idea
If consciousness of events makes our identity, then if we have forgotten them we didn't exist then
Source
Joseph Butler (Analogy of Religion [1736], App.1)
Book Reference
'Personal Identity', ed/tr. Perry,John [University of California 1975], p.100
A Reaction
An over-cautious scepticism has crept in about the reliability of bodily identity. Now we can have photographs and CCTV to prove that we experienced events we have forgotten. Butler is right.