Thomas Reid (1710 - 1796) Defender of Commonsense Realism
Locke: “strange consequence” 1 Locke says: “personal identity…consists in consciousness alone…. So that whatever has the consciousness of present and past actions is the same person to whom they belong. SO: Many intelligent beings may be same person, and conversely. (369)
Locke: “strange consequence” 2 i) At time T2 person P remembers T1; SO (P at T2) = (P at T1). ii) At T3 person P remembers T2; SO (P at T3) = (P at T2). iii) So (P at T3) = (P at T1) from i and ii and [transitivity of identity]. iv) But at T3 P has irrevocably forgotten T1. SO: (P at T3) ≠ (P at T1) which contradicts iii. [reductio ad absurdum]
First objection (369) For Locke: “consciousness [is] confounded with memory.” [consciousness ≠ memory, but Locke confuses the two, and treats them as if they were the same] Locke says our consciousness reaches to past, but we are not conscious of the past, we merely remember it.
Second objection (369) For Locke: “personal identity is confounded with the evidence we have of person identity” Argument: the case of the stolen horse Similarity is evidence of identity, but identity does not consist in similarity. horse identity ≠ evidence for horse identity
Third Objection (370) Consciousness continuously changes, but personal ID does not. “Identity [through time] can only be affirmed of things that have a continued existence. [But] Consciousness and every kind of thought are transient and momentary.” SO: Personal ID does not consist in [ ≠ ] consciousness.
Fourth Objection (370) Locke “confounded [confused] that sameness or identity which we ascribe to an individual [numerical or strict identity] with the identity which, in common discourse, is often ascribed to many individual of the same species [qualitative identity].” [Note: same as 2 nd Objection?]
Fourth Objection (continued) One person cannot experience the [numerically identical] pain of another, no matter how similar their two experiences may be [even if qualitatively identical]. SO [qualitative] similarity of remembered experiences from one day to the next does not entail [numerical/strict] identity.
Parting Shot “As our consciousness sometimes ceases to exist, as in sound sleep, our personal identity must cease with it. Mr. Locke allows that the same thing cannot have two beginnings of existence, so that our identity would be irrecoverably gone every time we ceased to think, if it was but for a moment.”
Is Reid right? Two questions: 1. Is Locke’s theory of Personal ID wrong? 2. If it is wrong, should we - cling to commonsense with Reid Person has “continued existence” [strict identity] through time? - abandon [strict] Personal ID altogether? - develop new theory of Personal ID?