Functionalism and Personal Identity
Agar (Nicholas)
Source: Nous, Mar2003, Vol. 37 Issue 1, p52-70, 19p;
Paper - Abstract

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Philosopher’s Index Abstract

  1. Examines the relationship between personal identity and functionalism1.
  2. Synchronic and diachronic unity;
  3. Marker of copersonality.

Author’s Introduction
  1. Is there any more to a person's survival2 or identity3 over time than the persistence of her memories, desires, and other mental traits? According to what I will call the psychological view about persons there is not. This view finds most forceful contemporary expression in the psychological continuity4 theories (henceforth PCT) of Derek Parfit5, Sydney Shoemaker, and John Perry. These writers take stories about psychological mergers, divisions and body swaps to show that continuities of memory, belief, and desire are all that should count toward judgments about survival.
  2. Some attack the PCT by rejecting the broader psychological view about survival. They argue that information about mental state scan only have evidential status in questions about the persistence of individuals. If I began as a non-psychological foetus6 or soul and may one day survive in a beliefless and memoryless coma, then I must be separable from my memories and beliefs.
  3. Rather than challenging the translation of questions about identity into questions about minds, my strategy will be to argue that the PCT is founded on mistaken views about mental states. I will defend an alternative, functionalist expression of the psychological view, which I suggest has implications for personal identity significantly divergent from those endorsed by the PCT.
  4. Do we have reason to think that any psychological theory, functionalist or otherwise, will point to sufficient facts to decide questions about identity? A fashionable relativism about personal identity allows that though psychological information may constrain judgments about identity it cannot fully determine them. Advocates of this view argue that we must look to local cultural factors to work out which of the humanly viable physical continuity7 or psychological continuity8 theories is true of us. Against the relativists I claim that a functionalist psychology points us toward all the identity or survival determining facts we could want. Relativism about personal identity will require a rather more extreme relativism about functionalist psychology.
  5. So, how is the functionalist to find identity facts? I argue that a functionalism about what unifies a person's mental states at a particular time leads to a functionalism about what unifies them over time. This suggestion will not be entirely unfamiliar to followers of the personal identity debate. Many writers have speculated about the connection between the synchronic and diachronic unities of mental states, and Sydney Shoemaker goes so far as to make the connection between functionalist accounts of both dimensions of unity in arguing for the PCT. I will use the famous teletransporter9 thought experiment10 to help show that a functionalism about identity or survival points away from the PCT. Functionalism does not, as Shoemaker thinks, permit survival by teletransportation11 or by brain state transfer12. Indeed, the expression of psychological view described here will come rather close to agreeing with the rival physical continuity13 theory on the conditions under which a person survives.


See "Shoemaker (Sydney) - Functionalism and Personal Identity - a Reply" for Shoemaker's reply.

In-Page Footnotes

Footnote 3:
  • Many philosophers distinguish the more practical issues identified by the question 'what matters in survival?' from the metaphysical question about necessary and sufficient conditions for survival.
  • My immediate concerns are metaphysical, but what I have to say will have bearing on the practical question.
  • By arguing that the metaphysics of survival rules out survival by teletransportation, I shall also be claiming that what matters in survival is not carried over.
  • For stylistic reasons the words 'identity' and 'survival' will be used interchangeably throughout this paper.

Text Colour Conventions (see disclaimer)

  1. Blue: Text by me; © Theo Todman, 2020
  2. Mauve: Text by correspondent(s) or other author(s); © the author(s)

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