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Chapter 8 Personal Identity |
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continued, Section 2 of 4 Second Criterion: Continuity
Continuity may well be another
necessary condition of personal identity. Generally speaking, continuity
is the property of being unbroken, or whole, over time. Solid
inanimate objects exhibit this property because they retain the same atoms
in the same relative positions over time. With living things,
continuity becomes more complex. Locke starts his Essay with a definition of continuity in vegetable life:
We must therefore consider wherein an oak differs from a mass of matter, and that seems to me to be in this, that the one is only the cohesion of particles of matter any how united, the other such a disposition of them as constitutes the parts of an oak; and such an organization of those parts as is fit to receive and distribute nourishment, so as to continue and frame the wood, bark, and leaves, etc., of an oak, in which consists the vegetable life. That being then one plant which has such an organization of parts in one coherent body, partaking of one common life, it continues to be the same plant as long as it partakes of the same life, though that life be communicated to new particles of matter vitally united to the living plant....[12] So, by Locke, a plant may replace individual
particles without violating its identity. Only the greater living
structure must persist over time.
This truth of
vegetable continuity would seem to be a truth of animal and human continuity as
well. Harold Noonan develops the idea in his survey of personal identity
philosophy. He speaks here of "bodily identity," but continuity
of the human body over time is implied:
The most natural theory of personal identity, which would be almost anyone's first thought, is that personal identity is constituted by bodily identity: P2 at time t2 is the same person as P1 at time t1 if and only if P2 has the same body as P1 had.... According to this view personal identity is essentially no different from the identity of material objects in general. An artefact, like a ship, or a living thing, like an oak tree or a horse, persists through time. Its persistence does not consist in its retention of the same matter — for artefacts can be repaired and patched up and living things are necessarily involved in a constant exchange of matter with their environment — but in its retention of the same form as its matter undergoes gradual replacement....[13] Sydney Shoemaker[14] and Derek Parfit[15] refine this position, concluding that the brain is
the only organ of the human body for which continuity is
necessary. Noonan distills the essence of their theories:
"P2 at time t2 will be the same person as P1 at time t1 just in case P2 at t2 has the same brain [emphasis added] as P1 at t1."[16] Shoemaker and Parfit have made some
assumptions about brain function, but the assumptions are reasonable. This
essay has already presented evidence of brain function which justifies their
claims.
Continuity would appear to be a
protean property of material objects, one expressed in several modes
by inanimates, plants, animals and human beings.
 Second
Conclusion: The continuity criterion of personal identity has a
corporeal basis.
next Section 3 of 4 |
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Chapter 8, Section 2 Endnotes |
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[12] Locke 330-31, Chapter 27, Section 4.
[13] Noonan 3.
[14] Sydney Shoemaker,
Self-knowledge and
Self-identity (Ithaca: Cornell University Press, 1963) 22-25.
[15] Derek Parfit, Reasons and Persons
(Oxford: Clarendon Press, 1984) 253.
[16] Noonan 5.
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Copyright © 1999
Wayne Stewart
Last update 4/19/11