thesis

he shares Swinburne’s views on the indivisibility of the self. Nonetheless, his interpretation
undermines Swinburne’s argument – if there is no evidence to suggest that the right hemi-
sphere is conscious then the “person” in Swinburne’s thought experiment would simply
follow wherever the left hemisphere went.
Sperry, however, sees the right hemisphere as (1974)
a conscious system in its own right, perceiving, thinking, remembering, reasoning, willing,
and emoting, all at a characteristically human level… though predominantly mute and gener-
ally inferior in all performances involving language or linguistic or mathematical reasoning…
On this issue, epistemic difficulties seem insurmountable. If we cannot ask the right
hemisphere whether it is conscious, how are we to know? Nevertheless, even if we grant
Swinburne’s claim that we create “two separate living persons”, why should we not con-
clude that neither of the two persons is the same as the one before? If each hemisphere of the
brain is specialised for certain forms of processing, surely the phenomenology of each will
lack part of what used to make up that of the original connected brain. The left side may no
longer appreciate music, and the right side will be incapable of conversation. It seems
doubtful that each would “behave as if he had p’s character” as Swinburne suggests.
Swinburne is ready to accept the possibility of this account but his argument takes an
epistemological turn (150–1):
Even if this notion of partial survival does make sense, it will in no way remove the difficulty,
which remains this. Although it may be the case that if my two brain hemispheres are trans-
planted into different bodies, I survive partly as the person whose body is controlled by one
and partly as the person whose body is controlled by the other, it may not be like that at all…
Knowledge of what has happened to a person’s body and its parts will not necessarily give
you knowledge of what has happened to the person… so… persons are not the same as their
bodies… It suffices to make my point to point out that the mere logical possibility of a person
surviving with only half his brain (the mere fact that this is not a self-contradictory supposi-
tion) is enough to show that talk about persons is not analysable as talk about bodies and their
parts.
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