The Human Animal, Personal Identity Without Psychology, Eric T. Olson
Oxford University Press, New York, 1997, pp.189
ISBN 0-19-510506-0
Although Darwinian explanatory strategies are being employed ever more widely, in areas as diverse as
culture and cosmology, there remains a widespread reluctance to subscribe to a central tenet of
Darwinism, namely the thesis that we ourselves are animals. This reluctance does not, for the most
part, stem from a belief that we are immaterial souls, but from a doctrine about objects and their identity
conditions. We may be wholly material beings, but are nonetheless material beings of a distinctive sort,
namely persons. Whereas animals have biological identity conditions, persons have mentalistic identity
conditions, from which it follows that persons and animals are numerically distinct. The Human Animal
is a vigorous and sustained assault on this way of thinking. Olson’s main claim is that the Lockean or
“Psychological Approach”, irrespective of how it is developed in detail, is metaphysically flawed, and
he urges us to accept in its stead a Biological Approach, according to which we human persons are
organisms of a particular kind, members of the biological species Homo sapiens, entities whose
persistence conditions are entirely independent of mentality.
I will come to Olson’s intriguing metaphysical arguments shortly, but I want to comment first
on another aspect of his position, which is also of interest. The Psychological Approach is inspired by
imaginary cases in which psychological and physical continuity come apart. Olson’s favoured scenario
of this sort, tailor-made to mesh with his account of the persistence conditions of organisms, is based on
the supposition that our mental states and capacities are located in the upper parts of the brain, the
cerebrum, which is surgically separable from those parts of the lower brain responsible for autonomic
bodily functions. If the Biological Approach were true, cerebrum transplants would have no more
affect on personal identity than kidney transplants, but this seems absurd. Wouldn’t it be reasonable for
you to care about the person who receives your cerebrum (and so your psychology) in just the ways that
you would care about your future self? Wouldn’t it be right and reasonable for your friends and family
to do likewise? Given the strength of intuitions such as these, isn’t it clear that personal identity and
psychological continuity are inseparable? Some opponents of the Psychological Approach hold that
these patterns of personal concern are misguided, but Olson adopts a different tack. In a Parfitian spirit,
he accepts that it may well be that psychological continuity is what matters, practically and prudentially,
but points out that for this to count against the Biological Approach we would need to be sure that the
relationship which matters - call it M - always coincides with identity. But doesn’t the fission case (on
one interpretation at least) demonstrate that identity and M can come apart? Perhaps cerebrum
transplants are another instance of the same divergence.
This is an ingenious manoeuvre, and a radical one, but I am not convinced it is enough to
undermine the attractions of the Psychological Approach. Irrespective of what a biologist or surgeon
might make of a cerebrum transplant, what would a psychologist make of it? From the latter vantage
point there is surely a case for saying that a distinctive kind of entity, a mind, is transferred from one
animal to another. Many philosophers will want to say the same. Given this, the rationale of the
Psychological Approach remains intact: if we equate persons with (usually embodied) minds, we can
take our prudential and practical personal concerns to be what they seem to be, i.e. concerns for
persons, or selves.
At this point Olson’s metaphysical arguments become relevant. Olson attacks the
Psychological Approach from a number of angles, but I will concentrate on the main line of argument,
which first surfaces in chapter 4. A young human foetus does not possess any psychological capacities,
and so cannot be psychologically continuous with any later being. If personal identity requires
psychological continuity, it follows that none of us were ever foetuses. Olson argues that this result is
as problematic as it is surprising. If the foetus from which I developed was never a person, what
happened to it when I appeared on the scene? The idea that it ceased to exist is implausible, since a
foetus is an animal, and animals do not die when they develop nervous systems. But if we concede that
the foetus remains in existence, and follow the Psychological theorist in maintaining that the foetus is
distinct from the person, we are committed to saying that when a foetus develops to a certain stage, “the
atoms which make it up begin to compose something else as well, a second being; and that thing is the
person. You, the person, now share your space and matter with a human animal”. Is this not an
absurdity? If I share all my matter and physical characteristics with an animal, how could I fail to be an
animal?
In reply, the Psychological theorist can appeal to the widely accepted doctrine that material
objects can materially coincide yet remain numerically distinct provided they possess different modal
and/or historical properties. Since the persistence conditions associated with the sortals “person” and
“animal” are different, each can survive changes that would be fatal to the other. Isn’t this enough to
secure their numerical distinctness? Olson attacks this position in chapter 5. He points to a tension
between the Psychological Approach and the Lockean view of what counts as a person. According to
the former, the animal with which I materially coincide is not a person because it has the wrong
persistence conditions, but it also seems that the very same animal satisfies the Lockean criterion for
personhood: doesn’t the animal have exactly the same mental capacities that I do? It seems that if we
accept the Lockean criterion, what we ordinarily take to be one person is really two. If we deny that the
animal is a person on the grounds that it has the wrong persistence conditions, we are hardly any better
off: we now have an account of personal identity which only applies to half the world’s population of
conscious intelligent beings. Moreover, if the possession of conscious intelligence does not suffice to
make something a person, how can any thinking being know that it is itself a person? Olson sees only
one escape route for the Psychological theorist: could it be that we are animals who have psychological
persistence conditions? Perhaps, but he makes a convincing case against this option, and so concludes
that the Psychological Approach is untenable, and the Biological Approach unavoidable.
This conclusion needs qualifying, for Olson makes it clear at the outset that his objections to
the Psychological Approach are directed at those who share his basic metaphysical assumptions:
persons really do exist, persons are wholly material beings, identity is not relative, and concrete
substances are not extended through time. Although dualists, relativists and four-dimensionalists can
handle the relationship between persons and animals with comparative ease, and so may well take
encouragement from Olson’s arguments, these doctrines face problems of their own, and many find
them unattractive.
Olson’s general objection to the Psychological Approach, variants of which have been
propounded by Ayers and Snowdon, is not a new one, but Olson gives it several new twists and wields
it effectively. In its original guise, the objection was directed at Locke’s claim that persons could be
distinct from the immaterial substances which possessed their mental capacities, an odd idea indeed,
and one which Chisholm mocked thus: “If I want my dinner, does it follow that two of us want my
dinner? Or does the thinking substance want its dinner and not mine?”. Restricting our attention to the
person-animal relationship, there are a number of ways to meet the “too many thinkers” objection.
Burke has recently developed a theory of substances and sortals which fits the bill, as has E.J. Lowe.
Although proposals such as these are themselves controversial, Lockeans can draw some comfort from
Olson’s concluding line: “There are no easy solutions”. Alternatively, they might want to consider a
simpler reply, which limits the force of the objection, and suggests some weaknesses in Olson’s overall
strategy.
Olson assumes the Psychological theorist is obliged to say that animal and person wholly
coincide, but this assumption is questionable. If the relevant mental capacities are grounded in only a
small part of the animal, and this small part is, at least in principle, detachable from the remainder, then
can we not say the following. Yes, animals have mental capacities, but strictly speaking, the whole
animal does not possess these capacities, only a part of the animal possesses them; so in saying that
“Animals have mental capacities”, what we are really saying - or would say on reflection - is that
“Animals have mental capacities by possessing a part which has these capacities”. Since (proper) parts
are numerically distinct from their wholes, if we associate persons with the relevant parts, the claim that
we are animals is undermined. Consider an analogy. On noticing that your new cooker has a clock
built into it, you remark “My new cooker can tell the time”. But a friend objects: “How can this be?
The clock in your cooker can tell the time as well, and can do so when removed from the cooker, so if
your cooker can tell the time, it seems there are two timekeepers where we know there is only one.” I
think it is clear what you would say to clarify this situation, but is the situation with animals and their
mental capacities very different? It might be objected that part of an animal cannot be a person because
persons are substances, not parts of substances. But this objection presupposes that the only natural
kinds are biological kinds (or substances), and so begs the question. A reply along these lines does not
establish that we are distinct from our cerebrums, and anyone who wishes to maintain that we are will
have to find a different way of solving the “too many thinkers” problem, but it does pose a problem for
Olson’s main line of argument, which (arguably) combines a biological bias with an overly narrow view
of the way animals and persons might be related.
The book as a whole is admirably succinct, clear, and forcefully argued, and is a fresh and
enjoyable read. It also contains a number of arguments I have not mentioned. Although some of these
struck me as being less potent than the argument discussed above, they are far from negligible - though
I did at times wonder how the author intended to reconcile his hostility to coincident entities with his
commitment to Wiggins’ account of substance concepts. And, lest I leave the wrong impression, the
book is not entirely negative: chapter 6 introduces a provocative proposal concerning the persistence
conditions of organisms. Those who have long harboured suspicions that the Psychological Approach
has problems of an ontological sort will welcome it; those who are sympathetic to this Approach can
look forward to encountering some interesting challenges, and some awkward moments.
Barry Dainton
University of Liverpool