2 th - century theories of personal identity particles that make up the organism and whose activities constitute a biological life – there are on this view no brains, and hence no thinking brains 10. The ontological problem Again, friends of the psychological-continuity view must deny that we are animals But even more fundamentally, several writers have argued that it is difficult to find any sensible view of what we are – any sensible answer to question (c) in section 1 – that sits well with the psychological-continuity view (Olson 1994; 2007; van Inwagen 1997; 2002; see also Merricks 1999) Suppose first that “three-dimensionalism” is true: things exist at different times by being wholly present at each of those times, not by having temporal parts; as it is often put, things endure through time What kind of enduring thing am I, if the psychological-continuity view is true? The brain may seem to be a natural candidate (despite the abovementioned attempts to deny its existence), as it is responsible for a person’s mental features; again, in the Brownson case, Brown’s psychology goes where his brain goes In fact, however, psychological continuity – even non-branching psychological continuity – is not necessary and sufficient for a brain’s identity over time It is not necessary, for my brain existed before it had any capacity to sustain mental features; and it may lose that capacity without ceasing to exist Furthermore, consider a so-called “brain-state transfer” case (Shoemaker & Swinburne 1984, 108–111): a machine records information about the total physical state of Brain A, located in Room A, then erases it; it also erases the total physical state of Brain B, located in Room B; then it produces Brain A’s state in the brain located in Room B After this procedure, the brain in Room B is psychologically continuous with Brain A as Brain A was before the transfer (insofar as brains have mental features at all; but that is assumed by the proposal at issue, since we have mental features), not with Brain B as it was before the transfer Crucially, the brain located in Room B after the transfer is manifestly Brain B: its mental features have gone, but it has not gone anywhere Hence, Brain B has persisted through psychological discontinuity This also shows that psychological continuity is not sufficient for a brain’s identity over time For, obviously, the brain-state transfer does not result in Brain A becoming identical with Brain B No process can have such a result, for nothing can become identical with anything other than itself It would not be reasonable to reply that what really happens in this case is that Brain A is in fact transferred to Room B and becomes composed of the particles that a moment earlier composed Brain B (which ceased to exist when its state was erased) Surely no brain can instantaneously change its location without any of its proper parts having moved from the one location to the other.17 A popular view is that persons are (enduring entities and) “constituted” by animals (Baker 2000; Shoemaker 1984): I am composed of the same particles as the animal in my chair and occupy the same place as it, but we have different modal 141