The rare condition known as dicephalus occurs when (prior to implantation) a zygote fails to divide completely, resulting in twins who are conjoined below the neck. Human dicephalic twins look like a two-headed person, with each brain supporting a distinct mental life. Jeff McMahan has recently argued that, because they instance two of us but only one animal, dicephalic twins provide a counterexample to the animalist's claim that each of us is identical with a human animal. To the contrary, I (...) argue that in cases of dicephalus it is obvious neither that there is one animal nor that there are two of us. Consequently, the animalist criterion does not straightforwardly apply to cases of dicephalus. I defend an account of dicephalus that is both sensitive to the complexity of twinning phenomena and not inconsistent with animalism. In my view, dicephalic twins are a borderline case of the concept HUMAN ANIMAL. I conclude with some speculative remarks concerning the normative import (if any) of my claim that dicephalic twins are a borderline case. (shrink)

What is it for a thing to be dead? Fred Feldman holds, correctly in my view, that a definition of ‘dead’ should leave open both (1) the possibility of things that go directly from being dead to being alive, and (2) the possibility of things that go directly from being alive to being neither alive nor dead, but merely in suspended animation. But if this is right, then surely such a definition should also leave open the possibility of things that (...) go directly from being dead to being neither alive nor dead, but merely in suspended animation. I show that Feldman’s own definition of ‘dead’ (in terms of ‘lives’ and ‘dies’) does not leave this possibility open. I propose a new definition that does. (shrink)

Part of the appeal of the biological approach to personal identity is that it does not have to countenance spatially coincident entities. But if the termination thesis is correct and the organism ceases to exist at death, then it appears that the corpse is a dead body that earlier was a living body and distinct from but spatially coincident with the organism. If the organism is identified with the body, then the unwelcome spatial coincidence could perhaps be avoided. It is (...) argued that such an identification would be a mistake. A living organism has a different part/whole relationship and persistence conditions than the alleged body. A case will be made that the concept ?human body? is a conceptual mess, vague in an unprincipled manner, and that an eliminativist stance towards dead bodies is the appropriate response. (shrink)

One reason why the Biological Approach to personal identity is attractive is that it doesn’t make its advocates deny that they were each once a mindless fetus.[i] According to the Biological Approach, we are essentially organisms and exist as long as certain life processes continue. Since the Psychological Account of personal identity posits some mental traits as essential to our persistence, not only does it follow that we could not survive in a permanently vegetative state or irreversible coma, but it (...) would appear that none of us was ever a mindless fetus. But what happens to the organism that was a mindless fetus when the _person_ arrives on the scene?[ii] Can the acquisition of thought destroy an organism? That would certainly be news to biologists. Does one organism cease to exist with the emergence of thought and another organism, one identical to the person, take its place? (Burke,1994) That doesn’t seem much more plausible than the previous move. Should identity and Leibniz. (shrink)

Scott Campbell has recently defended the psychological approach to personal identity over time by arguing that a person is literally a series of mental events. Rejecting four-dimensionalism about the persistence of physical objects, Campbell regards constitutionalism as the main rival version of the psychological approach. He argues that his "series view" has two clear advantages over constitutionalism: it avoids the "two thinkers" objection and it allows a person to change bodies. In addition, Campbell suggests a reply to the objection, often (...) raised against views such as his, that thoughts must be distinct from their thinker. In this paper, I argue that Campbell's responses to the "two thinkers" and the "thoughts/thinker" objections are unsuccessful. Furthermore, his reply to the latter leads to four-dimensionalism of the kind he wanted to avoid – and this view too allows a person to change bodies. Moreover, I argue that it speaks against the series view that generalised versions of it fare much more poorly than do generalised versions of constitutionalism and four-dimensionalism. (shrink)

The philosophical problem of personal identity starts with something like Descartes’ famous question—“But what then am I?”—construed as an inquiry into the most fundamental nature of creatures like us. Let us stipulate that creatures like us are most fundamentally persons. That is, ‘person’ is the name of our..

If we are neither animals nor material things constituted by animals, we might be parts of animals. This chapter is devoted to the view that we are spatial parts of animals; the next asks whether we are temporal parts. The only spatial parts of animals that I can think of any reason to suppose we might be are brains, or something like brains--parts of brains or perhaps entire central nervous sytems. Call the view that we are something like brains the (...) brain view. (shrink)

The apparent fact that each of us coincides with a thinking animal looks like a strong argument for our being animals (animalism). Some critics, however, claim that this sort of reasoning actually undermines animalism. According to them, the apparent fact that each human animal coincides with a thinking body that is not an animal is an equally strong argument for our not being animals. I argue that the critics' case fails for reasons that do not affect the case for animalism.

Most philosophers writing about personal identity in recent years claim that what it takes for us to persist through time is a matter of psychology. In this groundbreaking new book, Eric Olson argues that such approaches face daunting problems, and he defends in their place a radically non-psychological account of personal identity. He defines human beings as biological organisms, and claims that no psychological relation is either sufficient or necessary for an organism to persist. Olson rejects several famous thought-experiments dealing (...) with personal identity. He argues, instead, that one could survive the destruction of all of one's psychological contents and capabilities as long as the human organism remains alive--as long as its vital functions, such as breathing, circulation, and metabolism, continue. (shrink)

I argue that it is possible for a human animal to survive the loss of all bodily parts other than the brain.

The paper is concerned with how neo-Lockean accounts of personal identity should respond to the challenge of animalist accounts. Neo-Lockean accounts that hold that persons can change bodies via brain transplants or cerebrum transplants are committed to the prima facie counterintuitive denial that a person is an (biologically individuated) animal. This counterintuitiveness can be defused by holding that a person is biological animal (on neo-Lockean views) if the “is” is the “is” of constitution rather than the “is” of identity, and (...) that a person is identical with an animal in a sense of “animal” different from that which requires the persistence conditions of animals to be biological. Another challenge is the “too many minds problem”: if persons and their coincident biological animals share the same physical properties, and mental properties supervene on physical properties, the biological animal will share the mental properties of the person, and so should itself be a person. The response to this invokes a distinction between “thin” properties, which are shared by coincident entities, and “thick” properties which are not so shared. Mental properties, and their physical realizers, are thick, not thin, so are not properties persons share with their bodies or biological animals. The paper rebuts the objection that neo-Lockean accounts cannot explain how persons can have physical properties. To meet a further problem it is argued that the biological properties of persons and those of biological animals are different because of differences in their causal profiles. (shrink)

I go deep into the biology of the human organism to argue that the psychological features and functions of persons are realized by cellular and molecular parallel distributed processing networks dispersed throughout the whole body. Persons supervene on the computational processes of nervous, endocrine, immune, and genetic networks. Persons do not go with brains.

My comments have two parts. I begin by laying out the argument that seems to me to be at the core of Olson’s thinking about human persons; and I suggest a problem with his reasons for accepting one of its premises. The premise is warranted by its platitudinous or commonsensical status; but Olson’s arguments lead him to conclusions that undermine the family of platitudes to which it belongs. Then I’ll raise a question about how Olson should construe the vagueness that (...) would seem to infect the boundaries of human animals. (shrink)