Persons

2. Persons and human beings

We must be clear about what is and what is not controversial in Locke’s view. It is not controversial that the features Locke cited (reason, reflection and so on) are central to our concept of a person. What has seemed controversial to some is the stronger claim that truths about the ontological status of persons (for example, that all persons are animals) are contingent. This stronger claim is denied by animalists. They hold that all persons must be animals. They do not hold that all persons have to be human beings – chimpanzees and dolphins, for example, could qualify as persons if their behaviour revealed a suitably impressive mental life.

This move away from the Lockean position is apt to seem unpersuasive. To start with, animalists can hardly be presenting their definition as an a priori conceptual truth. People who believe in the actual existence of non-animal persons (God, angels, souls and so on), or people who believe in the possibility of robot persons, do not appear to be committing any conceptual error. Further, the truth that I am a human being (or, more generally, an animal) seems resolutely a posteriori. Animalists must therefore conceive of their definition as a necessary a posteriori truth. And its source must lie in the further supposed truth that animality is a necessary a posteriori constraint on possession of the mental life which is characteristic of persons. But what reason do we have to believe this? As far as I can see, we have none.

More tellingly, the most plausible description of certain thought experiments counts against the animalist position. I can make perfectly good sense of the possibility that I might gradually become an entirely bionic being. My various bodily and brain parts may gradually be replaced by functionally identical bionic parts. Provided that the changes preserve my continuing mental life, abilities and appearance, we would have little hesitation in saying that I survived a process of total replacement. Yet, at the end of the process, I am not an animal of any sort. Consequently, it cannot be true that all persons must be animals. Hence, we have good reason to think that the truth that all persons are animals is merely contingent. In addition, we also have good reason to think that the relation between a person and the human being they share their matter with is not that of numerical identity. If I can survive the destruction of the human being with whom I am presently spatially coincident, I cannot be identical to that human being. The Lockean view has been vindicated.