In their book Identity, Personhood and the Law,1 authors Charles Foster and Jonathan Herring seek, among other things, to show that the law is based on overly simplistic assumptions about the nature of personal identity. In their Author Meets Critics précis, they summarise the main contentions of the book on this issue. Difficulties in the law’s simplistic approach are, they claim, exposed when we think about people with dementia, ‘where [in advanced cases] I may turn into a person with no apparent continuity at all with my own self’ and where:

X2 will simply inhabit a body composed of some of the same cells as belonged to X1.

Deep brain stimulation ‘may similarly transform ‘my’ attributes to such an extent that it seems false to continue to talk about ‘me’ at all.’ Other examples, including cases of patients suffering severe anorexia or who have fallen into a permanent vegetative state (PVS), are given. All of them ‘call into question the atomistic, billiard-ball model of identity used by the law and by our uninterrogated intuitions.’

The authors’ approach is to begin with these and a number of other examples and raise several philosophical and ethical issues. They then discuss the issues and develop principles which they apply to the same examples at the end of the book.

In this commentary, I cannot do justice to all the claims and challenges to the law the authors make in their rich and highly recommended book. I will focus only on the issue of personal identity and their remarks about the simplistic assumptions made by the courts on this issue. Although my comments will not always be in agreement with theirs, these remarks should be taken …