What is a Person?

For centuries it was generally accepted that the terms 'person' and 'living human being' were virtually equivalent. But over the last two decades, a number of influential modern philosophers, including Peter Singer, Jonathan Glover and John Harris, have challenged traditional understandings of personhood. As we will see, this has led them to some startling conclusions.

For Peter Singer a person is a being who has a capacity for enjoyable experiences, for interacting with others and for having preferences about continued life. For John Harris a person is any being who is capable of valuing their own life.

Once this kind of definition is accepted, there are a number of logical implications. Firstly it is immediately obvious that in order to be regarded as a person, you must have an advanced level of brain function. In fact you must have a completely developed and normally functioning cerebral cortex. 

Secondly, there must be a significant group of human beings who are non-persons. These include fetuses, newborn babies and infants who lack self awareness, and a large group of children and adults with congenital brain abnormalities, severe brain injury, dementia and major psychiatric illnesses.

Thirdly, there are many non-human beings on the planet who meet the criteria of persons. These include at least chimpanzees, gorillas, monkeys and dolphins, but may also include dogs, pigs and many other mammals. In fact it has even been argued that within the foreseeable future some supercomputers may meet the criteria to be regarded as persons.

Those who meet the criteria of persons have moral rights and privileges. They deserve to be protected from those who would injure or kill them. They should be allowed to exercise their own choices or autonomy as much as possible. But the same rights and privileges do not extend to non-persons. Peter Singer puts it like this, 'only a person can want to go on living, or have plans for the future, because only a person can understand the possibility of a future existence for herself or himself. This means that to end the lives of people against their will is different from ending the lives of beings who are not people…killing a person against his or her will is a much more serious wrong than killing a being who is not a person.' In other words killing a chimpanzee is a much greater moral evil than killing a newborn baby or an adult with Alzheimer's disease.

When people respond with incredulity, Singer argues that to make moral distinctions on the basis of species is to be guilty of a new crime, 'speciesism'. Instead we should make moral distinctions on the basis of 'ethically relevant characteristics', such as the ability to choose and value your own life.

Of course there are major logical problems with this kind of definition of personhood. In effect Singer has replaced one form of discrimination with another. Instead of discriminating on the basis of species, he is now arguing that we should discriminate on the grounds of cortical function. In fact if we are into name-calling we could call him a 'corticalist'. But why should corticalism be preferable to speciesism? Of course Singer may wish to argue that cortical functioning is 'ethically relevant' whereas species membership is not. But this is an arbitrary distinction that is hard to defend on entirely logical grounds. Why should the functioning of a 5mm layer of neurones be the central and only moral discriminating feature between beings? On purely logical grounds species membership is a more coherent and fundamental basis for making ethical distinctions between beings. 

  What is a Person? John Wyatt