Animals, humans and personal identity

Clara asked:

Can animals be considered persons?

What do philosophers supporting bodily continuity in terms of personal identity argue and how can I reject their arguments?

Answer by Jürgen Lawrenz

Clara, these are great questions, touching on the most fundamental issues that philosophy can deal with! However, in many ways both of them address the same underlying problem, and so I will deal with them together.

But I must begin with a caveat. Not all philosophers who wrote on these matters were au fait with biology. E.g. John Locke was a medico in an era of practically zero neurophysiological knowledge, so we must disqualify his pronouncements on two souls in one body and two bodies sharing a soul. Similarly some present day conjectures try to fit digital ideas onto living processes and let their fancies outrun biological capacities. I shall ignore them too.

The basics of this matter turn on the possession of language and a conceptual faculty. These two features enable human self-reflexivity, i.e. our consciousness of individuality and the ability to frame mental artefacts which we call ‘concepts’. Animals don’t have this capacity, even though all mammals (e.g. dogs, horses, apes, dolphins) possess a neocortex. This makes it doubtful whether or not they have a sense of individuality, or ‘personhood’. Many handlers of such animals believe it to be the case, as they feel that some forms of intimate communication between them is possible. However, there is no known method of clinching such arguments, in the main because animals have extremely limited resources of articulation.

On the other issue, matters are considerably more involved. The strongest arguments for the life-long persistence of personhood are Kant’s ‘Unity of Apperceptions’ and Schopenhauer’s ‘Principle of Individuation’. These and similar propositions can be questioned on the basis of pathological disruption of personality. E.g. someone may suffer coma, severe psychological trauma or complete memory loss and in some cases start a new life after the restoration of their personality. Whether these patients are identical with their former selves is perhaps debatable, but there are two main arguments against the supposition of a new identity.

The first is, that the notion of personhood is intrinsically ill-defined, as a five-year-old child is hardly a formed personality and must add character traits aplenty in their future life — in other words, personality is not a thing and cannot be pinned down to a single coherent phenomenology. Therefore loss or change of personality are undeniably possible.

The other objection is, that a person’s body and life form one indissoluble entity. The notion of personal identity is therefore bound up with the autonomy of living processes, in which all mental processes are included. Therefore a unique personhood is a subjective conscious self-reflectivity that can indeed change without annulling objective personhood.

In sum, the stronger battalions are on the side of the uniqueness and persistence of personhood in life. Disruption and change may alter its qualitative features, but not its intrinsic continuity. From a neurophysiological point of view, it can be said that much empirical evidence collected from brain damaged patients points to the brain’s capacity to restore its own integrity (in some cases despite catastrophic pathology), which seems to provide pretty conclusive evidence in favour of continuity.

Incidentally, the first empirical case study is the story of Phineas Gage, who survived a 4-foot-long iron rod being driven through his head. It changed his personality, but he remained the same ‘person’ for the 12 years of his post-trauma life. Look him up in the web!

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