Do findings in neuropsychology alter the philosophical understanding of the self?

The findings of neuropsychology have been widely taken up in 20th- and 21st-century philosophy and, in some cases, have also been the subject of controversial debate. In this context, the debate over whether there is an “authentic self” and an “identity” exist as phenomena of consciousness, how they can be defined, and what it means to be authentic and to remain “the same person”, has been conducted extensively in recent decades in the light of findings from neuropsychology. There is a vast body of literature on this subject, which I myself cannot fully survey. However, the outcomes of these discussions are by no means clear-cut and cannot be easily summarised.

Depersonalisation and derealisation as crisis-like experiences of consciousness

You ask specifically about depersonalisation and derealisation. In psychiatry, these terms refer to a disturbance of consciousness that can be triggered by severe psychological stress and trauma. According to a medical information website, this refers to

"a persistent or recurring feeling of being detached from one’s own body or thoughts (depersonalisation) and/or from one’s surroundings (derealisation)." (Source: MSD Manual)

So you are talking about a very specific, highly dramatic phenomenon – more precisely, a crisis-like experience of consciousness that can be unsettling and difficult to make sense of for those affected and those around them. Neuropsychology is unlikely to offer a better explanation for this either, even if evidence can be found in the brain that something is happening in various functional brain regions. The central question is – much as with dissociation: who is the real person? Must the person always be unified, coherent and continuous?

Or should we rather say that the real person consists of all the individual aspects that seem to diverge at certain moments? The phenomenon described as a ‘disorder’ may well be a defence mechanism – a way of being able to live with an otherwise unbearable trauma at all. Perhaps it is also a strategy employed by the self to ensure survival, so that the experience can be processed more effectively later on.

We are more than the surface of our consciousness.

To me, these phenomena clearly demonstrate that our notions of consciousness as a coherent stream that, like a river, always remains the same (even though the contents of the stream of consciousness – like the water in the river – are constantly changing) are far too simplistic. We are more than the surface of our consciousness. And what lies beneath is just as much a part of us. People who experience depersonalisation or derealisation undergo a rupture – but this rupture, too, is part of them. Although it is experienced as a rupture in identity, it is in fact part of identity itself.

Something similar might perhaps be said about the concept of an authentic self. Even without extreme experiences such as depersonalisation and derealisation, it is often not easy for us to determine what our authentic self actually is. We never fully understand ourselves. We are always an infinity. At the same time, we strive to be a reliable presence for others, someone they can trust. This task is a constant companion – sometimes in particularly challenging ways, making psychotherapeutic support necessary.