I’m dealing with delusions in a current lawsuit (was a particular dead woman’s believe a delusion or not), and that has entailed a great deal of reading to prepare for trial. A delusion is basically a persistent belief held without or even contrary to evidence.

While not directly relevant to my case, one type of delusion which makes frequent appearance in literature and movies is the “delusional misidentification syndrome” here someone believes others are replaced with an imposter (and now that robots are crossing the “uncanny valley” this might even become possible); that the person in the mirror is an imposture, that someone else has been doubled or tripled, that I have been doubled:

Intermetamorphosis is a misidentification syndrome in which an individual has the erroneous belief that familiar persons have exchanged identities. In the syndrome of subjective doubles, patients believe that there are other persons who look like them, but that they have different traits and live different lives. This situation has been commonly depicted in movies, such as The Sixth Day,9where Arnold Schwarzenegger’s character is cloned without his knowledge or consent, and in TV shows, such as Battlestar Galactica10 and Star Trek,11 where clones represent the main rivals to the shows’ heroes. Mirrored-self misidentification involves the misperception that one’s reflection in the mirror is a stranger. Individuals affected with the syndrome of delusional companions believe nonliving objects possess consciousness, can think independently, and feel emotion. The movie Night at the Museum12 features objects exhibited at a museum that appear alive to the protagonist. Clonal pluralization of the self differs from the syndrome of subjective doubles, in that the patient believes that there are multiple copies of himself who are physically and psychologically similar to themselves.

The Masks of Identity For all this strangeness, misidentification syndromes entail not believing that either oneself or another is the person they appear to be.

For example, a man named Arthur, following an automobile accident believed that his parents had been replaced with impostors. His father set up a means of responding this delusion:

The next day, Arthur’s father entered his son’s bedroom and announced cheerfully, “Arthur, guess what! That man you’ve been living with all these days is an impostor. He really isn’t your father. You were right all along. So I have sent him away to China. I am your real father.” He moved over to Arthur’s side and clapped him on the shoulder. “It’s good to see you, son!”

Arthur blinked hard at the news but seemed to accept it. When he came to our laboratory the next day I said, “Who’s that man who brought you in today?”

“That’s my real father.”

“Who was taking care of you last week?”

“Oh,” said Arthur, “that guy has gone back to China. He looks similar to my father, but he’s gone now.”

Alas, this intellectual acceptance of his parents did not last. One week later Arthur reverted to his original delusion, claiming that the impostor had returned.

Arthur was suffering from Capgras’ delusion, one of the rarest and most colorful syndromes in neurology. The patient, who is often mentally quite lucid, comes to regard close acquaintances – usually his parents, children, spouse or siblings – as impostors. Although such bizarre delusions can crop up in psychotic states, more than a third of the documented cases of Capgras‘ syndrome have occurred in conjunction with traumatic brain lesions, like the head injury that Arthur suffered. This suggests to me that the syndrome has an organic basis. But the majority of Capgras’ patients are dispatched to psychiatrists, who tend to favour a Freudian explanation of the disorder.

The Unbearable Likeness of Being, The Independent November 22, 1998.  The how and why of these delusions are the subject of great debate. The “Masks of Identity”, cited above, lists out of the various potential causes and treatments; but there is no universal consensus.

As a psychiatric condition, it is unimaginably sad. How can love and friendship exist, where those closest to one (the delusions seem to center upon those closest; although there are delusions about those who are not close in fact, such as believing a famous person is in love with me) may not be “real.”

What the delusions do raise is questions about what constitutes a “self”. The question seems obvious — even silly to ask: of course I know who I am and who you are. But when we begin to specify precisely what makes one-self consistently the same, problems arise.

If we merely limit it to the body, why do we hold someone in prison for more than a few years? If all of the cells in the body have been replaced, then the original person no longer exists. If self is a matter of behavior, then is an actor the same person? If self is a matter of self identification (which is a common delusion at present), then if someone self-identifies as someone different today than they were yesterday, has someone new taken over the same body?

And so, when we trace out the radical self-identification chic of our present, it becomes increasingly difficult to distinguish it from delusion.