Dr Jekyll's theory of consciousness

30 March 2005

One issue raised by Gregg Rosenberg (see below) is that of Multiple Personality Disorder, or Dissociative Identity Disorder (DID), as it is now known. He uses it merely to support his case for the conceivability of co-existing but distinct identities, but it is a large, interesting, and unclear subject in itself; and the idea of multiple identities fits very nicely with theories of consciousness based on the "pandemonium" model, in which a number of agents or "demons" compete to determine the contents of consciousness.

DID has always been a controversial subject. Although there is an extensive literature and there have been a huge number of cases, it is still quite possible to disbelieve in it more or less completely. Actually, that requires some qualification. It really depends on what you think the phenomenon of multiple personalities amounts to. I see three main possibilities:

• the patients in question really have more than one separate person operating independently within a single brain;
• they merely believe they have more than one personality;
• they systematically maintain an elaborate pretence of having more than one personality.

Even the last of the alternatives constitutes an interesting psychological phenomenon, whose existence it would be hard to deny. Of course there is also a fourth, psychologically uninteresting category, consisting of those who systematically maintain the appearance of multiple personalities, not out of some obscure internal motivation, but in order to evade punishment, perpetrate fraud, or for other culpable but entirely normal motives. It is possible, prima facie, that there are real examples of cases falling into each of the four categories. People being the ambiguous creatures they are, the borderline between the second and third categories may be blurred, with patients who sincerely believe in their own multiplicity but occasionally help the evidence along a bit: and philosophers like Daniel Dennett , in the pandemonic tradition, would probably suggest that the distinction between the first and second category is not as sharp as we might have thought.

As it happens, Dennett, with Nicholas Humphrey, undertook an investigation of the DID phenomenon back in the late eighties, attending the Fifth International Conference on Multiple Personality/Dissociative States. An article for the New York Review of Books was apparently deemed not sceptical enough for publication there; eventually published elsewhere, it was included in Dennett's 1998 collection 'Brainchildren'.

It's easy enough to see why Dennett might find DID an intriguing possibility: on his view the content of consciousness is the result of competition between multiple drafts; why shouldn't alternative drafters occasionally seize control and produce deviant versions of their own? But Dennett and Humphrey did not paint an uncritical picture of the conference. They noted the campaigning zeal which many of the delegates displayed, and the competitive boasts made by therapists about the performances of their patients. Some of the claims made across the dinner table apparently included accounts which any dispassionate scientist would find hard to accept: patients whose eyes would change colour when a different personality took charge; a woman who was sterilised under one personality but became pregnant while controlled by another. Dennett and Humphrey noted that delegates whose research seemed unimpeachable were nevertheless tolerant towards colleagues whose claims and methods seemed less credible, and remarked that they themselves found they almost automatically went along with the claimed multiplicity when talking to patients who switched from one persona to another in mid-conversation.

Ultimately they considered that DID was a real clinical syndrome - though it was not clear how much of a role the therapists might play in shaping it or even bringing it about. This concern - that the doctors might be prompting patients to display dissociative symptoms - is a recurring one in this area. They noted that the number of cases was rising steeply - 200 up until 1980, 1,000 in treatment by 1984, 4,000 at the time of publication (there may have been ten times that number before the end of the century), and asked - where was all the multiplicity in earlier periods?

In fact, DID has a slightly longer history than Dennett and Humphrey seem to have realised. Until the great upsurge in the late twentieth century, the number of cases seems to have been highest between the mid-nineteenth century and the first two decades of the twentieth. Both the beginning and the end of this earlier phase are interesting.

It has been plausibly suggested that the idea of multiple personality only emerged in the early nineteenth century when demonic posession (real demons in this instance) ceased to be a phenomenon which educated opinion (especially that of doctors) could regard as scientifically tenable. It is certainly true that posession by devils, dybbuks, and the like shows some marked similarities with DID, although there are perhaps differences, too. Modern DID patients often seem to slip from one personality to another relatively easily - even unnoticeably - while my impression is that diabolical posession was a much more traumatic business and less easily revoked. Possibly this reflects the change in social attitude: whereas the victim of posession was in for probable exorcism at best and possibly burning at the stake, DID patients, happily, face no such dangers and perhaps don't need to struggle so hard.

Prima facie, of course, it's quite possible that historical cases of posession were in fact DID; in principle it's equally possible that DID is simply a new form of posession by more subtle and mendacious demons. Perhaps in a less repressed and more secular society the devils don't have to struggle so hard, either. Joking apart, I think there can be little doubt that moving from an inexplicable spiritual phenomenon to one which was in principle susceptible to medical intervention represented an important advance: it also allowed the pervasive sense of evil attached to posession to be put on one side. 

This sense of evil is very explicitly set out in the fictional work which, like it or not, hovers in the background of all these discussions. The Strange Case of Dr Jekyll and Mr Hyde first appeared in 1886 - which means it cannot be regarded as the source of the whole phenomenon, neat as that theory might be. Dr Jekyll believes all men are dual in nature: in fact, foreseeing the eventual advent of theorists like Dennett he says:

"I hazard the guess that man will be ultimately known for a mere polity of multifarious, incongruous and independent denizens."

It so happens, however, that Jekyll's own transformation takes place along moral lines. Since he happens to be impelled by wicked motives at the moment of taking his potion, Mr Hyde is the purely evil facet of his personality: a relatively small part of the composite Jekyll, he is also physically smaller (so much for a mere change of eye colour!) but gradually threatens to take over (not entirely, or not unambiguously, against Jekyll's will).

Given such deep roots and such a potent literary expression, one might wonder why the incidence of multiple personality ever faltered: but in fact it did fall during the early part of the twentieth century.One possible factor is a growth in awareness around that time of the need for therapists to exercise care in the way they handled patients, leading to fewer cases in which the disorder was evoked rather than discovered. Perhaps more significant is the emergence of new theoretical approaches; Freudianism, for example, offered an alternative approach to the analysis of mental illness which probably led practitioners away from diagnosing dissociation quite so widely. Particularly significant was the growth of schizophrenia as a diagnosis.

That, of course, opens up a new range of issues. The cause of schizophrenia is notoriously a subject on which many diverse theories have been proposed; but the definition of the condition also remains a matter of controversy: it has even been suggested that the term 'schizophrenia' does not, in fact correspond to any consistent and distinct psychological condition.