‘I’ve had many faces, many lives,’ says the Doctor in a trailer for the fiftieth-anniversary episode of Doctor Who. The Doctor has indeed had many lives, regenerating from peevish grandfather to quick-witted clown to impatient dandy, and so on, through to the awkward young man played by Matt Smith. This is, of course, a consequence of the need to recast the central character every few years, but, unlike other long-running series (such as the Bond movies), where the change of face goes unnoticed within the fictional world, Doctor Who has a fictional counterpart for recasting, regeneration. And because of this, the change can be a radical one, permitting the show’s creators to re-imagine the central character every few years and allowing new fans to develop an attachment to their ‘own’ doctor.
But regeneration is a strange notion. How can one person have many lives, especially as such different people? How is the situation different from one in which several distinct people succeed each other? Maybe regeneration kills the old Doctor and produces a completely new timelord who just thinks he’s the Doctor? We can ask similar questions about ourselves. We go through many changes in our lives, passing from child to youth to adult to pensioner. These transformations are not as dramatic as the Doctor’s regenerations, but they are major ones, and again we can ask why different life-stages are episodes in the life of a single person, rather than distinct people. This is the question of what philosophers call personal identity.
Most philosophers agree that the unifying factor is continuity of some kind, though they disagree as to what kind. On one view, bodily continuity is crucial: the pensioner’s body is a natural development of the bodies of the earlier stages. Another view focuses on psychological continuity: the pensioner’s mind is continuous with the minds of the earlier stages – they share memories and other mental states, and there are causal connections between their minds. On the first view, a person is essentially a body, on the second, essentially a mind. To test your intuitions on this, imagine a science-fiction mind swap. Suppose Jack’s mental states (memories, beliefs, desires, hopes, and so on) are temporarily transferred to Jill’s brain. Which would you say is the best description of the situation: that Jack has temporarily lost his mind (Jack being essentially a body) or that Jack temporarily has a different body (Jack being essentially a mind)?
How does this apply to regeneration? Well, if people are essentially minds, then it seems the Doctor does survive regeneration. His memories, beliefs, desires, and so on are transferred intact to the new body (allowing for temporary post-regeneration amnesia). However, if bodily continuity is what matters, then things are not so clear. What exactly happens during regeneration? Is the old Doctor’s body reorganised very rapidly, or is it obliterated and replaced with a new one? In the former case the new body is continuous with the old one, and the Doctor survives, but in the latter the Doctor dies and is replaced by someone else who thinks he is the Doctor. It’s not clear which interpretation is correct, especially as the regeneration effect has changed over the years. (Prior to the Doctor’s fourth regeneration, a replacement body followed the Doctor around for a while, in the guise of the Watcher.) Maybe the Doctor has survived some regenerations and not others.
Things get even more complicated when regeneration goes wrong. In the episode ‘Journey’s End’, the tenth Doctor undergoes an abortive regeneration that results in the creation of a duplicate Doctor, identical except for being angrier and lacking the ability to regenerate. This duplicate (now living in a parallel universe with Rose) is psychologically continuous with the tenth Doctor, and may be more similar to him than the eleventh Doctor is. So maybe he is the real Doctor, and Matt Smith has been playing an unwitting imposter?
If this isn’t enough, consider those occasions when two incarnations of the Doctor meet (as in the anniversary episode). How can two co-existing people be the very same person? They can’t both be the whole Doctor, as it were. One option is to think of the Doctor as the amalgam of all the different Doctor stages that exist at particular times. On this view the whole Doctor is a ‘spacetime worm’ that is spread out in the fourth dimension of time as well as in the three dimensions of space, and what exists at any given moment is just a thin slice of this worm. In multi-doctor stories the Doctor worm has coiled back on itself, and two different slices of it meet each other. This view is called four dimensionalism, and there are reasons for thinking that it is true of us too.
Of course, we don’t worry about these questions as we watch Doctor Who. We just accept the person on screen as the Doctor. But the fact that the show so vividly illustrates these (and many more) philosophical problems is another reason for loving it. And however puzzling regeneration is, it is a brilliant device for keeping the show fresh and preserving the air of mystery and unpredictability around its central character. As the show enters its second half-century, we fans look forward to discovering more of the Doctor’s faces and lives.
Visit Keith's website www.keithfrankish.com to explore more of the mind of a philospher.