It’s an interesting subject, and my only hesitation comes from the reason I’ve been invited, which is in effect to discuss the question as it applies to the human body, from the point of view of my own experience of being trans. The trouble is, the more I think about it the less the Theseus’s Ship paradox seems to have to do with trans experience (or at least mine), even though questions of change and continuity are clearly involved.
Actually, I think it's an odd question to address to trans people more than anyone else, because the bodily changes that (may) accompany transition aren’t really that great – even if they’re important to us. In a purely physical sense they’re probably less radical than, say, the loss of a foot; but someone who lost their foot would be most unlikely to be asked on to a radio programme to discuss whether they're still the same person, etc. Of course, I know that we are all in a continual process of bodily change, but that is no more true of trans people than anyone else.
On the other hand, I’ve had more than one dismaying and upsetting conversation in which people close to me have told me that I have become, in their eyes, a different person. This baffled me at first. My personality seemed to me the same: I had the same memories, the same tastes in books and music and food, the same habits, the same hobbies, the same sense of humour, the same interests. I hadn’t undergone any major personality shift, as far as I could see. Of course, it wasn’t that nothing had changed, but from my point of view there was an an overwhelming degree of continuity between me-before and me-after, and any change was well within the “normal limits” of major life events (bereavement, having a child, emigrating) that happen to people all the time without their being told that they are no longer the same person. At first, I was at a loss to explain it. It would be easy to say that these people were being superficial, and judging me by outward appearances – by which toilet I used, or which clothes I wore. But I knew they were not superficial people.
But I think there’s another way of looking at it – and here I must turn to my day job for an analogy about genre. The study of genre involves noting the formal and thematic qualities of texts (a sonnet has fourteen lines, a romance ends with a couple getting together, etc), but it also involves appreciating how readers use assumptions about genre to navigate their way through a text and to provide ways of framing meaning.
When I teach genre I often get students to look at Thurber’s short story “The Macbeth Murder Mystery”, in which a young woman reads Macbeth under the impression that it's an Agatha Christie-style murder mystery, and tries to work out who “really” killed Duncan. Most people read Macbeth knowing in advance that it’s a tragedy, and so they’re primed to understand it in that light. The tragic aspects are highlighted, and other things are marginalized. The woman in Thurber’s story reads the same words in the same order, but she reads them within a different generic frame, and in that reading it’s the murder mystery aspect that get highlighted: she’s looking for clues, for suspects, for red herrings – and naturally she finds them. So, has she read the same text?
I think coming out as trans can be a bit like this. You’re not saying “I’ve changed”, or even "I was trapped in the wrong body, and now I'm busting out!" so much as “You’ve been reading me using the conventions of one genre/gender, but I need to be read as another.” It’s so much not that you have changed fundamentally (the words in the book are still there in the same order), as that the significance people place on you has done, and in the light of that you may indeed seem to them to be a different person – as different as an Agatha Christie is from a Shakespeare tragedy.
Of course, it’s more complicated than that, not least because you are reading yourself as much as anyone else is reading you; and you’re influenced by their readings too, which may be very powerful and persuasive; and (like everyone) you are changing in some ways, for example in response to the changes in the way you are treated by others. There are innumerable feedback loops in play, and circles both vicious and virtuous. The major stresses involved in transition are also likely to bring out some uncharacteristic behaviour. But even taking all that into account, I think the genre analogy may help explain the contrast between my own perception of continuity and the perception of radical change that some others have had. It's also one reason why it’s often been those who know me less well who have found it easier to accept my transition. It isn't simply that they aren't as involved with me emotionally; it’s also (and to an extent this may be another way of saying the same thing) that they have less invested in a particular reading.
ETA: This programme will broadcast at 3.00pm on 7th August. I think the recording went okay, but it depends how they edit it...
ETA: And here's the link to the broadcast programme. I'm ten minutes in.