Plutarch wrote the "Life of Theseus" in the late 1st century in which he described that a ship carrying Theseus had returned from Crete to Athens and was preserved by Athenians over a period of time. During that period planks decayed and had to be replaced and eventually the entire ship was replaced. So the question was raised: Is it the same ship since the entire ship has been replaced?
Several centuries later Thomas Hobbes came along and asked: What if the original planks were gathered up after they had been replaced and they were used to construct a second ship exactly as the original one? Does this ship become the original Ship of Theseus? And, if the replacement ship Plutarch described had attained designation as the Ship of Theseus, are there now two Ships of Theseus or does just one become the Ship of Theseus? Which one? Of course, it is possible that one might think that neither ship qualifies as the Ship of Theseus. So we are faced with the question: What constitutes what a 'thing' is?
Not long after Hobbes, David Hume was reflecting on this question in relation to what constitutes a person. Hume felt that even though we have changed over a period of time, we still think we are the 'same person'. This troubled Hume. He divided the issue into the 'features of a person' and the mysterious "self" that supposedly possesses those features. This enabled him to observe that "we are never intimately conscious of anything but a particular perception; man is a bundle or collection of different perceptions which succeed one another with an inconceivable rapidity and are in perpetual flux and movement". This has become known as the "Bundle theory of self". For Hume, identity did not reside in some enduring core substance, but in a composition of different, related, yet a constantly changing bundle of elements. (It should be noted that Hume was not satisfied with this characterization, but never returned to the issue.)
More recently, Daniel Dennett has proposed that the self is not some sort of physically detectable entity, but a convenient fiction which he likens to the notion of a center of gravity. He describes the center of gravity as a fictional location that enables the description and solution of certain problems, as in the center of gravity of a hoop is a point in thin air. For Dennett, people devise stories to make sense of the world and, in those stories, they, themselves, are a central feature, but their position as a central feature is only a convenient fiction like the center of gravity. Not surprisingly this has become known as "Self as a center of narrative gravity" thesis. (http://ase.tufts.edu/cogstud/papers/selfctr.htm) The point of Dennett's thesis is that there is not just one 'self' inhabiting the individual entity, but a multitude of 'selves' and to identify one particular 'self' as "The Self" is simply a matter of convenience.
Given that I have condensed 2500 years of consideration of the self into just four possible perspectives, what do you think? Is there a 'central core' we can identify as the Self? If so, how can we do so? If not, then are we reduced to notions like the Hume's bundle of perceptions or Dennett's center of narrative gravity? Are we left with the conundrum of what constitues the Ship of Theseus and thus what constitutes a Self? And, if we are to accept that there is no 'core self' but a multitude of 'selves', how can we assert the notion of free will as a given when we cannot even be certain that the 'self' supposedly possessing the 'will' is, in fact, a constrained or unconstrained self?
Well, one of my selves has just surfaced to suggest that the recent self has had the floor long enough and it is time to for one of the other selves to assume center stage. I hope this "recent self" is able to return to center stage in time to share your thoughts on the issue this coming Sunday. At any rate one of my selves will be there. I'd say, "See you then", but I can't be sure which self is saying it and which self will be showing up to see you there. Sigh...life used to be so simple.