THE SHIP OF THESEUS

My dear, perceptive reader, this post, as it takes shape in my mind, promises to differ from all the previous ones in that while all that came before dealt with very generalized situations, this one is on a very specific little thought nagging my consciousness, the philosophy and ethics behind the practice that is as of now still confined to the realm of science fiction, the Brain Transplant.

Also, I humbly beg you to forgive me for my use of the all too powerful and all too widely used tool of analogy. I resort to this because it is far too uncomfortable for me to present the arguments of which I as yet have only a dim view, using living, breathing human beings as subjects.

Fortunately, philosophy proposes a ready analogy in the form of an age-old legend and thought exercise, that of the Ship of Theseus. Plutarch put the story thus;

The ship wherein Theseus and the youth of Athens returned [from Crete] had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalareus, for they took away the old planks as they decayed, putting in new and stronger timber in their place, insomuch that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.

The question is obvious; the ship has been overhauled many times over; at what point, if at all, does it cease to be the original ship on which Theseus sailed?? If every part of the original ship was replaced in the name of repair, is it still the same? And if now, the parts which were replaced were used to build another ship, which is the ‘true’ ship of Theseus?

As one can no doubt imagine, there are many, many ways in which this particular thought exercise could proceed, and many different answers. Aristotle and his causes by themselves give a multitude of ‘solutions’, which, in my opinion are no more than a hopelessly tangled web. Consider, merely for the sake of argument, the Aristotelian ‘Formal Cause’, or the form/design of the object. Using this, it is clear that the ship is the same, as its design as not been altered, merely the materials used for the form. Batting for the exact opposite is the ‘Material Cause’, or the substance of the object. Here, the ship of Theseus loses identity with every overhaul, because the particular components are altered. However, one can also see that the ship loses its identity completely on the very first overhaul, rather than it being a gradual process.

Do you see what I mean, my dear reader? Already, we run into a mass of contradictions and puzzles. Also is the concept of ‘Final Cause’, which depends exclusively on the function of the object, or what it was intended for. Thus, even though the material of the ship changes, its purpose, viz. transporting Theseus, remains intact, and thus, the ship is the same. We run into more quagmire when we explore ‘Efficient Cause’, which focuses on the mode of creation of the object. Here, it is obvious that the solution would depend on the choice of craftsmen and artisans/

The problem is obviously one of identity, or sameness. Is something which is space extensive and time variant, ever the same at two different point in time? Hmmmm.. the preceding statement sounds like something out of a relativity textbook, doesn’t it? But wait, perhaps relativity can provide a resolution. Perhaps we could use the concept of a four dimensional existence to provide some light. An object is, after all, merely the aggregate of an infinite number of 3-D time slices. So, my argument runs thus, while there are no two identical time slices of the Ship of Theseus, the ship as a 4-D object is still the same. Now, I am the first to admit that the above doesn’t make much sense to intuition, but it is a possible solution, nevertheless.

Leaving the ship aside, let us return to the main question. In a brain transplant, whose identity is passed on to whom? I.e. say, if X’s brain is removed from his body, as he was in an irreversible vegetative state, and put into the brain dead Y, what would you address the result of the surgery as?? X? Y? Perhaps a combination, XY?? Or, perhaps, a completely new person, Z? The answer obviously depends on what you consider to be the identity of the person. But then, why would you consider a persons identity to be his brain, rather than his body, or vice versa?? The identity, that which makes X, X, is obviously not localized, but a composite, in which case, you come back to the exercise of the Ship of Theseus.

Two examples which spring to mind instantly are R. Daneel Olivaw of Isaac Asimov’s Foundation and Robot series’ , who, in Foundation and Earth says, “over the thousands of years of my existence, every part of me has been replaced several times, including my brain, which I has carefully redesigned six times, replacing it each time with a newly constructed brain having the positronic pathways containing my then current memories and skills, along with free space for me to learn more and continue operating for longer.”, and Marvin of H2G2 by Douglas Adams, who faces a similar situation.(with the exception of the diodes down his left side, of course, one of the standing jokes of the series)

You see, even science fiction is not completely comfortable with the concept of a human brain transplant, mainly, I bellieve, because of the problems outlined above. To you, perceptive reader, I leave the rest. Speculate to your hearts content, and, here I must ask of you a favour, enlighten me about your thoughts and ideas.