The assignment here was to conjecture as to the state of my consciouness after a presupposed exchange of all my molecules with those of the professor.

First, I had to form a judgement as to whether swapping parts from two type-identical cars (owned by different people) until all parts have been exchanged means that ownership has also been swapped.

Next, was a decision whether, if the professor began to get all my molecules, what would happen to me. What if, still further, they organized themselves the same way?

Lastly, the question was as posed: what happens to my Self if my professor gets all my component molecules?

It seems logical, as regards the exchange of car parts, that once it was complete, we would have traded cars. The car that was originally mine would now be yours and vice versa. In the final accounting, though, this is more or less ir-relavent since we began with "type-identical" cars. The most drastic change that might have occurred would be if our cars were different colours. Mine may have been tuned up more recently, or longer ago, but we'd still have just swapped. No more, no less.

The second question doesn't speak directly of trading, but rather of you gaining my molecules in some unspecified fashion. This being the case, it is impossible to say whether I would necessarily have to get your body. This seems a possibility, but an extremely unlikely one. You may well be losing your molecules getting mine, so yours are going somewhere, but the odds are infinitesimally small that the place they happen to go is to me. Not "Impossible" – just "Vastly Unlikely."

If, on the other hand, the molecules you receive from me are organized exactly the same way as mine, then yes, you will have my body: My body is unique – there may well have been many very similar to it in the past, and will likely be many more just as similar in the future, but none has been or will be exactly the same. If you're walking around in a body made of molecules that came from it and organized themselves exactly the same way, then you'll have my body. In a very significant way, you'll have become me: genetically. If all the molecules you get from me are indeed organized exactly as mine are now, you'll have my DNA, a combination of the genetic alphabet has never before existed and will not come around again prior to the heat death of the Universe (unless Nietzsche is right, in which case you're going to be doing this a lot!). You'd best hope I haven't committed any crimes (or, at a minimum, that I didn't leave any loose hairs lying about the scene).

This leads nicely into your last question: while you may become me from a genetic standpoint, there is some intangible way in which the question of memory and identity fails to lend itself to such definitive answers. Is my memory encoded physically on the surface of my brain? If so, then it looks like you get to know all my embarrassing secrets whether I want to tell you or not. Or is my memory, my consciousness, some kind of field effect caused by the motion of electricity through the manifold coil-like folds of the brain that experiences them? In that case, you may well keep your memories and mine will be left to the whims of chance.

I am disposed to believe that biological science will one day soon answer that question, but it has not done so yet. However, if memory were entirely encoded physically, then we should theoretically, be able to revive long-dead John Locke and have him remember who he is. Our experience says we cannot, though: Even people dead a few minutes experience memory loss when revived. It isn't always total, but some amnesia is common. This suggests that somehow or other, the continuity of that electrochemical flow through the physical brain is essential to the maintenance memory.

Two other considerations come to mind. One is the matter of the amount of time that elapses during this process and the other is whether you are aware of it while it's happening.

If the exchange of your molecules for mine is instantaneous, that is, if it happens so fast that at one instant you are entirely you and the next you are, physically at least, entirely me, then I suspect a very odd thing will happen: you will be who you conceive yourself to be, but in my body. Meanwhile, unless I get very, very lucky, my identity will in that instant be annihilated. I say this because the field would not be interrupted. You will experience some dizziness, though: my neural pathways will be utterly unfamiliar to you – it's going to take you some time and some physical therapy to use my muscles, just as it would if you lost part of your brain in a car accident. But the field would have been unbroken. Your consciousness as you understand it would simply be riding on a different bus.

I am going out on a limb by saying that, one biology may chop out from under me, but I subscribe to the field effect theory, not the physical encoding one. To give it it's due, I will say that, should my memory be physically resident in my brain, then you're the one who's out of luck. Neither of us will be aware anything's happened but in my case it will be because nothing has in fact happened. You won't know because you'll have ceased to exist in this scenario (again, unless the unlikely happens and all your molecules pop up again in the same form in the place of mine). You cannot become me: if my consciousness persists then I still exist – especially my consciousness still inheres in a body that has my DNA. It is the sheer absurdity of this scenario, in part, that leads me to believe that consciousness and memory are largely a result of a field effect.

But what if it occurs at less than instantaneous speed? What if, to take the latter case, you suddenly notice that your body is being replaced with mine, and "my" memories inexplicably start showing up in "your" brain? If their memories, can you notice that you don't remember them? Or will they seamlessly integrate into you consciousness allowing me to enfold, envelop and consume you? I should think that you'd be unaware that you were leaving, that you'd accept the memories in "your" brain as yours and be convinced they'd always been there. What other point of view could you take of what would seem to be the memories in your own head? After the process was done, the results would be the same as if it had happened instantaneously. I'd be there and you wouldn't be. It's certainly distasteful.

But my belief in field effect consciousness is, I hope, rooted in better soil than personal disgust. I think you would notice you were being usurped – and I'd notice I was coming apart. As your molecules were replaced with mine, regardless of where yours go, you would perceive it happening. You won't get my memories or my identity because, just as would be the case in the instantaneous example, your consciousness would not be interrupted. You'd be perturbed, no doubt, especially as you gradually lost motor function because of my ingrained neural pathways, but you, not I, would be the one experiencing the whole thing. I'll be over here watching myself disintegrate, probably unaware that I am also losing my mind, until there isn't enough brain left to sustain my awareness and I wink out as a conscious being. You'll just be flailing around wondering what's going on. But inside, it will still be you as you understand you.

I say this because, even though you will now be liable should I have left fingerprints somewhere incriminating, it is our nature to give far greater weight to our consciously held conceptions of ourselves than to the physical form in which that consciousness inheres when we conceive of who we are: identity, for us as conscious beings, is consciousness itself, not form; mind, not body. Once you get used to my body's way of doing things, you will merely have to get used to an unfamiliar face looking back in the mirror.

The cars in the first example, is easily dispensed with because they are purely physical entities – they have no self-conception, no consciousness, no thingness that can be disassociated with the parts that make them up. If we swap parts until each and every one have returned to their original configurations, we have in fact swapped cars. The same thing applies to our bodies. They are physical entities; if we trade molecules, the trade is a purely physical one. But the molecules in my body are a vehicle for, not the seat of, my self-awareness. If you get them, so be it, one of two things will happen. Either you will still be you, now residing in the physical shell I have become accustomed to and I won't exist anymore or you will be annihilated and I won't know anything has happened until this class is canceled – forever.