Many people take drugs that are designed specifically to have some sort of affect on the brain: Ritalin, for example, or simply supplements such as ginsing to help memory and concentration. Anti-depressants are widely prescribed and used. These drugs alter the brain chemistry similar to the way exercising does. Yet surely taking ginsing every day does not mean I am no longer me, right?

Pacemakers are quite common these days - they are devices inserted into a person's body to monitor and act on a vital organ (in this case, the heart). Cochlear hearing implants are becoming common because they are better than external hearing aids for many people. Legs and hands are replaced by ever more real (that is, closely simulating the original) artificial versions for those involved in accidents. Hell, people have started receiving artificial hearts - a machine that functions for one of the very primary organs in the human body. But surely someone with a pacemaker, or even an artificial organ, is not less human or a different human than they were before? Implanting a hearing aid into my head does not mean I am no longer me, right?

How long before we start taking further steps in biotechnology? We may not be able to simulate a human brain any time soon, but we are not far from being able to create the inputs that feed information into a brain - all the little nerve connections that send the brain information from eyes, ears, touch, etc. We can already attach electrodes and stimulate certain parts of the brain. Surely we will get better at that as time passes and technology improves.

How long until we can move the brain of a human into a clone body with an empty skull, say, or something along those lines (maybe just putting a person's head onto a new body - perhaps an artificial one)? It may seem like science fiction now, but what we are doing today was science fiction not too long ago. Let us say we do move a brain into a new body, even an artificial one that is designed to perfectly simulate all the inputs and connections between the brain and the body - if I did this myself, would I no longer be me? The inputs would be the same as if I were in my old body, so does it not seem intuitively plausible to think that my brain would still work the same (assuming the logistics of this artificial body are taken care of, and it really does successfully do what it needs to)?

What if my brain were put into a chemical vat and a bunch of electrodes were attached to it, rather than putting it into a new body? If the electrodes could perfectly create the same input that a body would give, would there be any difference for the brain? If this was performed on me, would I be any less me?

What if someday we developed a computer more complex than the human brain - more connections, more space, able to do more tasks at a time and work in multiple-parallel, etc. Could such a computer not emulate a human's brain? And could it not be programmed to follow the same laws of neuron-firing that the brain uses? Couldn't inputs to the brain even be programmed as well - internal to the computer - rather than zapping a biological brain with electrodes? If this was all done flawlessly, if my brain was downloaded into this supercomputer, would I be any less me?

If we could download ourselves into a supercomputer, we could certainly download an identical copy into two different computers. It seems intuitively plausible that they would soon become two different 'I's as they began to have different experiences, and thus different thoughts, etc. Yet beginning as they do at the same point, are they not both a continuation of a single self? So are they the same 'I' - being the continuity of a single 'I' - or different, given their diverging experiences and thoughts after the downloading?

What if we tried and succeeded somehow at integrating a downloaded brain-emulation with other downloaded brain-emulations (from other people, say): would the self of each be destroyed creating a new entity, or would there be a continuity? Would each brain still think of itself as 'I' - the same 'I' as before - though perhaps with drastic changes other than a change in selfhood? When we interact with other humans in everyday life right now, we influence each other's brains, we pass on memes, we spark thoughts and communicate informational content - how hard is it to imagine doing this at a deeper level?

If not the above, what about the possibility of simply using electrodes (or whatever) to 'zap' your thoughts/experiences directly into someone else's head - to literally share your thoughts and communicate flawlessly? No more need for trying to work out definitions in some imperfect language that was never meant to be a formalized system. No more frustration at being unable to articulate your thoughts precisely. Just pure communication.

If you achieved this with another person - would you still remain the same 'I' afterwords (after the communication stopped, that is)? What if the communication never stopped, and you continued to share your thoughts and experiences (as a sort of super Vulcan mind-meld)? Would you think of yourself as the same 'I' as before?

What is the 'I'? How far can we stretch it before it becomes fundamentally different?