It’s the year 2045, and Dr. Evil and the Singularity Institute have been in a long and grueling race to be the first to achieve machine intelligence, thereby controlling the course of the Singularity and the fate of the universe. Unfortunately for Dr. Evil, SIAI is ahead in the game. Its Friendly AI is undergoing final testing, and Coherent Extrapolated Volition is scheduled to begin in a week. Dr. Evil learns of this news, but there’s not much he can do, or so it seems. He has succeeded in developing brain scanning and emulation technology, but the emulation speed is still way too slow to be competitive.
There is no way to catch up with SIAI's superior technology in time, but Dr. Evil suddenly realizes that maybe he doesn’t have to. CEV is supposed to give equal weighting to all of humanity, and surely uploads count as human. If he had enough storage space, he could simply upload himself, and then make a trillion copies of the upload. The rest of humanity would end up with less than 1% weight in CEV. Not perfect, but he could live with that. Unfortunately he only has enough storage for a few hundred uploads. What to do…
Ah ha, compression! A trillion identical copies of an object would compress down to be only a little bit larger than one copy. But would CEV count compressed identical copies to be separate individuals? Maybe, maybe not. To be sure, Dr. Evil gives each copy a unique experience before adding it to the giant compressed archive. Since they still share almost all of the same information, a trillion copies, after compression, just manages to fit inside the available space.
Now Dr. Evil sits back and relaxes. Come next week, the Singularity Institute and rest of humanity are in for a rather rude surprise!
Thinking about this a bit more, and assuming CEV operates on the humans that exist at the time of its application: Why would CEV operate on humans that do exist, and not on humans that could exist? It seems this is what Dr. Evil is taking advantage of, by densely populating identity-space around him and crowding out the rest of humanity. But this could occur for many other reasons: Certain cultures encouraging high birth rates, certain technologies or memes being popular at the time of CEV-activation that affect the wiring of the human brain, or certain historical turns that shape the direction of mankind. A more imaginative scenario: what if another scientist, who knows nothing about FAI and CEV, finds it useful to address a problem by copying himself into trillions of branches, each examining a certain hypothesis, and all the branches are (merged/discarded) when the answer is found. Let's further say that CEV t-zero occurs when the scientist is deep in a problem-solving cycle. Would the FAI take each branch as a separate human/vote? This scenario involves no intent to defraud the system. It also is not manipulation of a proxy, as there is a real definitional problem here whose answer is not easily apparent to a human. Applying CEV to all potential humans that could have existed in identity-space would deal with this, but pushes CEV further and further into uncomputable territory.
Because for every possible human mind, there's one with the sign flipped on it's utility function. Unless your definition of "human" describes their utility function, in which case ...