Perhaps everyone on the island is being "Clockwork Oranged". That is, through drugs, technology, and hypnosis, everyone believes they are on this island, when, in fact, they are somewhere else, like a facility. Perhaps the "flashback scenes" are, in one way or another, directly experienced by the characters while they are 'on the island', even if no one but Desmond experiences them on a consious level. These memories we have been seeing are either distorted visions of the persons past, or completely false- planted, as it were. Perhaps the test subjects have been run through the "island senario" many times, and this is what accounts for his (Desmonds) apparently precognative abilities; he simply remembers what happened the last time around.The characters that die on the island are, in fact, not really dead; they have just been pulled from the senario until the next time around.I believe Patchy knows that he cannot die; for whatever reason, he is never "pulled from the senario", regardless of what happens. This isn't to say that he knows why he cannot die; he could be completely ignorant of whats really going on. All he might know is that he does not die, regardless of what happens. I think he believes in the reality of what appears to be going on around him.I think they all believe in the reality of the island, including Ben. He believes he was inducted into the program as a child. If this theory is correct, I don't think anyone on the island knows whats going on, except perhaps Jacob. My prediction for the last episode of the series is everyone who ever played a character on the show "waking up" together, somewhere, to discover all are alive and well, and they finally get to go home.
The motives behind such a progeram could be benevolent (the subjects volunteered to participate), or they could be malevolent (forced indoctrination/kidnapping). It's impossible to say who does what, and why they do it, at this point in the story.

TPTB said this was not the case, but thanks for reminding me to watch the clockwork orange. :)