And Guy, putting aside your religious refusal to accept the internal logic of the show regarding artificial intelligence. The lightbulb's programming was not capable of taking any action that would directly result in a loss of life. The Hippocratic Oath was hard coded into him, and he can't kill any more than Internet Explorer can render large DOMs.
This is what I was trying to say earlier. Like it or not, the Doctor was the chief medical officer on Voyager. Regardless of whether his decision was influenced by pre-programmed ethical subroutines or an actual conscience, there was no way he was going to kill someone against their will. And like teya
said, just about ANY doctor, organic or not, would have come to the same decision.
However, I don't think there's any more point in arguing the case for the Doctor's sentience than there is in arguing over whether or not killing Tuvix was the right decision. It's obvious that everyone has their own opinions, and it's highly unlikely that any of us are going to change our minds. Clearly, none of us are on the fence about it.