I believe the sentience is an emergent property of biological intelligence. I assume it is related to the instinct for self-preservation. It is easy to preserve yourself if you see a clear distinction between you and the rest of the environment, or you and the other members of your species. An insect such as a grasshopper cannot distinguish between other grasshoppers, or between other grasshoppers and a plastic model of a grasshopper at the end of a stick held by a biologist. I doubt such a limited intelligence can have any sense of self, or any sense of destiny or future.
If computers can become sentient, surely only large, fast ones with lots of memory will be capable of it. A desktop computer probably has fewer effective connections than a grasshopper brain. A grasshopper brain has ~1 million neurons, but lots of dendrites and they all work in parallel, giving it more processing power than a computer with 4 billion transistors. So I doubt anything like today's desktop computer could be sentient, or even intelligent at a level much higher than a grasshopper. A much larger MPP computer or supercomputer such as Watson might have enough capacity to be sentient. I wouldn't know. There will soon be computers far larger than Watson, and I expect they will have enough capacity. The question is: will they have a natural propensity toward sentience, or is that something that has to be deliberately programmed? In other words, is it emergent? I can well imagine a computer a million times faster, bigger and with more base knowledge and simulated common sense than Watson which is not sentient, and which has absolutely no emotion, will, or opinion. The Google system is approaching that state. The programmers at Google are hard at work trying to make it into something like that, because that would be profitable. Not as an academic experiment in artificial intelligence. I do not see why a totally non-sentient supercomputer would be impossible. Even if sentience is emergent, I expect it would not be hard to prevent it by not including some set of capabilities. The Internet as a whole has more connections than a human brain, and far larger memory, but there is no evidence it is tending toward any kind of intelligence above the level of an insect. - Jed
