I may seem old fashioned in this (probably am) but I still don't believe that machines will ever become "sentient" in the way that you and I, our cats, dogs, whales, and butterflies, and even our bacteria are. The reason lies in the impenetrable barrier between teleogenic and teleonomic systems. Teleogenic systems are those that self-engender their own intentions, in pursuit, ultimately, of only one agenda: to eat, survive, and reproduce, so that their offspring can do likewise. And teleogenic systems exist in a holarchy, consisting of both tightly coupled systems (like cells and organisms) and loosely coupled systems (like communities and ecosystems and Gaia herself. ). Conversely, teleonomic systems (e.g. everything from a simple thermostat to the most complex supercomputer systems on the planet) are designed from outside of themselves, and whatever purposes they might have are programmed into them by their human designers. And none of them, essentially, give a shit whether they live or die. For example, no "smart bomb" has ever been smart enough to refuse to hit its target and blow itself up!