I recently saw an article about the idea that motivation is key to an effective AI. Not to be snarky, but this occured to me when I was in my teens, a couple decades ago. You can have all the heuristic abilities and fuzzy logic you can build, but until you can figure out how to program desire, your AI will probably be the worlds greatest navel starer.
The line of thought has always made me wonder about the nature of desire in humans. Disregarding intellectual and emotional goals for the moment, consider pain and pleasure. Purely chemical in nature, how do these things work the way they do? Chemically and biologically we can say what pain is all the way from receptors in the limbs to nerve signals up the spinal cord, but in the end why should the impulses they trigger in the brain be interpreted as unpleasant while others might be pleasant. The pragmatic answer is of course 'Because of millions of years of evolutionary pressure'. But, not having millions of years to dick about with neural nets, the question is then, how do we replicate the end result in a machine intelligence?