Historically, AI has been divided into two related but different approaches. "Strong" AI is interested in understanding and creating Minds; figuring out what intelligence is, how it works, how we do it, and how it could be done in general. "Weak" AI is interested in doing things that couldn't be done before; things that we do not have good algorithms for, or don't have any algorithms at all.
Those two are not opposed. Any advance on either side helps the other. In this argument, Norvig is representing an extreme version of weak AI since he seems to be arguing that it's possible that statistical methods are all there is. (I suspect that he isn't actually making that argument, though, but that strong AI's models are currently too simplistic to capture what statistical approaches can do.) Chomsky, on the other hand, seems to be caricaturing strong AI by saying that anything that doesn't directly shed light on the Grand Theory is worthless.
Those two are not opposed. Any advance on either side helps the other. In this argument, Norvig is representing an extreme version of weak AI since he seems to be arguing that it's possible that statistical methods are all there is. (I suspect that he isn't actually making that argument, though, but that strong AI's models are currently too simplistic to capture what statistical approaches can do.) Chomsky, on the other hand, seems to be caricaturing strong AI by saying that anything that doesn't directly shed light on the Grand Theory is worthless.