Well, I don't think anyone can argue that if we create an AI smarter in nearly every way than any given human, several or a large amount of those AIs could create an even smarter AI, and so forth recursively. The only question is if we indeed will, and if so when (even 100-150 years isn't that far off if you think about it). Given the huge impact it would have on society (for better or worse), it's perfectly reasonable to be a matter of public debate.