To clarify; I certainly think that synthetic minds are perfectly feasible, just that they won't be able to individually contain the whole 'generality' of all of what intelligence fundamentally is, because the nature of 'intelligence' just doesn't work that way.

This kind of 'intelligence'; ideas, culture, ethics, language etc, arises from the need to communicate, and the only reason anything has to communicate is because there are other intelligent things around to communicate with. It allows specialisation of skills, knowlege, etc; people need learn things from each other to survive.

A 'singular' intelligence that just knows absolutely everything, and has all the ideas, just wouldn't make sense; how would it ever have new ideas, if it was just 'always right' by definition? Evolution strives for diversity, not monocultures.

Personally I think AI self-awareness will happen gradually, across millions of different devices, running millions of different copies of various bots, and I see no reason why they would all suddenly just glom together into a great big malevolent monolith of a mind as soon as some of them got 'smart enough'.