(1) In any case, his argument that it may not be possible to have provable Friendliness and it makes more sense to take an incremental approach to AGI than to not do AGI until Friendliness is proven seems reasonable.
That it's impossible to find a course of action that is knowably good, is not an argument for the goodness of pursuing a course of action that isn't known to be good.
Certainly, but it is an argument for
(2) the goodness of pursuing a course of action that is known to have a chance of being good.
You point out a correct statement (2) for which the incorrect argument (1) apparently argues. This doesn't argue for correctness of the argument (1).
(A course of action that is known to have a chance of being good is already known to be good, in proportion to that chance (unless it's also known to have a sufficient chance of being sufficiently bad). For AI to be Friendly doesn't require absolute certainty in its goodness, but beware the fallacy of gray.)
[...] SIAI's Scary Idea goes way beyond the mere statement that there are risks as well as benefits associated with advanced AGI, and that AGI is a potential existential risk.
[...] Although an intense interest in rationalism is one of the hallmarks of the SIAI community, still I have not yet seen a clear logical argument for the Scary Idea laid out anywhere. (If I'm wrong, please send me the link, and I'll revise this post accordingly. Be aware that I've already at least skimmed everything Eliezer Yudkowsky has written on related topics.)
So if one wants a clear argument for the Scary Idea, one basically has to construct it oneself.
[...] If you put the above points all together, you come up with a heuristic argument for the Scary Idea. Roughly, the argument goes something like: If someone builds an advanced AGI without a provably Friendly architecture, probably it will have a hard takeoff, and then probably this will lead to a superhuman AGI system with an architecture drawn from the vast majority of mind-architectures that are not sufficiently harmonious with the complex, fragile human value system to make humans happy and keep humans around.
The line of argument makes sense, if you accept the premises.
But, I don't.
Ben Goertzel: The Singularity Institute's Scary Idea (and Why I Don't Buy It), October 29 2010. Thanks to XiXiDu for the pointer.