Which approach gives a higher expected value? Formal specification is compatible with Eliezer's ideas for friendly AI as something that will provably avoid disaster. It has some non-epsilon possibility of actually working. But its failure modes are many, and can be literally unimaginably bad. When it fails, it fails catastrophically, like a monotonic logic system with one false belief. "Tell the AI in English" can fail, but the worst case is closer to a "With Folded Hands" scenario than to paperclips.

I don't think that's how the analysis goes. Eliezer says that AI must be very carefully and specifically made friendly or it will be disasterous, but that disaster is not a part of being only nearly careful or specifically made enough : he believes an AGI told merely to maximize human pleasure is very dangerous (and probably even more dangerous) than an AGI with a merely 80% Friendly-Complete specification.

Mr. Loosemore seems to hold the opposite opinion, that an AGI will not take instructions to unlikely results, unless it was exceptionally unintelligent and thus not very powerful. I don't believe his position says that a near-Friendly-Complete specification is very risky -- after all, a "smart" AGI would know what you really meant -- but that such a specification would be superfluous.

Whether Mr. Loosemore is correct isn't cause by whether we believe he is correct, just as whether Mr. Eliezer is not wrong just because we choose a different theory. The risks have to be measured in terms of their likelihood from available facts.

The problem is that I don't see much evidence that Mr. Loosemore is correct. I can quite easily conceive of a superhuman intelligence that was built with the specification of "human pleasure = brain dopamine levels", not least of all because there are people who'd want to be wireheads and there's a massive amount of physiological research showing human pleasure to be caused by dopamine levels. I can quite easily conceive of a superhuman intelligence that knows humans prefer more complicated enjoyment, and even do complex modeling of how it would have to manipulate people away from those more complicated enjoyments, and still have that superhuman intelligence not care.