It isn't a definitive argument, but you could point out that various intelligent historical figures had different morals from modern intelligent people. Napoleon, for instance--his intelligence is apparent, but his morality is ambiguous. Newton, or Archimedes, or George Washington, or any of several others, would work similarly.
A problem with this argument is that it's using that slippery word, "intelligence"; one could argue that Jesus was the most intelligent person ever because he exerted the most optimization pressure, and his values (or our modern conceptions of them) just so happen to line up really well with the professed values of modern intelligent people. Same with Rousseau. Also, Archimedes barely knew any calculus—clearly he wasn't very intelligent.
I would like the argument to work, because at least it's relatively empirical, but it seems too easy to poke holes in.
One of the most annoying arguments when discussing AI is the perennial "But if the AI is so smart, why won't it figure out the right thing to do anyway?" It's often the ultimate curiosity stopper.
Nick Bostrom has defined the "Orthogonality thesis" as the principle that motivation and intelligence are essentially unrelated: superintelligences can have nearly any type of motivation (at least, nearly any utility function-bases motivation). We're trying to get some rigorous papers out so that when that question comes up, we can point people to standard, and published, arguments. Nick has had a paper accepted that points out the orthogonality thesis is compatible with a lot of philosophical positions that would seem to contradict it.
I'm hoping to complement this with a paper laying out the positive arguments in favour of the thesis. So I'm asking you for your strongest arguments for (or against) the orthogonality thesis. Think of trying to convince a conservative philosopher who's caught a bad case of moral realism - what would you say to them?
Many thanks! Karma and acknowledgements will shower on the best suggestions, and many puppies will be happy.