I notice that I am confused. Manipulation may have occurred if someone's free will has been overridden. There was a nice post about the compatibility between free will and determinism, which I agree with, but I find the issue of manipulation shows I still have a fuzzy idea about what free will means.

The work on Friendly AI gives me a fairly good idea about how it's possible to avoid being manipulative to a person, but the answer - following their extrapolated volition - is much too high a standard. What if you want to be neutral rather than selflessly and altrusticly benevolent towards them?

Still, their extrapolated volition seems to be relevant.