Well, does someone who can't control their thoughts really control their own behavior? Is there any basis for thought/behavior that science knows of, that is not physiological? Scientists have never put out a press release saying "we've discovered that there are non-physiological processes called 'will' that actually make you even more in control than previously suspected". It's always the other way around - they find that things we used to assign to "will", are in fact caused by something else.