Neuroscience vs philosophy: Taking aim at free will : Nature News:
"The conscious decision to push the button was made about a second before the actual act, but the team discovered that a pattern of brain activity seemed to predict that decision by as many as seven seconds. Long before the subjects were even aware of making a choice, it seems, their brains had already decided. As humans, we like to think that our decisions are under our conscious control — that we have free will. Philosophers have debated that concept for centuries, and now Haynes and other experimental neuroscientists are raising a new challenge. They argue that consciousness of a decision may be a mere biochemical afterthought, with no influence whatsoever on a person's actions. According to this logic, they say, free will is an illusion. 'We feel we choose, but we don't,' says Patrick Haggard, a neuroscientist at University College London."

Why say a "mere biochemical afterthought"? All thoughts are biochemical.