Gary Gutting contends that it's not a question of facts but of intentions and meanings:
The fact that I raised my arm can be established by scientific observation—even by the impersonal mechanism of a camera. But whether I meant to wave in greeting or to threaten an attack is a matter of interpretation that goes beyond what we can scientifically observe. Similarly, scientific observations can show that a brain event caused a choice. But whether the choice was free requires knowing the meaning of freedom. If we know that a free choice must be unpredictable, or uncaused, or caused but not compelled, then an experiment can tell us whether a given choice is free. But an experiment cannot of itself tell us that a choice is free, anymore than a photograph by itself can record a threat.
The Dish 