 An early and very well known argument derives from the work of B. Libet (1985, 2004). Libet asked participants in his experiments to make an unplanned movement when they felt the urge to do so, and to report (using a specially designed clock-like instrument) the time when they felt the urge to move. Recordings of participants’ brain waves were made during these experiments, and Libet found a signal (the “readiness potential”, RP) that correlated with the movements. The key finding was that (after allowing for corrections due to neural transmission times) the RP occurred about 350 ms earlier than the time that participants reported having the urge to move. Libet himself allowed for the possibility of a veto after the urge that would block the movement. However, many have drawn an implication that the conscious urge to make a movement comes too late to causally contribute to a movement that has already been initiated by brain processes (that were detected by the RP measurement). A corollary of this implication is that, to the extent we have an intuition that our urge to move caused the movement, we are subject to a causal illusion. The possibility of causal illusion, in turn, weakens the intuitive argument against epiphenomenalism explained in section 2.1 above.