 Work by Wegner and Wheatley (1999), Wegner (2002), and Linser and Goschke (2007), describes participants who have judged themselves to have partial control of movements over which they in fact lacked control. But if we can demonstrably have illusions about being in control, our sense of being in control of our actions cannot be taken as evidence that our conscious intentions actually have effects in our (nonlinguistic) behavior. Such illusions further imply that we sometimes lack knowledge of the actual course of causation of our actions.