  There is a puzzle that one encounters when trying to make sense of Reid's notion of power and which sheds some light on Reid's concept of moral liberty. The puzzle is this: Say that I have the power to do a cartwheel. According to Reid it follows that if I exert my power and thereby do a cartwheel, then I will be the efficient cause of my cartwheel. Imagine that I do this and imagine that every event is efficiently caused. Is my exertion of my power to do the cartwheel an event? If so, then it must have an efficient cause. Am I the efficient cause of the exertion? If not, then it doesn't seem that my cartwheel is a free action. After all, if I'm not the efficient cause of the exertion, then it wasn't up to me whether or not I tried to do the cartwheel, and it seems to follow that it wasn't up to me whether or not I did it. So, Reid seems forced to say that I am the efficient cause of the exertion to do the cartwheel. But then it follows from the definition of efficient causation that I exerted my power to exert myself to do the cartwheel. And, therefore, we can ask if I am the efficient cause of my exertion to exert myself to do the cartwheel. If not, then I didn't do the cartwheel freely; if so, then we will find ourselves having to ask about the efficient cause of the exertion to exert my power to exert. In short, Reid's views of power, efficient causation and moral liberty appear to be inconsistent with one another.