  The man in Locke's example seems to have the power to stay in the room, while lacking the power not to stay. Reid would probably deny that Locke's prisoner actually has the power to stay in the room, and there is some intuitive force to this view. The man, it seems, is in the hands of forces outside of his control. For Reid, what is in a person's power and what is ‘up to’ him or her are the same. Since it is not up to the man whether he stays (even if he thinks it is), it is not in his power to stay.