 It is claimed that my reason for believing that others have minds similar to my own can be taken to be the same as the scientific realist’s reason for believing in the existence of electrons or other theoretical entities. On this way of thinking, mental states are taken to be inner states of an individual that provide the best explanation of the behavior we observe in others; any other explanation would be implausible. Pargetter (1984) considers the following as implausible alternative hypotheses: (i) God is working others like puppets; (ii) I am unique in having mental states as the cause of behavior; and (iii) that others have mental states but they are of an entirely different nature to my own.