An old view, stretching back at least to William of Ockham’s Summa Logicae, holds that thinking occurs in a language of thought (sometimes called Mentalese). Fodor revives this view. He postulates a system of mental representations, including both primitive representations and complex representations formed from primitive representations. For example, the primitive Mentalese words JOHN, MARY, and LOVES can combine to form the Mentalese sentence JOHN LOVES MARY. Mentalese is compositional: the meaning of a complex Mentalese expression is a function of the meanings of its parts and the way those parts are combined. Propositional attitudes are relations to Mentalese symbols. Fodor calls this view the representational theory of mind (RTM). Combining RTM with CCTM, he argues that mental activity involves Turing-style computation over the language of thought. Mental computation stores Mentalese symbols in memory locations, manipulating those symbols in accord with mechanical rules.