 RTT concerns propositional attitudes and the mental processes in which they figure, such as deductive inference, reasoning, decision-making, and planning. It does not address perception, motor control, imagination, dreaming, pattern recognition, linguistic processing, or any other mental activity distinct from high-level cognition. Hence the emphasis upon a language of thought: a system of mental representations that underlie thinking, as opposed to perceiving, imagining, etc. Nevertheless, talk about a mental language generalizes naturally from high-level cognition to other mental phenomena.