  H.P. Grice (1961) originally propounded the main argument for the CTP. (Other advocates of the theory include Pears (1976) and Strawson (1974)). Grice’s argument takes the following general form. We are asked to consider cases in which a subject is having an experience appropriate for seeing an object of a certain kind—e.g., the subject is having an experience such that it seems to her as if there is a clock in front of her. There is in fact a clock in front of the subject, however, the subject fails to see the clock, for the subject’s experience is a hallucination—perhaps induced by a neuroscientist stimulating her visual cortex. It is argued that such cases are indeed conceivable, and that in such cases the best explanation of the subject’s failure to see the object before her is the absence of an appropriate causal connection between the object and her experience. Hence the CTP is justified.