   Perceptions, beliefs, desires and intentions and many other “propositional attitudes” are mental states with intentionality. They are about or represent objects and states of affairs under a particular psychological mode or format.  Perceptions, beliefs, desires and intentions illustrate a basic duality of the intentionality of the mental: the duality between mind-to-world and world-to-mind directions of fit. In order to clarify this duality, Elizabeth Anscombe (1957, 56) considers a mere “shopping list”. The list may either be used as a set of instructions (or a blueprint) for action by a customer in a store or it can be used as an inventory by a detective whose purpose is to draw a record of what the customer is buying. In the former case, the list is not to be revised in the light of what lies in the customer’s grocery bag. But in the latter case, it is. If a mismatch should occur between the content of the grocery bag and the list used by the customer, then the blame should be put on the customer, not on the list. In the case of a mismatch between the content of the bag and the list drawn by the detective, the detective should correct his list.