Generally the doctrine that the mind (or sometimes the brain) works on representations of the things and features of things that we perceive or think about. In the philosophy of perception the view is especially associated with Malebranche and Locke, who, holding that the mind is the container for ideas, held that ‘of our real ideas, some are adequate, and some are inadequate. ‘Those I call adequate, which perfectly represent those archetypes which the mind supposes them taken from; which it intends them to stand for, and to which it refers them’ (Locke, Essay, ii. 31). The problems in this account were mercilessly exposed by Arnauld and Foucher, writing against Malebranche, and by Berkeley writing against Locke. The fundamental problem is that the mind is ‘supposing’ its ideas to represent something else, but it has no access to this something else except by forming another idea. It would be like comparing a portrait with a sitter, but without being given any access to the sitter except via the portrait. The difficulty is to understand how the mind ever escapes from the world of representations, or, in other words, how representations manage to acquire genuine content, pointing beyond themselves. In more recent philosophy, the analogy between the mind and a computer has suggested that the mind or brain manipulates symbols, thought of as like the instructions in a machine program, and that those symbols are representations of aspects of the world. The Berkeleyan difficulty then recurs. The programmed computer behaves the same way without knowing whether the sign ‘$’ refers to a unit of currency or anything else. The elements of a machine program are identified purely syntactically, so the actual operations of the system go on without any reference to any interpretation of them (see syntax). Hence, according to critics, there is no way, on this model, for seeing the mind as concerned with the representational properties of the symbols. The point is sometimes put by saying that the mind, on this theory, becomes a syntactic engine rather than a semantic engine. by Pragmatists also deny that representation is a central concept in understanding the mind and emphasize instead the activities surrounding a use of language, rather than what they see as a mysterious link between mind and world. See also form of life.