it has been taken as being more like Realism. His own words hint at something in the middle, as he suggests that the self is as real as a center of gravity, "an abstract object, a theorist's fiction", but operationally valid. As a way of thinking about things, Dennett's intentional stance is entirely consistent with everyday commonsense understanding; and, thus, it meets Eleanor Rosch's (1978, p. 28) criterion of the "maximum information with the least cognitive effort". Rosch argues that, implicit within any system of categorization, are the assumptions that: (a) the major purpose of any system of categorization is to reduce the randomness of the universe by providing "maximum information with the least cognitive effort", and (b) the real world is structured and systematic, rather than being arbitrary or unpredictable. Thus, if a particular way of categorizing information does, indeed, "provide maximum information with the least cognitive effort", it can only do so because the structure of that particular system of categories corresponds with the perceived structure of the real world. Also, the intentional stance meets the criteria Dennett specified (1995, pp. 50–51) for algorithms: (1) Substrate Neutrality: It is a "mechanism" that produces results regardless of the material used to perform the procedure ("the power of the procedure is due to its logical structure, not the causal powers of the materials used in the instantiation"). (2) Underlying Mindlessness: Each constituent step, and each transition between each step, is so utterly simple, that they can be performed by a "dutiful idiot". (3) Guaranteed Results: "Whatever it is that an algorithm does, it always does it, if it is executed without misstep. An algorithm is a foolproof recipe." Variants of Dennett's three stances The general notion of a three level system was widespread in the late 1970s/early 1980s; for example, when discussing the mental representation of information from a cognitive psychology perspective, Glass and his colleagues (1979, p. 24) distinguished three important aspects of representation: (a) the content ("what is being represented"); (b) the code ("the format of the representation"); and (c) the medium ("the physical realization of the code"). Other significant cognitive scientists who also advocated a three level system were Allen Newell, Zenon Pylyshyn, and David Marr. The parallels between the four representations (each of which implicitly assumed that computers and human minds displayed each of the three distinct levels) are detailed in the following table: Objections and