The Architecture of Higher Thought

1. The hierarchy of thought The idea that mental activity can be arranged according to a hierarchy of complexity has ancient origins, with roots in the Aristotelian psychological division of the soul into nutritive, perceptual, and intellectual faculties. Elementary functions dedicated to sustaining life undergird those that engage cognitively with the sensible world, which in turn support the active faculties of abstract reason. Higher faculties are meant to be those that have, in some sense, greater abstraction, generality, or complexity, which links them ethologically with distinctively human cognitive capacities, and developmentally with the mature state of the human cognitive system as opposed to that of the infant or child. 1 This distinction recurs at the inception of modern scientific psychology in Wundt, who sharply distinguished between sensory and perceptual capacities and other mental capacities such as learning and memory. For Wundt, the distinction between the two was not just between two types of cognitive process, but also implied a methodological dualism: sensory capacities were grounded in species-typical physiological mechanisms, while higher thought, insofar as it is conditioned by language and culture, must be studied using the methods of sociology and anthropology, as part of a distinctive Völkerpsychologie (Hatfield, 1997). This separation continued well into the 20 th century. Neisser (1967), for instance, does not share Wundt's methodological dualism, but his landmark textbook on cognitive psychology is divided into two major halves, one dealing with visual processing and the other with auditory processing, with higher cognitive processes (memory, language, and thought) confined to the brief epilogue. 1 For discussion of the Aristotelean divisions and related ancient notions, see Danziger (1997, pp. 21-35).