title: Unified Theories of Cognition
text: # Unified Theories of Cognition
  
  Unified Theories of Cognition is a 1990 book by Allen Newell. Newell argues for the need of a set of general assumptions for cognitive models that account for all of cognition: a unified theory of cognition, or cognitive architecture. The research started by Newell on unified theories of cognition represents a crucial element of divergence with respect to the vision of his long-term collaborator, and AI pioneer, Herbert Simon for what concerns the future of artificial intelligence research. Antonio Lieto recently drew attention to such a discrepancy, by pointing out that Herbert Simon decided to focus on the construction of single simulative programs (or microtheories/"middle-range" theories) that were considered a sufficient mean to enable the generalisation of “unifying” theories of cognition (i.e. according to Simon the "unification" was assumed to be derivable from a body of qualitative generalizations coming from the study of individual simulative programs). Newell, on the other hand, didn’t consider the construction of single simulative microtheories a sufficient mean to enable the generalisation of “unifying” theories of cognition and, in fact, started the enterprise of studying and developing integrated and multi-tasking intelligence via cognitive architectures that would have led to the development of the Soar.
  
  ## Contents
  
  Newell argues that the mind functions as a single system. He also claims the established cognitive models are vastly underdetermined by experimental data. By cognition, Newell means:
  
  * Problem solving, decision making, routine action
  * Memory, learning, skill
  * Perception, motor behavior
  * Language
  * Motivation, emotion
  * Imagining, dreaming, daydreaming
  
  After arguing in favor of the development of unified theories of cognition, Newell puts forward a list of constraints to any unified theory, in that a theory should explain how a mind does the following:
  
  * Behave flexibly as a function of the environment
  * Exhibit adaptive (rational, goal-oriented) behavior
  * Operate in real time
  * Operate in a rich, complex, detailed environment (Perceive an immense amount of changing detail; use vast amounts of knowledge; and control a motor system of many degrees of freedom)
  * Use symbols and abstractions
  * Use language, both natural and artificial
  * Learn from the environment and from experience
  * Acquire capabilities through development
  * Operate autonomously, but within a social community
  * Be self-aware and have a sense of self
  * Be realizable as a neural system
  * Be construable by an embryological growth process
  * Arise through evolution
  
  Newell's secondary task is to put forward the cognitive architecture Soar as an implementation of a UTC that meets the constraints above. Other efforts at unified theories of cognition cited in the book include ACT-R and the human processor model.
  
  