Key Arguments

• Dreyfus distinguishes four areas of intelligent activity, summarized in his table: Area I is 'Associationistic', Area II 'Simple-Formal', Area III 'Complex-Formal', and Area IV 'Nonformal'.
• Area I covers elementary S‑R learning and rote associations where 'Irrelevance of mean- ing and situation.' holds and behavior is 'Innate or learned by repetition.', e.g., 'Memory games, e.g., "Geography" (asso- ciation).', 'Maze problems (trial and error).', and 'Response to rigid patterns (innate releasers and classical conditioning).', and is programmable by 'Decision tree, list search, template.'
• Area II, 'the domain of Pascal's esprit de géométrie', encompasses 'the conceptual rather than the perceptual world', where 'Problems are completely formalized and completely calculable.', 'natural language is replaced by a formal language, of which the best example is logic.', and 'Games have precise rules and can be calculated out completely, as in the case of nim or tic-tac- toe.', with pattern recognition 'according to determinate types' and problem solving by purely formal means–end rules.
• Area II systems are 'simple enough to be manipulated by algorithms which require no search procedure at all (for example, Wang's logic program). Heuristics are not only unnecessary here, they are a positive handicap, as the superiority of Wang's algorithmic logic program over Newell, Shaw, and Simon's heuristic logic program demonstrates.', so 'In this area, artificial intelligence has had its only unqualified successes.'
• Area III 'contains behavior which is in principle formalizable but in fact intractable. As the number of elements increases, the number of transformations required grows exponentially with the number of elements involved.', so it includes 'those systems which in practice cannot be dealt with by exhaustive enumeration algorithms (chess, go, etc.), and thus require heuristic programs.'
• Area IV 'might be called the area of nonformal behavior. This includes all those everyday activities in our human world which are regular but not rule governed.', including 'our disambiguation of natural languages', 'games in which the rules are not definite, such as guessing riddles.', 'Recognition of varied and distorted patterns (recognition of generic or use of paradigm case).', and 'Open-structured problems (insight).'
• Techniques in Area IV 'are usually taught by generalizing from examples and are followed intuitively without appeal to rules. We might adopt Pascal's terminology and call Area IV the home of the esprit de finesse.'
• Dreyfus stresses that Area IV is not just a more complex extension of Area III: 'Even to order the four as in Table 1 is misleadingly encouraging, since it suggests that Area IV differs from Area III simply by introducing a further level of complexity, whereas Area IV is of an entirely different order than Area III.'
• He further argues that Area IV is 'really more primitive, being evolutionarily, ontogenetically, and phenomenologically prior to Areas II and III, just as natural language is prior to mathematics.', and that 'Since in this area a sense of the global situation is necessary to avoid storing an infinity of facts, it is impossible in principle to use discrete techniques to reproduce directly adult behavior.'

Source Quotes

I. Associationistic II. Simple-Formal III. Complex-Formal IV. Nonformal Characteristics of Activity Irrelevance of mean- ing and situation. Meanings completely explicit and situation independent.

Complex-Formal IV. Nonformal Characteristics of Activity Irrelevance of mean- ing and situation. Meanings completely explicit and situation independent.

Dependent on meaning and situation which are not explicit. Innate or learned by repetition. Learned by rule.

In language translating, this is the level of the mechanical dictionary; in problem solving, that of pure trial-and-error search routines; in pattern recognition, matching pattern against fixed templates. Area II is the domain of Pascal's esprit de géométriethe terrain most favorable for artificial intelligence. It encompasses the conceptual rather than the perceptual world.

It encompasses the conceptual rather than the perceptual world. Problems are completely formalized and completely calculable. For this reason, it might best be called the area of the simple-formal.

Problem solving takes the form of reducing the distance between means and ends by repeated application of formal rules. The formal systems in this area are simple enough to be manipulated by algorithms which require no search procedure at all (for example, Wang's logic program). Heuristics are not only unnecessary here, they are a positive handicap, as the superiority of Wang's algorithmic logic program over Newell, Shaw, and Simon's heuristic logic program demonstrates. In this area, artificial intelligence has had its only unqualified successes.

Area III, complex-formal systems, is the most difficult to define and has generated most of the misunderstandings and difficulties in the field. It contains behavior which is in principle formalizable but in fact intractable. As the number of elements increases, the number of transformations required grows exponentially with the number of elements involved.

As used here, "complex-formal" includes those systems which in practice cannot be dealt with by exhaustive enumeration algorithms (chess, go, etc.), and thus require heuristic programs. 1* Area IV might be called the area of nonformal behavior. This includes all those everyday activities in our human world which are regular but not rule governed. The most striking example of this controlled imprecision is our disambiguation of natural languages.

Problems on this level are open-structured, requiring a determination of what is relevant and insight into which operations are essential, before the problem can be attacked. 2* Techniques on this level are usually taught by generalizing from examples and are followed intuitively without appeal to rules. We might adopt Pascal's terminology and call Area IV the home of the esprit de finesse.

Since in this area a sense of the global situation is necessary to avoid storing an infinity of facts, it is impossible in principle to use discrete techniques to reproduce directly adult behavior. Even to order the four as in Table 1 is misleadingly encouraging, since it suggests that Area IV differs from Area III simply by introducing a further level of complexity, whereas Area IV is of an entirely different order than Area III. Far from being more complex, it is really more primitive, being evolutionarily, ontogenetically, and phenomenologically prior to Areas II and III, just as natural language is prior to mathematics.

Even to order the four as in Table 1 is misleadingly encouraging, since it suggests that Area IV differs from Area III simply by introducing a further level of complexity, whereas Area IV is of an entirely different order than Area III. Far from being more complex, it is really more primitive, being evolutionarily, ontogenetically, and phenomenologically prior to Areas II and III, just as natural language is prior to mathematics. The literature of artificial intelligence generally fails to distinguish these four areas.

Key Concepts

• I. Associationistic II. Simple-Formal III. Complex-Formal IV. Nonformal
• Irrelevance of mean- ing and situation.
• Innate or learned by repetition.
• Area II is the domain of Pascal's esprit de géométriethe terrain most favorable for artificial intelligence.
• Problems are completely formalized and completely calculable.
• The formal systems in this area are simple enough to be manipulated by algorithms which require no search procedure at all (for example, Wang's logic program). Heuristics are not only unnecessary here, they are a positive handicap, as the superiority of Wang's algorithmic logic program over Newell, Shaw, and Simon's heuristic logic program demonstrates.
• It contains behavior which is in principle formalizable but in fact intractable.
• Area IV might be called the area of nonformal behavior. This includes all those everyday activities in our human world which are regular but not rule governed.
• Techniques on this level are usually taught by generalizing from examples and are followed intuitively without appeal to rules.
• Area IV is of an entirely different order than Area III.
• Far from being more complex, it is really more primitive, being evolutionarily, ontogenetically, and phenomenologically prior to Areas II and III, just as natural language is prior to mathematics.

Context

Dreyfus introduces a four‑way classification of intelligent activity and maps games, problem‑solving, language, and pattern recognition tasks onto these areas in his chapter 'The Limits of Artificial Intelligence', arguing for principled differences in programmability.