Stevan Harnad (2001) Ttt Guarantees Only Grounding: but Meaning = Grounding + Feeling. Psycoloquy: 12(045) Symbolism Connectionism (12)

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Psycoloquy 12(045): Ttt Guarantees Only Grounding: but Meaning = Grounding + Feeling

Reply to Fetzer on Harnad on Symbolism-Connectionism

Stevan Harnad
Department of Electronics and Computer Science
University of Southampton
Highfield, Southampton
SO17 1BJ
United Kingdom


Robotic grounding is not behaviorism, it is the reverse engineering of our cognitive capacities. It guarantees grounding (i.e., the autonomous capacity to connect symbols to the external objects they are about with no mediation by an external interpreter) but not meaning, which calls for something more (but not the resources Fetzer (2001) proposes). It calls for whatever it is that gives us feelings. But here too, the Total Turing Test is the final arbiter (yet no guarantor).

    REPRINT OF: Harnad, S. (1993). Harnad's response to Fetzer. Think 2:
    12-78 (Special Issue on "Connectionism versus Symbolism" D.M.W.
    Powers & P.A. Flach, eds.).

1. Fetzer (2001) thinks TTT grounding is based on an isomorphism between internal symbols and features of the world. It is not. You could have isomorphism with the world (under an interpretation) in an ungrounded symbol system. The TTT requires full causal interaction with the real world of objects and their features, and the capacity for this must be equal to and indistinguishable from our own. This is not an "experiential" test but an empirical one: The robotic capacities (to discriminate, categorize, identify, manipulate, describe, and discourse about objects) must really be there, and really exercised, and really not discriminably different from those of a real human being (Harnad 2001a).

2. This is not behaviorism, it is reverse engineering (Harnad 1994): Fetzer asks for a theory; the theory will be the full description of the internal structures and processes that succeeded in making the robot pass the TTT. I don't know what Fetzer's 'motives, beliefs, ethics, etc.' are, but once we know exactly what internal (robotic) states actually deliver the TTT goods, we may be able to fill in the blanks with those. What does not look as if it will do is an internal something that is 'aware' of signs or symbols, for then the job begins with finding out what internal structures and processes that homuncular module consists of. The only internal causes and effects I can imagine adding to this engineering assignment would amount to moving toward the TTTT (which I would only be helpful insofar as it gave us hints to accelerate our progress toward passing the TTT, the final arbiter).

3. On the other hand, all this reverse engineering will yield only grounding, not necessarily meaning: Meaning is grounding plus feeling (Harnad, 1992), and no one has any sort of functional explanation of feeling (Harnad 2001b)!


Fetzer, J. H. (2001) The TTT is not the final word. PSYCOLOQUY 12(044)

Harnad, S. (1992, unpublished) There Is Only One Mind/Body Problem. (Presented at Symposium on the Perception of Intentionality, XXV World Congress of Psychology, Brussels, Belgium, July 1992) International Journal of Psychology 27: 521 (Abstract)

Harnad, Stevan (1994) Levels of Functional Equivalence in Reverse Bioengineering: The Darwinian Turing Test for Artificial Life. Artificial Life 1(3):293-301.

Harnad, S. (2001) Grounding symbols in the analog world with neural nets -- A hybrid model. PSYCOLOQUY 12(034)

Harnad, S. (2001a) Minds, Machines, and Turing: The Indistinguishability of Indistinguishables. Journal of Logic, Language, and Information 9(4): 425-445. (special issue on "Alan Turing and Artificial Intelligence")

Harnad, Stevan (2001b) No Easy Way Out. The Sciences 41(2):36-42.

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