Instituut voor Taal- en Kennistechnologie
Institute for Language Technology and Artificial Intelligence
Harnad responds
Boyle's is a friendly commentary, so there is no point dwelling on the
minor differences there are between us: A system that can pass the TTT
is good enough for me. As a matter of logic, transduction will have to
be part of its successful functioning. How much of its transducer
activity will remain analog, how much will be discretized and
filtered, how much will be processed syntactically (by
``pattern-matching'') -- these are all empirical questions about how
that future system will actually succeed in passing the TTT. I happen
to have my own hypotheses (neural nets filtering out learned
invariants in the analog projection, connecting them to arbitrary
symbolic names, which are then manipulated compositionally, but
inheriting the nonarbitrary constraint of the grounding) and Boyle may
have his. The point, however, is that just as there are no a priori
degrees of passing the TTT (that's what the ``Total'' ensures), there
are no a priori degrees of grounding (at least not in the sense I use
the word). Ungrounded symbols mean what they mean only because (within
their formal system) they can be systematically interpreted as meaning
what they mean. In contrast, the meanings of grounded symbol systems
are grounded in the system's capacity for robotic interactions with
what the symbols are about.
Neither immunity to Searle's Chinese Room Argument nor
TTT-groundedness can guarantee that there's somebody home in such a
robot, but I happen to think they're the best we can ever hope to do,
methodologically speaking. If Boyle's ``structure preserving
superposition'' can do a better job, all power to it. But at this
point, it seems to amount to what Searle would call ``speculative
neurophysiology,'' whereas transduction and TTT-power have face
validity.
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