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From: harnad@mind.UUCP (Stevan Harnad)
Newsgroups: net.ai,net.cog-eng
Subject: Re: Searle, Turing, Symbols, Categories
Message-ID: <3@mind.UUCP>
Date: Sat, 18-Oct-86 11:16:14 EDT
Article-I.D.: mind.3
Posted: Sat Oct 18 11:16:14 1986
Date-Received: Tue, 21-Oct-86 05:41:55 EDT
References: <158@mind.UUCP> <150@cwrudg.UUCP> <160@mind.UUCP> <1882@mmintl.UUCP>
Organization: Cognitive Science, Princeton University
Lines: 93
Keywords: Robotics, Symbol-Crunching, Category Representation, Analog Representation, Induction
Xref: watmath net.ai:3790 net.cog-eng:781
Summary: The Object/Symbol Conversion Problem: A Rebuttal to the Argument that Transduction, A/D, D/A and Effectors are Trivial in Mind-Modeling


In response to some of the arguments in favor of the robotic over the
symbolic version of the turing test in (the summaries of) my articles
"Minds, Machines and Searle" and "Category Induction and Representation"
franka@mmintl.UUCP (Frank Adams) replies:

>	[R]elating purely symbolic functions to external events is
>	essentially a solved problem. Digital audio recording, for
>	example, works quite well. Robotic operations generally fail,
>	when they do, not because of any problems with the digital
>	control of an analog process, but because the purely symbolic
>	portion of the process is inadequate. In other words, there is
>	every reason to expect that a computer program able to pass the
>	[linguistic version of the] Turing test could be extended to one
>	able to pass the robotic version...requiring additional development
>	effort which is tiny by comparison (though likely still measured
>	in man-years).

This argument has become quite familiar to me from delivering the oral
version of the papers under discussion. It is the "Triviality of
Transduction [A/D conversion, D/A conversion, Effectors] Argument" (TT
for short).

Among my replies to TT the central one is the principled
Antimodularity Argument: There are reasons to believe that the neat
partitioning of function into autonomous symbolic and nonsymbolic modules
may break down in the special case of mind modeling. These reasons
include my "Groundedness" Argument: that unless cognitive symbols are
grounded (psychophysically, bottom-up) in nonsymbolic processes they remain
meaningless. (This amounts to saying that we must be intrinsically
"dedicated" devices and that our A/D and our "decryption/encryptions"
are nontrivial; in passing, this is also a reply to Searle's worries
about "intrinsic" versus "derived" intentionality. It may also be the
real reason why "the purely symbolic portion of the process is inadequate"!)
This problem of grounding symbolic processes in nonsymbolic ones in the
special case of cognition is also the motivation for the material on category
representation.

Apart from nonmodularity and groundedness, other reasons include:

(1) Searle's argument itself, and the fact that only the transduction
argument can block it; that's some prima facie ground for believing
that the TT may be false in the special case of mind-modeling.

(2) The triviality of ordinary (nonbiological) transduction and its
capabilities, comparared to what organisms with senses (and minds) can
do. (Compare the I/O capacities of "audio" devices with those of
"auditory" ones; the nonmodular road to the capacity to pass the total
turing test suggests that we are talking here about qualitative
differences, not quantitative ones.)

(3) Induction (both ontogenetic and phylogentetic) and inductive capacity
play an intrinsic and nontrivial role in bio-transduction that they do
not play in ordinary engineering peripherals, or the kinds of I/O
problems these have been designed for.

(4) Related to the Simulation/Implementation Argument: There are always
more real-world contingencies than can be anticipated in a symbolic
description or simulation. That's why category representations are
approximate and the turing test is open-ended.

For all these reasons, I believe that Object/Symbol conversion in
cognition is a considerably more profound problem than ordinary A/D;
orders of magnitude more profound, in fact, and hence that TT is
false.

>	[E]ven in a purely formal environment, there turn out to be a
>	lot of real things to talk about. Primitive concepts of time
>	(before and after) are understandable. One can talk about nouns
>	and verbs, sentences and conversations, self and other. I don't
>	see any fundamental difference between the ability to deal with
>	symbols as real objects, and the ability to deal with other kinds
>	of real objects.

I don't completely understand the assumptions being made here. (What
is a "purely formal environment"? Does anyone you know live in one?)
Filling in with some educated guesses here, I would say that again the
Object/Symbol conversion problem in the special case of organisms'
mental capacities is being vastly underestimated. Object-manipulation
(including discrimination, categorization, identification and
description) is not a mere special case of symbol-manipulation or
vice-versa. One must be grounded in the other in a principled way, and
the principles are not yet known.

On another interpretation, perhaps you are talking about "deixis" --
the necessity, even in the linguistic (symbolic) version of the turing
test, to be able to refer to real objects in the here-and-now. I agree that
this is a deep problem, and conjecture that its solution in the
symbolic version will have to draw on anterior nonsymbolic (i.e.,
robotic) capacities.

Stevan Harnad
princeton!mind!harnad