16.1815, Review: Philosophy of Language: Shieber (2004)

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LINGUIST List: Vol-16-1815. Thu Jun 09 2005. ISSN: 1068 - 4875.

Subject: 16.1815, Review: Philosophy of Language: Shieber (2004)

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1)
Date: 09-Jun-2005
From: Larry Smith < lsmith at ncbi.nlm.nih.gov >
Subject: The Turing Test

	
-------------------------Message 1 ----------------------------------
Date: Thu, 09 Jun 2005 02:07:46
From: Larry Smith < lsmith at ncbi.nlm.nih.gov >
Subject: The Turing Test


EDITOR: Stuart Shieber
TITLE: The Turing Test
SUBTITLE: Verbal Behavior as the Hallmark of Intelligence
SERIES: Bradford Books
PUBLISHER: MIT Press
YEAR: 2004
Announced at http://linguistlist.org/issues/16/16-524.html


Larry H. Smith, U.S. National Center for Biotechnology Information,
Bethesda, MD.

OVERVIEW

This book is an anthology of twenty famous papers on the Turing test
related to the question of whether machines can be said to think. Each
chapter of the book was previously published, except for the final chapter
which is an essay by Noam Chomsky appearing in print for the first time.
Gathering these papers into a single book aims to dispel some
misconceptions about the often referenced Test and its famous criticisms.

Summary of Chapters

The first three chapters contain precursory writings from Descartes,
demonstrating that animals cannot possess souls (which for Descartes means
the same thing as "capable of thought"), and a rebuttal from the 18th
century philosopher Julien Offray de la Mettrie, who vehemently argued the
opposite in "Man a Machine."

The next four chapters are papers by Turing, beginning with the 1950
essay "Computing Machinery and Intelligence" in which he first proposed
his test. There are many sensible re-interpretations of the Turing test,
but it should be remembered that Turing originally framed it as a
challenge put to a computer to imitate a human communicating by teletype.
The remaining papers further clarify Turing's thinking on the origin and
meaning of the test, and include the transcript of a 1952 BBC interview of
Turing and some of his eminent peers.

The remaining chapters can be grouped into opponents and proponents of the
Turing test. Pinsky offers a humorous parody of the test designed to
uncover human neurotic thinking. Gunderson rejects Turing's proposal
because it is based on logic that could also be used to imply that rocks
are capable of imitating human toe-stepping behavior. Purtill claims that
a machine that merely recalls stored responses cannot be called
intelligent, to which Sampson gives a rebuttal. Millar argues that the
concept of intelligence is necessarily and exclusively applicable to
humans only. French then argues that because human behavior is entirely
conditioned on human experience (or, what he calls subcognition), that it
is impossible for a non-human ever to pass a Turing test.

Then comes Searle's famous "Chinese room" article, in which it is argued
that an English speaking person following instructions for carrying on a
conversation in Chinese cannot possibly be judged intelligent on the basis
of those conversations. This is followed by a similar refutation by Block
using his "Aunt Bertha" machine, also called a "Blockhead", which is able
to imitate human behavior perfectly for a given time period by searching a
database of all sensible responses (typical say, of his Aunt Bertha)
stored for that time period.

Dennett rebuts Block by insisting that we must apply the
label "intelligent" when it appears to fit, and that we are not qualified
to judge a thing on the basis of its composition. Moor makes a similar
argument, that an unrestricted test is strong evidence supporting the
theory that a machine does indeed "think." Stalker then criticizes Moor
for his willingness to apply a human theory of mind when an engineering
theory of computers seems more appropriate. And Moor gets the last word by
pointing out that actually both theories are valid. Finally, in a
previously unpublished paper, Chomsky argues that it is idle to debate
whether a machine can exemplify such a non-transferable human concept
as "thinking", quoting Wittgenstein that "We only say of a human being and
what is like one that it thinks."

Summary of Essay

Shieber's comments begin in the introduction and continue throughout the
book as introductory material between chapters, filling approximately
sixty pages. He prepares the reader for each stage of dispute and suggests
terminology to help tie the papers together. The chapters are ordered by
relevance so that each chapter precedes its extensions and rebuttals, even
when they are not chronological. Shieber subtly encourages the reader to
accept Turing's defenders, to reject his critics, and to appreciate his
originality and insight.

CRITICAL EVALUATION

The papers in this anthology (except for Shieber's essay and Chomsky's
unpublished paper) are well known historical documents. Likewise,
Shieber's essay nobly avoids taking a stand for or against any of the
arguments, which are evaluated in subsequent papers anyway. I therefore
confine my remarks to the general ideas expressed in the book.

Warnings

Despite the subtitle, this book contains nothing that might be called
linguistics. The authors seem to agree implicitly that the ability to use
language is simply a convenience; any behavior that can exhibit
intelligence could substitute in the test (though, to be consistent with
Turing's insight, the behavior should be digitized). Also, although
Shieber starts the book by quoting humorous pop references to the Turing
test, there are no further references, and no analysis of the social
impact of the Turing test.

Personal experience

I began this book with excitement, which quickly faded when I came to the
responses following Turing. The opposing views made me feel like I was
reading a "blog" or some opinionated newsgroup. The light of reason only
returned with Dennett and the subsequent articles culminating with
Chomsky. It is the unprofitable duty of professional academics to respond
with carefully reasoned, rational, point by point rebuttals to misleading
pronouncements of their peers, and we should thank de La Mettrie, Sampson,
Dennett, Moor, and Chomsky for speaking up. Readers' experiences may
differ, but anyone who makes the effort to consider each paper carefully
and in the given sequence will develop or at least sharpen their opinion
of machine intelligence and the Turing test in particular.

Praise for Turing

Turing's intuitions are penetrating. He argues that we shouldn't even try
to assess whether machines think, but instead we should ask whether
machines are capable of intelligent behavior. This was not meant to
substitute for the original question; he meant to dump the original
question completely. He also realized that in assessing intelligent
behavior, people are likely to have human prejudices, which might be
overcome if the behavior is digital from the start. And finally, it was
obvious to Turing that computers would eventually be called "intelligent,"
and I suspect he believed this was a fact of human psychology and not
philosophy.

Criticism 1

There are two questions that are hopelessly confounded, (1) can machines
can think? and (2) does passing a Turing test prove that a machine thinks?
Shieber calls the second one the "big question." Proponents of Turing
understand that it is ridiculous to argue about whether a machine can
think, and consider observable behavior instead. While critics build their
arguments on tacit assumptions that machines cannot think. Not once do the
critics attempt to explicate the concept of "thinking" nor how it differs
from "intelligent behavior."

Criticism 2

A common strategy, from Descartes to SearlE, is to propose a
counterexample, a "wedge" as Schieber calls it, of an "unintelligent"
machine that appears to behave intelligently. The problem is that the
arguments given for why the proposed machine isn't intelligent, an
argument Shieber would call the "spark," when they are given, are not
convincing. The opponents seem to rely on sympathetic emotional prejudices
of the reader. To take one example, Gunderson quotes Turing, word for
word, but with the computer replaced by a device that drops a box of
rocks, and the goal to imitate a person stepping on someone's foot.
Gunderson apparently hopes the reader will have the gut reaction
that "rocks can't imitate people." But as later authors point out, the
behavior describes the system, not the rocks or other isolated components.
By providing terminology for it, Shieber calls attention to the defect,
but his analysis is too forgiving.

Criticism 3

In fact, there is a human capacity to recognize "thinking"
and "intelligent behavior", but it is explained by cognitive psychology
and not philosophy. It's unfortunate that none of the authors seemed to
take this seriously.

An alternative thesis

There is something to be said for the relative neutrality of Shieber's
essay, however the book might have been more stimulating if it had taken a
stronger position. For instance, the philosophical debate of the Turing
test was a historical mistake which had the unfortunate consequence of
leading many a good mind down a garden path. That might have been avoided
if Wittgenstein had been taken seriously, and if these philosophers had
accepted that there is an essential human psychology in the concepts
of "thinking" and "intelligence." Chomsky, a linguist, puts the endeavor
on the right foot, but then he advocates dumping the question altogether.
On the other hand, the introduction of the Turing test into pop culture
may have been harmless, and may even have been beneficial. But that is a
sociological question which is outside the scope of this anthology.

Final recommendation

The papers in this anthology should be well known to anyone who wishes to
express a "professional" opinion on the Turing test. I would also
recommend this book to students and lovers of philosophy, especially those
with an interest in AI. The selection and ordering of the chapters, as
well as the relative neutrality of the essay, are well designed to guide
the reader to their own opinion, even though the conclusion is subtly
biased.

ABOUT THE REVIEWER

Larry Smith has a PhD in math, and is a research consultant at the U.S.
National Center for Biotechnology Information where he works on
information retrieval and extraction techniques for the large public
collection of biomedical text maintained there. His interests include
statistical, syntactic, and semantic language modeling.





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