have “strategies,” which have minimal
structure, and motivations, which are
encapsulated in a simple real-valued
utility function. (This in fact carries
even less information than is suggested
by the use of numbers, as the theory is
unchanged by any positive affine transformation of the numbers.) In real life,
and in computer programs attempting
to behave intelligently, we find use for a
much broader vocabulary. For example,
agents are able to take certain actions
and not others; have desires, goals, and
intentions (the belief-desire-intention
combination giving rise to the pun
“beady-eye agent architecture”); and
make plans. Apparently these abstract
notions are useful both in effecting
intelligent behavior and in reasoning
about it. Philosophers have written
about them (for example, Bratman1)
and there have been attempts—albeit
preliminary ones—to formalize these
intuitions (starting with Cohen and
Levesque3). Some in AI have advocated
embracing an even broader vocabulary
of emotions (such as the recent provocative albeit informal book by Minsky. 23)
Is game theory missing out by not considering these concepts?
it may already lead to a certain extent
beyond the obvious and the familiar.
Here theory and application corroborate each other mutually. Beyond this
lies the field of real success: genuine
predictions by theory. It is well known
that all mathematized sciences have
gone through these successive phases
of evolution. 40
So at least von Neumann, the father
of modern-day game theory and computer science, attached importance to
spanning the spectrum from the theoretical to the applied. Pragmatics may
be critical to achieving von Neumann
and Morgenstern’s third stage, and it
could propel a joint endeavor between
computer science and game theory.
I thank Alon Altman, Joe Halpern, Sam Ieong, Daphne
Koller, Tim Roughgarden, Moshe Vardi, Mike Wellman, and
anonymous referees for their useful help and suggestions.
Of course, all errors, opinions, and erroneous opinions are
Science operates at many levels. For
some, it is sufficient that scientific theories be clever, beautiful, and inspirational. Others require that any science
eventually make contact with compelling
applications and be subjected to empirical evaluation. Without personally weighing in on this emotional debate, I note
that in his 2004 presidential address at
the Second World Congress of the Game
Theory Society, 17 Kalai reprised the three
stages of any science as discussed by von
Neumann and Morgenstern:
[W]hat is important is the gradual
development of a theory, based on a
careful analysis of the ordinary everyday
interpretation of economic facts. The
theory finally developed must be mathematically rigorous and conceptually
general. Its first applications are necessarily to elementary problems where the
result has never been in doubt and no
theory is actually required. At this early
stage the application serves to corroborate the theory. The next stage develops
when the theory is applied to somewhat
more complicated situations in which
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This work has been supported by NSF grant TR–0205633.
Yoav Shoham ( http://cs.stanford.edu/~shoham) is a
professor of computer science at Stanford University,