AI Magazine Volume 16 Number 4 (1995) (© AAAI) Workshop Report but it has taken some time to put the The Workshop on full measure of their ideas together and make explicit pronouncements. Computational Dialectics There were two notable forerunners of AI workshops that explicitly con- templated argument. The last was run R. P. Loui successfully by Sergio Alvarado, who was able to interest a much larger number of researchers in natural lan- guage processing in the 1991 AAAI Spring Symposium Series. In contrast, the workshop in Seattle had a clear bias toward AI and law and knowl- ■ The 1994 Workshop on Computational attend. Gilad Zlotkin (Hebrew Univer- edge representation. The population Dialectics was held during the 1994 sity), Sandra Carberry (University of National Conference on AI. At issue shift is natural: In the intervening Delaware), Gerhard Brewka (Universi- years, formal models of argument were the following ideas: (1) dialectic ty of Vienna, Austria), Jon Doyle (Mas- have grown precise. They are much has something to do with computation, sachusetts Institute of Technology), (2) AI has something new to contribute more precise than at any time in the Anne Gardner, L. Thorne McCarty to the understanding of dialectic, and few thousand years that Western (Rutgers University), and Kevin Ashley (3) dialectic approaches to long-stand- intellectuals have studied argument as (Pitt) also contributed their intellectu- ing AI problems permit new progress. a logicolinguistic phenomenon. The al weight to the proceedings. This article outlines the significant AI and law community has felt the research presented at the conference. At issue were the following ideas: impact of the developments and has (1) dialectic has something to do decided for some time to take the lead with computation, (2) AI has some- toward further developments. The om Gordon (GMD) had the idea thing new to contribute to the organizers of the last Nonmonotonic for an American Association for understanding of dialectic, and (3) Reasoning Workshop (Brewka) and Artificial Intelligence (AAAI) dialectic approaches to long-standing T the next Knowledge Representation workshop on computational dialec- AI problems permit new progress. and Reasoning Conference (Doyle) tics, and the intriguing phrase is his. Dialectic is at the core of models of were present, and their presence is It is to his credit that the idea has rational inquiry that are honest evidence that AI and law will be fol- earned a further hearing in a German about procedural rationality. It is no workshop that he is currently organiz- accident that Herbert Simon and lowed, if not joined, in its pursuits. ing with colleagues on the continent. Dialectic has had a tough time For the workshop in Seattle, Washing- being respectable in this century. In ton, at AAAI-94, our committee its more logically sober guises, it is included Johanna Moore (Pitt) and Dialectic … is basically basically the idea that rational inquiry Katia Sycara (Carnegie Mellon Univer- is best achieved through largely adver- sity). It is to their credit that they the idea that rational sarial discourse. Dialectic is an old agreed to be on the committee, per- inquiry is best achieved idea that simply will not disappear. It ceiving the fundamental nature of the is the idea of structured linguistic workshop’s topic and the broadness of through largely interactions proceeding according to a its implications in time. adversarial discourse. protocol. The term computational Senior colleagues Hajime Yoshino dialectics was meant to describe an (Meijigakuin University) and Layman area of activity in AI that considers Allen (University of Michigan) were the language and protocol of systems that mediate the flow of messages able to attend: Both have records of Nicholas Rescher, collaborating in interdisciplinary leadership, where between agents constructing judg- the early 1960s, would shortly there- law and formal systems meet, and ment, agreement, or other social after discover the idea of procedural their input is always valued. Trevor choice to recognize or achieve an out- rationality (Simon) and a compact Bench-Capon from England (Imperial come in a fair and effective way. logical description of dialectic College), Daniel Poulin from Quebec Significant papers were presented (Université de Montréal), and perhaps (Rescher). Why should there be by Brewka and McCarty: Brewka gave half of the other attendees made the debate instead of just unpacking the a formal reconstruction of Rescher’s trip to Seattle just for the workshop, declared logical entailments of non- formal theory of disputation within although other scheduled speakers, monotonic or defeasible reasons? the framework of default reasoning. If notably Jaap Hage from The Nether- The answer has to be that there is Rescher is indeed the high mark in lands (University of Limburg) and search, and the answer makes no the history of understanding dialec- Arthur Merin from Germany (Univer- sense unless search is limited. Simon tic, which now seems incontrovert- sity of Stuttgart), were unable to and Rescher both knew this answer, ible, then Brewka represents the first Copyright © 1995, American Association for Artificial Intelligence. All rights reserved. 0738-4602-1995 / $2.00 WINTER 1995 101 Workshop Report direct step forward in nearly two ble concept probably evolved into his classes. Graphic support is provided decades. Of course, these two decades famous idea of an open-textured term for diagramming arguments interac- were active years for the nonmono- to be defined perhaps using defeasi- tively. Like much of the work pre- tonic reasoning community that ble rules (which can be traced to the sented at the 1991 symposium, it makes Brewka’s work possible. Brewka philosopher Ludwig Wittgenstein by extends the idea of Toulmin diagrams uses the precision of his revised way of philosopher Friedrich Wais- for arguments into the world of default framework to answer ques- mann). However, McCarty took the graphic user interfaces. It is ambitious tions that Rescher did not or could opportunity to assail AI’s work on work in part because all the research not answer. I disagreed with Doyle defeasible reasoning. He said that that builds on the GIBIS (Conklin) and over the long-term importance of pre- defeasible rules were trivial devices AQUANET (Marshall et al.) experiences cisely answering exactly these ques- that could be eliminated in favor of points to the average user’s unwill- tions; I felt that variations of the two kinds of negation. As devices for ingness to frame arguments formally. model remain to be explored at a rule-based programming, they pro- In addition, it insists that the argu- higher level of abstraction rather than vide no advance over intuitionistic ments to be diagrammed be scientific to obsess over one variation’s details. logic programming (says McCarty). arguments. Surely, scientific argu- Still, a full literature search of cita- They are trivial, that is, when com- ments have their own special logic. tions of Rescher’s 1977 monograph, pared to the defeasibility of open-tex- Cavalli-Sforza has for a while been Dialectics, reveals no useful formal tured concepts, the logic of which interested in Toulmin’s own attempts extension or clarification of the logi- remains unanalyzed (says McCarty, to apply his work on argument to cal system prior to Brewka. The downplaying the work of case-based specialized forms of reasoning, such Argentine constructive logician Gino reasoning researchers, especially his as legal, decision-theoretic, or scien- Roetti is the only person who has colleagues Edwina Rissland, Ashley, tific. BELVEDERE is significant because it told me he read the book in 1977, and David Skalak). Ironically, the AI made good of Toulmin, with possible saying he knew then that is was an and law luminary, McCarty, like the ramifications in the interactions of important little book but that it was deontic legal logician Carlos Alchour- users with scientific databases; it is perhaps ahead of its time. Was an ron, chooses to attack a legal inven- perhaps more significant in this understanding of it really impossible tion (defeasible reasoning) on techni- respect than it is successful as a tool until AI had had its nonmonotonic cal aesthetics. for teaching young scientists. reasoning excursions? The issue of open texture was Freeman gave a synopsis of her dis- McCarty’s paper was as electrifying made more pointed by a paper pre- sertation work, which also included a as it was an object of impassioned sented by Pierre St-Vincent. He and graphic system for diagramming disagreement. Although primarily Poulin gave a nondialectic, nondefea- arguments based on Toulmin. Her historical and not essentially con- sible treatment of open-textured con- system provides an automated rea- cerned with the logic of dialectic, it cepts. These Canadians wanted to soner for additional support of the was recognized at once for its impor- analyze open texture as a normed or user. Although her representational tance. McCarty noted that it was the fuzzy concept, in the manner that scheme seeks to mix dialectic ideas greatest Anglo-American philosopher might be appropriate at a meeting with measures of plausibility, the of law, H. L. A. Hart, who introduced about uncertainty in AI. A role for audience found nothing objection- the logicolinguistic world to the term dialectic remained in St-Vincent’s able in her work. This reaction shows defeasible (Hart imported it from approach: Dialectic provided for an me that the