Walton, Douglas

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University of WindsorScholarship at UWindsorOSSA Conference Archive OSSA 3May 15th, 9:00 AM - May 17th, 5:00 PMCommentary on ReedDouglas WaltonFollow this and additional works at: http://scholar.uwindsor.ca/ossaarchivePart of the Philosophy CommonsThis Commentary is brought to you for free and open access by the Faculty of Arts, Humanities and Social Sciences at Scholarship at UWindsor. It hasbeen accepted for inclusion in OSSA Conference Archive by an authorized conference organizer of Scholarship at UWindsor. For more information,please contact scholarship@uwindsor.ca.Walton, Douglas, "Commentary on Reed" (1999). OSSA Conference Archive. 104.http://scholar.uwindsor.ca/ossaarchive/OSSA3/papersandcommentaries/104Author:  Douglas Walton  In Response To: Chris Reed's Building monologue (c)2000 Douglas WaltonThe problem of premise availability facing the designer of a monologueargument is vitally important for many applications of natural languagegeneration by computers, as Reed has shown. And I certainly agree with hisanalysis in assigning central importance to argument diagrams of the kindstudied by Freeman (1998), and argumentation schemes of the kind studiedby Hastings (1963) and Kienpointner (1992). But I must admit I have notthought too deeply about this problem myself, and wondered how the problemcould be solved in a specific case, or set of cases, representing applicationsof the theory.One very important kind of application would be the case of a student orresearcher writing an argumentative essay. This would be a monologue case,because the student has to pick a topic or question, and then think out how hecould best present the data he has found so far to prove or support somedesignated thesis. As such then, the type of dialogue would be what I havecalled persuasion dialogue. The student's task is to find some interestingthesis and then give the strongest possible reasons supporting the truth of thatthesis. But of course dialogue is also implicitly involved, as I would say italways is in such cases, because the student must also formulate the strongestpossible objections to his arguments , and then try to counter these objectionsas persuasively as possible. This is basically the task of a written essay orpaper, of the kind we are all so familiar with.The student has a dual problem to confront. One problem is to find aninteresting thesis and argue for that. But the other is to collect as much relevantinformation as possible, from reliable sources that can be documentedadequately. This part could be called the research component, or collecting ofdata. It is always a problem with writing any kind of essay of this sort that youhave to divide your time between these two tasks. At some point, you have nomore time to collect data, and you have to start writing. But then after havingwritten a rough draft, you may have to go back to the research task, and lookup some information that has now turned out to be vital to your line of argument.The problem of premise availability is surely a cycling back and forth betweenthese two tasks. First, you have a thesis to prove, T. To support T, you need tofind a network of linked and convergent arguments based on premises that canbe supported by the given evidence. The process for this task is surelyabductive in nature. The student has to reason backwards, or look for bestexplanations, among the set of propositions that he has already assembled ashis data set. But in some instances, this process will pick out propositions notin the data base. Then the student will have to do more research, and try to findsources that support these propositions or not.Normally in persuasion dialogue, the task is to find premises that yourrespondent will accept, or as we say, is committed to. But that is the problemwhen you are dealing with an individual. If you are doing a history essay, thenyour professor will tend to accept whatever the main experts in the field arealso generally inclined to accept. So your problem is not just one of convincingthis individual professor, but of writing a history essay of a sort that would beconvincing to professional historians. Let's consider a specific example.Suppose you have decided as your thesis a counterfactual proposition : ifcertain individuals in German politics has resisted Hitler more strongly, insteadof acting on their own personal interests, Hitler would never have gotten intopower. To argue for this thesis, you have to carry out two tasks. First, you haveto collect a lot of documented facts about what happened in German politics in1933, just before Hitler came to power. Then you have to use these supposedfacts as premises to support you thesis. As part of the second task, you haveto reply to certain objections to your arguments. For example, someone mightobject that popular support for Hitler was so strong, he would have gotten intopower anyway. You might reply that popular support for the Nazis was indecline at this time, and that if Hitler could have been held back just a littlewhile longer, he never would have gotten into power. But once this issue hasbeen raised, and both sides looked at, you may be well advised to do somefurther research. You may have to dig up some more facts on the extent ofpopular support for the Nazis, just before and during the time of Hitler'sappointment as chancellor of Germany. Such facts would be election statisticsand any poll outcomes that were known.Thus I would say that the problem of premise availability involves two relatedsubtasks of argument construction in monologue. One is the abductivesearching for premises, and links between them and your thesis, among yourexisting knowledge base. The other is the task of adding, at strategic points, toyour existing knowledge base. These could be called the abductive task andthe information-seeking task, respectively. Of these two, the information-seeking task is less analytically exciting. You find gaps in your argumentation,and the task is simply one of collecting the relevant information, if you can, thatwould seal up the gaps. The abductive task is more exciting. How do youconstruct a "logic of discovery" to search out the best evidence needed tosupport your given thesis? Can such a task be automated? It looks like it can,and it appears that the current research in knowledge based systems isalready quite familiar with this type of task. It is the famous technique of"reasoning backwards" or abduction. As Reed shows, it partly uses deductiveand inductive reasoning, of the kinds familiar for so long in logic. But it alsorequires the new argumentation schemes - forms of reasoning that arecontextual and nonmontonic - and are neither deductive nor inductive in nature.They represent forms of intelligent guesswork of the kind Peirce calledabductive. They give a small probative weight for or against a conclusion thatis not itself conclusive, but that only has some place in a much larger body oftotal evidence in a case. What defines "total evidence" is a relative matter, andcan be subject to change as new information comes into a case. What is vitalin any given case is the argument diagram. You not only have small argumentdiagrams at the local level, in relation to any localized claim, argument, orcounter-argument. You also have two global argument diagrams in any givencase. One represents the total evidence for the given thesis. The otherrepresents the total evidence against that thesis, or for the opposite thesis.What is the best computational method for carrying out the abductive task I donot know. What I do know is that any good method, or even a bad method, ofthis kind would be extremely valuable as a piece of educational technology. Itwould be valuable not only for its uses in educational software, but also for thetheoretical light it would throw on methods of informal logic. A method of thiskind would throw a lot of light, for example, on the problem of handling linkedand convergent arguments in argument diagrams, and the problem ofenthymemes. In fact, I think that the best solutions to these problems will onlybe forthcoming by a joining of forces between computer scientists and thosenow working in the field of argumentation studies. So I close my commentaryby commending Reed's research and his use of work in argumentation studiesand informal logic. I would like to see much more of this kind of cooperativeresearch, and hope to encourage it as best I can.ReferencesJames B. Freeman, Dialectics and the Macrostructure of Arguments, Berlin,Foris, 1998.Arthur C. Hastings, A Reformulation of the Modes of Reasoning inArgumentation, Evanston, Illinois, Ph.D. Dissertation, 1963.Manfred Kienpointner, Alltagslogik : Struktur und Funktion vonArgumentationsmustern, Stuttgart, Fromman-Holzboog, 1992. 

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