Types and Properties of Dialogue

1. Types and Properties of Dialogue Lecture of Douglas Walton at University of Lugano, December 19, 2007

2. Argument in Dialogue An argument is a social and verbal means of trying to resolve, or at least contend with, a conflict or difference that has arisen between two parties engaged in a dialogue (Walton 1990, p. 411). According to this definition, an argument necessarily involves a claim that is advanced by one of the parties, typically an opinion that the one party has put forward as true, and that the other party questions, or is opposed to.

3. Reasoning, Argument and Explanation Reasoning can be used for differing purposes, for example in explanations and arguments. Reasoning is a process of inference in passing from certain propositions known or assumed to be true to other propositions in a sequence(Walton, 1990). Abductive reasoning is inference to the best explanation (Walton, 2004). Practical reasoning seeks out a prudential line of conduct for an agent in a particular situation, while theoretical reasoning seeks evidence that counts for or against the truth of a proposition (Walton, 1990).

4. Abductive Reasoning • I see some tracks on the trail, and they look like bear tracks. • This is a national park, where one might expect there are some bears. • The best explanation is that a bear passed this way recently. • Conclusion: a bear passed this way recently.

5. Practical Reasoning • Goal Premise: my goal is to give a lecture on dialogue theory in Lugano on April 17. • Means Premise: the means for giving the lecture is to make up some Power Point Slides by April 11. • Conclusion: I should make up some Power Point slides by April 11. • Practical reasoning seeks out a prudential line of conduct for an agent in a particular situation.

6. Theoretical Reasoning • Premise: Everyone who lives in Lugano lives near Lago Maggiore. • Premise: Mario lives in Lugano. • Conclusion: Mario lives near Lago Maggiore. • This example is a deductively valid argument assuming ‘everyone’ is universal.

7. What is an Explanation? The new dialectical theory (Walton, 2005, chapter 6) models an explanation as a dialogue between two agents in which one agent is presumed by the other to understand something, and the other agent asks a question meant to enable him to come to understand it as well. The model articulates the view of Scriven (2002, p. 49): “Explanation is literally and logically the process of filling in gaps in understanding, and to do this we must start out with some understanding of something.”

8. Reasoning, Argument and Explanation Reasoning can be used for differing purposes, for example in explanations and arguments. Reasoning is a process of inference in passing from certain propositions known or assumed to be true to other propositions in a sequence. Abductive reasoning combines explanation with argument. Here we mention again the distinction between theoretical reasoning and practical reasoning. Theoretical reasoning provides evidence that a conclusion is true or false. Practical reasoning concludes that action should be taken.

9. How to Tell the Difference Test to judge whether a given text of discourse contains an argument or an explanation. Take the statement that is the thing to be proved or explained, and ask yourself the following question. Is it taken as an accepted fact, or something that is in doubt? If the former, it’s an explanation. If the latter, it’s an argument. The Goal of Dialogue is Different The purpose of an argument is to get the hearer to come to accept something that is doubtful or unsettled. The purpose of an explanation is to get him to understand something that he already accepts as a fact.

10. Speech Act • SPEECH ACT: "in saying something, we do something", as when a minister joins two people in marriage saying, "I now pronounce you husband and wife." • Examples • Greeting (in saying, "Hi John!", for instance), apologizing ("Sorry for that!"), asserting something ("It is snowing"), asking a question ("Is it snowing?"), making a request ("Could you pass the salt.”) or making a promise ("I promise I'll give it back") are typical examples of speech acts. In saying, "Watch out, the ground is slippery", Peter performs the speech act of warning Mary to be careful. • In saying, "I will try my best to be at home for dinner", Peter performs the speech act of promising to be at home in time. [Wikipedia]

11. Speech Act Moves in a Dialogue

12. Example of a Hamblin Dialogue

13. Dialogue Typology

14. Properties of Six Basic Types of Dialogue

15. Four Systems of Persuasion Dialogue Four minimal systems of dialogue were constructed in (Walton, 1984) as structures to model the kinds of argumentation used in connection with fallacies. They start from a minimal one called CB, and proceed to successively stronger versions. You can find this book as a pdf file on my web page. http://io.uwinnipeg.ca/~walton/books/LDG84bk.pdf

16. The Dialogue System CB • CB is a simple system of persuasion dialogue in which two parties, White and Black each have a thesis to be proved. • Each tries to prove his/her thesis using only arguments that have commitments of the other side as premises. • A commitment is a statement that a party has gone on record as accepting by putting forward a statement, like, “Lugano is north of Milan”.

17. Locution Rules of CB • Statements: Statement letters, S, T, U, ..., are permissible locutions, and truth-functional compounds of statement-letters. • Withdrawals: ‘No commitment S’ is the locution or withdrawal (retraction) of a statement. • Questions: The question ‘S?’ asks ‘Is it the case that S is true?’ • Challenges: The challenge ‘Why S?’ requests some statement that can serve as a basis in (a possibly defeasible) proof for S.

18. Commitment Rules of CB • After a player makes a statement, S, it is included in his commitment-store. • After the withdrawal of S, the statement S is deleted from the speaker's commitment store. • ‘Why S?’ places S in the hearer's commitment-store unless it is already there or unless the hearer immediately retracts his commitment to S. • Every statement that is shown by the speaker to be an immediate consequence of statements that are commitments of the hearer then becomes a commitment of the hearer's and is included in his commitment store. • No commitment may be withdrawn by the hearer that is shown by the speaker to be an immediate consequence of statements that are previous commitments of the hearer.

19. Dialogue Rules of CB • Each speaker takes his turn to move by advancing once locution at each turn. A no-commitment locution, however, may accompany a why-locution as one turn. • A question ‘S?’ must be followed by (i) a statement ‘S’, (ii) a statement ‘Not-S’, or (iii) ‘No commitment S’). • ‘Why S?’ must be followed by (i) ‘No commitment S’ or (ii) some statement ‘T’, where S is a consequence of T.

20. Deliberation Dialogue • A group of concerned citizens is getting together to decide whether to support a proposal for a new sewer system in their municipality. They have a town hall meeting. • Arguments are presented on both sides. • Example: the new system would be too costly.

21. Five Stage Model of Deliberation Dialogue Stage 1: Opening the dialogue. Stage 2: Sharing information. Stage 3: Making proposals and counter-proposals. Stage 4: Confirming accepted proposals. Stage 5: Closing the dialogue. (McBurney, Hitchcock and Parsons, 2007)

22. Information-Seeking Dialogue • Current problem with contradictions in scientific finding on nutrition and health: “too much information” (Newsweek, March 13 cover story, p. 46). • Information-seeking requires not only transmission of “facts” (ask-tell), but also critical analysis of reliability of “facts”.

23. Classification of Subtypes

24. Four Meanings of ‘Examination’

25. Interrogation Dialogue

26. Examining an Expert Opinion

27. A Small Profile of Dialogue

28. Examples of Dialectical Shifts • A contractor and homeowner are negotiating on the price of a foundation repair, and they shift to the issue of whether it would be a good idea to install and additional inch of concrete wall. • During a divorce dispute, the couple are negotiating on who should looks after the children, but the mediator shifts the discussion to a persuasion dialogue on the issue of which party is in the best position to undertake the task of looking after the children. Each side must give reasons, and this shift makes the dialogue less eristic.

29. Embedding of Persuasion into Negotiation Dialogue (Walton and Godden, 2005)

30. References Charles L. Hamblin, Fallacies, London, Methuen, 1970. Charles L. Hamblin, Mathematical Models of Dialogue, Theoria, 7, 1971, 130-155. James D. Mackenzie, ‘Question Begging in Non-Cumulative Systems’, Journal of Philosophical Logic, 8, 1979, 117-133. Peter McBurney, David Hitchcock and Simon Parsons, ‘The Eightfold Way of Deliberation Dialogue’, International Journal of Intelligent Systems, 22, 2007, 95-132. Chris Reed and Douglas Walton, Towards a Formal and Implemented Model of Argumentation Schemes in Agent Communication, Autonomous Agents and Multi-Agent Systems, 11, 2005, 173-188. Douglas Walton, Logical Dialogue-Games and Fallacies, Lanham, University Press of America, 1984. Available under ‘Books’ on the web page of Douglas Walton: http://io.uwinnipeg.ca/~walton/ Douglas Walton and David M. Godden, ‘Persuasion Dialogue in Online Dispute Resolution’, Artificial Intelligence and Law, 13, 2005, 273-295.