Transcript Panel Discussion on Ethical Rules and Particular Cases

The Current Agenda of
Argumentation Theory
Talk at New University of Lisbon, February 10, 2010,
11:00 am, Room 1.05, Building I&D.
Web page with pdf papers: http://dougwalton.ca
Douglas Walton: University of Windsor
Assumption Chair in Argumentation Studies
Distinguished Research Fellow of CRRAR
Centre for Research in Reasoning, Argumentation &
Rhetoric
CRRAR and Assumption
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CRRAR Mission Statement
The mission of the Centre for Research in Reasoning,
Argumentation and Rhetoric is to be a national and international
leader in individual and collaborative research into the theory and
practice of reasoning, argument and argumentation, and rhetoric from
the perspective of all related academic disciplines, and a leader in the
application and dissemination of this research.
CRRAR is also the home of the journal Informal Logic.
My position at CRRAR is that of Distinguished Research Fellow.
I also hold the Chair of Argumentation Studies at Assumption
University, a college in the University of Windsor.
Assumption was founded by the Basilian Fathers in 1870 as part of
Assumption University, which is now part of the University of Windsor.
What is an Argument?
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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 dialog by eliciting reasons on both sides (Walton,
2007).
According to this definition, an argument necessarily involves a claim
that is advanced by one of the parties, typically a claim that the one
party has put forward as true, and that the other party questions.
Arguments have premises and conclusions, they can be of different
kinds, they can be stronger or weaker (have weights), and different
standards of proof can be required of them in different contexts of use.
Deductive Argument
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Premise: Luigi is an Italian soccer player.
Premise: All Italian soccer players are divers.
Conclusion: Luigi is a diver.
It is logically impossible for the premises to be true and the conclusion
false.
But is the first premise true?
Inductive Argument
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Premise: Luigi is an Italian soccer player.
Premise: Most Italian soccer players are divers.
Conclusion: Probably Luigi is a diver.
It is improbable for the premises to be true and the conclusion false.
Wigmore (1931, p. 20) considered arguments of a kind that are commonly
used in collecting evidence in law.
Last week the witness A had a quarrel with the defendant B, therefore A is
probably biased against B.
A was found with a bloody knife in B’s house, therefore A is probably the
murderer of B.
Deductive, Inductive, and
the 3rd Type: Abductive?
Clue: Backward Reasoning by Explanation?
Defeasible Reasoning
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Birds fly.
Tweety is a bird.
Therefore Tweety flies.
Subject to exceptions (Tweety = penguin).
Based on non-absolute generalizations.
Nonmonotonic: valid arguments can become invalid by adding
premises.
Typical Argumentation Schemes
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Common schemes include such familiar types of argumentation as
argument from expert opinion, argument from lack of knowledge,
argument from example, argument from a rule to a case, argument
from a verbal classification, argument from position to know, argument
from analogy, argument from precedent, argument from correlation to
cause, practical reasoning, abductive reasoning, argument from
gradualism, and the slippery slope argument.
Other schemes that have been studied include argument from waste
(also called sunk costs argument), argument from temporal persistence
and argument from appearance.
In addition to presumptive schemes, it is possible to treat deductive and
inductive forms of argument as schemes.
All are linked arguments.
Deductive Linked Argument
Defeasible Linked Argument
Competence Center ELAN
Fraunhofer FOKUS
The Carneades Model of Argument
 Carneades models
 the structure of arguments
 the acceptability of statements
 burdens of proof (questioning, production and persuasion)
 proof standards, such as preponderance of the evidence
 Carneades is a
 computational model: the functions of the model are all
computable (i.e. recursive, decidable)
 Carneades has an argument mapping tool with a graphical user
interface: http://carneades.berlios.de/
Many Argumentation Support Tools
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Scheuer, O., Loll, F., Pinkwart, N. & McLaren, B.M. (2010). ComputerSupported Argumentation: A Review of the State of the Art.
International Journal of Computer-Supported Collaborative Learning.
5(1).
Two of them are Carneades and Araucaria.
Rationale is another one that can be very useful for philosophers.
Carneades (c.213 - c.128 B.C.)
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Leader of the Academic Skeptics.
Head of Plato’s (third) Academy.
Developed a theory enabling human action
despite the lack of perfect knowledge, based on
“reasonable grounds” and “probable”
inferences.
Carneades’ notion of probability corresponds
closely to what is now called defeasible,
plausible, or nonmonotonic reasoning.
Competence Center ELAN
Linked Arguments
Fraunhofer FOKUS
Competence Center ELAN
Convergent Arguments
Fraunhofer FOKUS
Competence Center ELAN
Serial
Arguments
Fraunhofer FOKUS
Competence Center ELAN
Pros and Cons
Fraunhofer FOKUS
Araucaria
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Araucaria is a software tool for analyzing arguments. It aids a user in
reconstructing and diagramming an argument using a simple point-andclick interface. The software also supports argumentation schemes, and
provides a user-customizable set of schemes with which to analyze
arguments.
Once arguments have been analyzed they can be saved in a portable
format called AML, the Argument Markup Language.
http://www.computing.dundee.ac.uk/staff/creed/araucaria/
Argument from Expert Opinion
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Major Premise: Source E is an expert in domain D containing proposition
A.
Minor Premise: E asserts that proposition A (in domain D) is true (false).
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Conclusion: A may plausibly be taken to be true (false).
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Application to Law
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Currently one of the most active areas of application is to law.
Researchers in AI and Law are prominent users of
argumentation tools, including Tom Gordon, Bart Verheij,
Henry Prakken, Trevor Bench Capon and Floris Bex.
Scheme from Expert Opinion
Corroborative Expert Opinions:
Linked and Convergent Arguments
Six Critical Questions
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Expertise Question: How knowledgeable is E as an expert source?
Field Question: Is E an expert in the field D that A is in?
Opinion Question: What did E assert that implies A?
Trustworthiness Question: Is E personally reliable as a source?
Consistency Question: Is A consistent with what other experts assert?
Backup Evidence Question: Is E’s assertion based on evidence?
Legal Expert Opinion Scheme
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Competence Premise (Ordinary Premise): E is an expert in knowledge
domain D.
Statement Premise (Ordinary Premise): E said the sentence S*.
Interpretation Premise (Ordinary Premise): S is a reasonable
interpretation of S*.
Domain Premise (Assumption): S is in D.
Depth of Knowledge Premise (Assumption): The knowledge of E about
D is deep enough to know about S.
Careful Analysis Premise (Assumption 3): E’s testimony S* is based on
his own careful analysis of evidence in this case.
Other Experts Premise (Exception): S is inconsistent with what other
experts in D say.
Credibility Premise (Exception): E is not credible.
Conclusion: S may plausibly be taken to be true.
Scheme for Practical Reasoning
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Major Premise: I have a goal G.
Minor Premise: Carrying out this action A is a means to realize G.
Conclusion: Therefore, I ought (practically speaking) to carry out this
action A.
Critical Questions for Scheme
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CQ1: What other goals do I have that should be considered that might
conflict with G?
CQ2: What alternative actions to my bringing about A that would also
bring about G should be considered?
CQ3: Among bringing about A and these alternative actions, which is
arguably the most efficient?
CQ4: What grounds are there for arguing that it is practically possible
for me to bring about A?
CQ5: What consequences of my bringing about A should also be taken
into account?
Lunesta Sleep Medication Ad
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The picture in the ad shows the head and shoulders of a young man
asleep, his head resting against the pillow.
In large print above the picture, the words “The sleep you’ve been
dreaming of.” are printed.
Below the picture it says, “Soothing Rest for Mind and Body.”
Below that, the text of the ad appears [as quoted].
“It’s what you’ve been craving. Peaceful sleep without a struggle. That’s
what Lunesta is all about: helping most people fall asleep quickly, and
stay asleep all through the night”.
Premises of Lunesta Argument
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Premise: my goal is to have peaceful sleep without a struggle.
Premise: taking Lunesta is the best means to have peaceful sleep
without a struggle.
Premise: Lunesta helps most people fall asleep quickly.
Premise: they stay asleep all through the night.
Argument Map of Lunesta Ad
Enthymemes
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An enthymeme is an argument with an implicit premise or conclusion.
All physicians are college graduates, so all members of the AMA are
college graduates.
MISSING PREMISE: All members of the AMA are physicians.
Roadside sign: “The bigger the burger, the better the burger. The
burgers are bigger at Burger King.”
MISSING CONCLUSION: The burgers are better at Burger King.
In the Lunesta ad, the conclusion is also implicit.
Normative Models of Dialog
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Arguments are taken in traditional logic, to consist of a set of premises
(statements) and a conclusion (another statement).
The dialog is a model represents the conversational setting in which an
argument was put forward for some purpose.
There are different types of dialog.
Each dialog has an opening stage, and argumentation stage and a
closing stage.
Classification of Dialogs
Dialog
Persuasion
Critical
Discussion
Information
Seeking
Interview
Negotiation
Advice
Solicitation
Inquiry
Scientific
Inquiry
Expert
Consultation
Deliberation
Public
Inquiry
Eristic
Quarrel
Types of Dialog
TYPE OF
DIALOG
Persuasion
INITIAL
SITUATION
Conflict of
Opinions
Need to Have
Proof
Conflict of
Interests
PARTICIPANT’S
GOAL
Persuade Other
Party
Find and Verify
Evidence
Get What You Most
Want
GOAL OF DIALOG
Information- Need
Seeking
Information
Acquire or Give
Information
Resolve or Clarify
Issue
Prove (Disprove)
Hypothesis
Reasonable
Settlement that Both
Can Live With
Exchange
Information
Deliberation
Co-ordinate Goals
and Actions
Decide Best Available
Course of Action
Verbally Hit Out at
Opponent
Reveal Deeper Basis
of Conflict
Inquiry
Negotiation
Eristic
Dilemma or
Practical
Choice
Personal
Conflict
Dialogue
Structure
Salmon’s Case
Salmon sold medicines in London. M’Kensie bought from him some pills for
rheumatism; after numerous doses he died. The medical men, on a
postmortem examination, affirmed that certain ingredients of these pills
had caused his death; and Salmon was indicted for manslaughter. But on
the trial he produced many witnesses, who had taken the same kind of pills
with much benefit; one witness affirmed that he had taken twenty
thousand of them within the past two years, to his great benefit! If these
circumstances were true, the inference was inevitable that the pills were
not lethal. But was the testimony to this circumstance true?
Key List of Statements in Salmon’s Case
(A) The medical man affirmed that certain ingredients of the pills had
caused M’s death.
(B) The medical man is an expert in medicine [implicit premise].
(C) Certain ingredients in the pills had caused M’s death.
(D) M’s taking the pills caused his death.
(E) Witness W testified that he took the same kind of pills and they caused
him no harm.
(F) Witness W is in a position to know about the effects of the pills on him
[implicit premise].
(G) If the pills caused no harm to W, the pills were not lethal [implicit
premise].
(H) The pills were not lethal.
Diagram of Salmon Case
How Arguments are Evaluated
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Burdens of proof and standards of proof, along with argument weights,
determine how to evaluate the argumentation in a dialog.
The burden and standard of proof are set at the opening stage, and
depend on the type of dialog.
In the argumentation stage, each side presents reasons supporting its
view and attacks the opposed view by raising critical questions and
rebuttals.
The burdens and standards are then applied at the closing stage to
determine which side won and which lost the dialog.
Defining Burden of Proof
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Burden of proof has three components: (a) a contained proposition
representing one arguer’s claim to be proved (b) which arguer
(proponent or respondent) has that thesis, and (c) a standard of proof
required for proving that thesis.
There are different types of burden of proof recognized in law.
Two Burdens of Proof in Law
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Burden of Persuasion (also called legal burden of proof): in a murder
trial, the prosecution must prove the charge that the defendant
committed murder.
Evidential Burden (also called burden of production): if a person
accused of burglary is found carrying “burglarious implements”, an
evidential burden is placed on him to give some explanation of why he
had such articles in his possession. If he fails to do so, the conclusion
can be drawn he was carrying them to commit burglary.
Standards of Proof
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(Gordon & Walton, 2009)
The standard of scintilla of evidence iff there is one argument
supporting the claim.
The preponderance of the evidence standard is met iff scintilla of
evidence standard is met and the weight of evidence for the claim is
greater than the weight against it.
The clear and convincing evidence standard is met iff the
preponderance of the evidence standard is met and the weight of the
pro arguments exceeds that of the con arguments by some specified
threshold.
The beyond reasonable doubt standard is met iff the clear and
convincing evidence standard is met and the weight of the con
arguments is below some specified threshold.
These standards are defined in the Carneades model.
Locutions and Speech Acts
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Statements and questions are locutions.
Making an assertion is a speech act.
Asking a question is a speech act.
Asking for an explanation is an even more specific speech act.
Putting forward an argument is a speech act.
Offering an explanation is a speech act.
Speech Act Moves in a Dialogue
Goal of Dialogue
Sequence of Moves
Turn-taking
Respondent's Move
Speech Act
Post-condition
Proponent's Move
Pre-condition
Initial Situation
Speech Act
Dialogue Models of Explanation
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The dialogue model is not restricted only to argumentation.
An explanation can be modeled as a dialogue between two agents in
which one agent is presumed by a second agent to understand
something, and the second agent asks a question meant to enable him
to come to understand it as well.
The dialectical 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.”
Argument or Explanation?
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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.
Conditions in the Dialogue Model
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Dialogue Conditions: explainee asks question of a specific form asking
about what is assumed to be a known fact S.
Understanding Conditions: explainee does not understand S, but
assumes that explainer understands S.
Success Conditions: explainer by what she says brings the explainee to
understand S.
Rules for Explan Dialogue System
 Opening: when explainee makes an explanation request for S
(accepted fact).
 Locution Rules: defines different speech acts (kinds of moves)
that are allowed.
 Dialogue Rules: show which move must follow each previous
kind of move.
 Success Rules: show when transfer of understanding has been
achieved.
 Closing1: when explainee says ‘In understand it’.
 Closing2: explainee shows understanding through testing.
Explanation in a Sequence of Dialogue
Event Taken
as Factual
by Both
Parties
Attempt
Judged to be
Successful
or not by
Respondent
Something
Perplexing
to
Respondent
about Event
Not Successful
Explanation
Dialogue
Concluded
Respondent
asks
Proponent for
Help in
Understanding
Successful
Proponent
Offers
Explanation
Attempt
References