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Arguments from Ignorance
Arguments from Ignorance explores the situations in which the argument from ignorance (also known as the lack-of-knowledge inference, negative evidence, or default reasoning) functions as a respectable form of reasoning and those in which it is indeed fallacious. Douglas Walton draws on everyday conversations on all kinds of practical matters in which the argumentum ad ignorantiam is used quite appropriately to infer conclusions. He also discusses the inappropriate use of this kind of argument, referring to various major case studies, including the Salem witchcraft trials, the McCarthy hearings, and the Alger Hiss case. This book makes an original contribution in the areas of argumentation theory and informal logic, contending that, despite its traditional classification as a fallacy, the argument from ignorance is a genuine, very common, and legitimate type of argumentation with an identifiable structure. But the book is also interdisciplinary in scope, explaining many widely interesting and controversial subjects in artificial intelligence, medical education, philosophy of science, and philosophy of law in a clear way that makes it accessible to a broad range of readers.
- GenresPhilosophy
326 pages, Hardcover
First published January 1, 1995
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About the author
Douglas N. Walton
65 books46 followersDouglas Neil Walton (PhD University of Toronto, 1972) is a Canadian academic and author, well known for his many widely published books and papers on argumentation, logical fallacies and informal logic. He is presently Distinguished Research Fellow of the Centre for Research in Reasoning, Argumentation, and Rhetoric (CRRAR) at the University of Windsor, Canada, and before that (2008-2014), he held the Assumption Chair of Argumentation Studies at the University of Windsor. Walton’s work has been used to better prepare legal arguments and to help develop artificial intelligence. His books have been translated worldwide, and he attracts students from many countries to study with him. A special issue of the journal Informal Logic surveyed Walton’s contributions to informal logic and argumentation theory up to 2006 (Informal Logic, 27(3), 2007). A festschrift honoring his contributions, Dialectics, Dialogue and Argumentation: An Examination of Douglas Walton’s Theories of Reasoning and Argument, ed. C. Reed and C. W. Tindale, London: College Publications, 2010, shows how his theories are increasingly finding applications in computer science. A list of titles of many of Walton’s books is given below. Links to preprints of many of his published papers can be found on the website
http://www.dougwalton.ca
http://www.dougwalton.ca
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August 20, 2018
The Shape of the Unknown
An accessible philosophical treatise on the logic and rhetoric of making statements about the unknown. Traditionally appeals to ignorance are treated as fallacies, ie: the lack of evidence for X (where X is God, flying saucers, the presence of good will, whether X has criminal intent...) is insufficient to prove or disprove ~X. Walton surveys some 50 modern textbooks in Logic going back to the 17th century's The Art of Thinking: Port-Royal Logic as well as Copi's Introduction to Logic (which I used in university) and found that they all spent very little time examining argumentum ad ignorantiam. He concludes that the subject was in sore need of review.
Walton shows that in certain cases such as closed complete systems of knowledge or in courts of law that using Arg. from Ig. absence of evidence may indeed be used as proof. For the former he gives the example of searching for a commercial flight from Winnipeg to Amsterdam in a computer database. We know, or at least believe, that the database lists all known flights, therefore the absence of a such a flight in the database makes it highly plausible that no such flight exists. Similarly in a court of law where innocence is presumed, the lack of evidence will result in a verdict of innocent whereas the occur in a a jurisdiction based on Roman Law and the burden of proof would be on the defendant. A third possibility is to realize that there is a third option - to step outside a conclusion of true or false and to "suspend commitment" (pp154), the legal equivalent being the Scottish verdict of "Not Proven".
Central to Walton's discussion is the notion that argumentation takes place in different contexts. Ch 6 consists of a wonderful categorization of different forms dialog (see also Walton's Media Argumentation: Dialect, Persuasion, and Rhetoricfor a similar treatment). Arguments using Arg. from Ig. may be seen as either deduced from knowledge (epistemic), inductive or useful as a means of influencing discussion (dialectic). Ch 7 examines the idea of Burden of Proof in greater detail, both as an ethic and as a tactic. There's a nice little decision tree on pp294 that summarizes the ideas presented.
Another strength of the book is the expert selection of relevant examples and case studies including a look at the Salem witchcraft trials, arguments for and against Alger Hiss being a Soviet Spy and the safety of silicon breast implants. Another good example would be the scenario of "the dog who didn't bark" - here the lack of evidence could suggest that the intruder was well known to the dog. The author also examines situations where the onus of proof has changed over time, for example in the requirements of testing for adverse side effects of a new drugs. Depending on circumstance, where knowledge is incomplete, had a degree of fallibility or is simply unavailable, prudence may require the acceptance of an argument from ignorance, so that wherein might not be known that a drug is potentially harmful, one should presume that it is. Conversely, if the patient is nearing death, circumstances might favour using that same drug in spite of the risk.
Socrates once said that the only true wisdom is in knowing what you do not know. Walton shines a light on a corner of this idea by examining the limits to which a lack of knowledge can be allowed to inform. It's a worthwhile read that illuminates meta-argument, the thinking process and the art of debate. Recommended.
An accessible philosophical treatise on the logic and rhetoric of making statements about the unknown. Traditionally appeals to ignorance are treated as fallacies, ie: the lack of evidence for X (where X is God, flying saucers, the presence of good will, whether X has criminal intent...) is insufficient to prove or disprove ~X. Walton surveys some 50 modern textbooks in Logic going back to the 17th century's The Art of Thinking: Port-Royal Logic as well as Copi's Introduction to Logic (which I used in university) and found that they all spent very little time examining argumentum ad ignorantiam. He concludes that the subject was in sore need of review.
Walton shows that in certain cases such as closed complete systems of knowledge or in courts of law that using Arg. from Ig. absence of evidence may indeed be used as proof. For the former he gives the example of searching for a commercial flight from Winnipeg to Amsterdam in a computer database. We know, or at least believe, that the database lists all known flights, therefore the absence of a such a flight in the database makes it highly plausible that no such flight exists. Similarly in a court of law where innocence is presumed, the lack of evidence will result in a verdict of innocent whereas the occur in a a jurisdiction based on Roman Law and the burden of proof would be on the defendant. A third possibility is to realize that there is a third option - to step outside a conclusion of true or false and to "suspend commitment" (pp154), the legal equivalent being the Scottish verdict of "Not Proven".
Central to Walton's discussion is the notion that argumentation takes place in different contexts. Ch 6 consists of a wonderful categorization of different forms dialog (see also Walton's Media Argumentation: Dialect, Persuasion, and Rhetoricfor a similar treatment). Arguments using Arg. from Ig. may be seen as either deduced from knowledge (epistemic), inductive or useful as a means of influencing discussion (dialectic). Ch 7 examines the idea of Burden of Proof in greater detail, both as an ethic and as a tactic. There's a nice little decision tree on pp294 that summarizes the ideas presented.
Another strength of the book is the expert selection of relevant examples and case studies including a look at the Salem witchcraft trials, arguments for and against Alger Hiss being a Soviet Spy and the safety of silicon breast implants. Another good example would be the scenario of "the dog who didn't bark" - here the lack of evidence could suggest that the intruder was well known to the dog. The author also examines situations where the onus of proof has changed over time, for example in the requirements of testing for adverse side effects of a new drugs. Depending on circumstance, where knowledge is incomplete, had a degree of fallibility or is simply unavailable, prudence may require the acceptance of an argument from ignorance, so that wherein might not be known that a drug is potentially harmful, one should presume that it is. Conversely, if the patient is nearing death, circumstances might favour using that same drug in spite of the risk.
Socrates once said that the only true wisdom is in knowing what you do not know. Walton shines a light on a corner of this idea by examining the limits to which a lack of knowledge can be allowed to inform. It's a worthwhile read that illuminates meta-argument, the thinking process and the art of debate. Recommended.
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