Fallacy of Exclusion and Suppressed Evidence
Important evidence which would undermine an inductive argument is excluded from consideration. “In an induction, the total relevant information needs to be examined. The fallacy occurs when relevant evidence which would undermine an inductive argument is excluded from consideration. The requirement that all relevant information be included is called the principle of total evidence.” (Chhanda, Logic: Informal, Symbolic, and Inductive, p. 48.)
Examples
- “After dismissing election monitors, an official in Fulton County, Georgia continued counting in the dark of night. This is the ‘smoking gun’ proving election fraud in the 2020 US presidential election.” Following sworn affidavits and video evidence, Rudy Giuliani and Jacki Pick testified before the Georgia state legislature that the video shows fraud. However, the video was highly edited and failed to include extended footage of the ballots in question being brought in and boxed in the light of day.
- “The police found a dead body with three bullet wounds. It would be a safe, albeit not mathematically certain, conclusion that the person found by the police died because of his gunshot wounds — that is, unless we also knew that the body was missing its head. Although it is still possible that the victim died of gunshot wounds and that the decapitation was inflicted postmortem, it is equally possible that the manner of his death was decapitation and someone administered the bullet wounds postmortem for some other purpose. The fallacy of exclusion forces the decision maker into reaching a false conclusion owing to lack of relevant alternative evidence. (Pedneault, Rudewicz, Silverstone, Sheetz, Forensice Accounting and Fraud Investigation for Non-Experts (John Wiley & Sons: 2012), pp. 215-6)
- “Many movie ads, for example, include positive comments from critics, such as ‘One of the year’s best movies’ or ‘Hilariously funny — Gene Siskel gave it a thumbs-up.’ But when was the last time you saw an ad for a movie that mentioned that Roger Ebert gave it a thumbs down?” (Carrick, The Persuasive Pen, p. 183.) » A related example is the growing phenomenon of movie trailers excising just a word or phrase — “ingenious”, “mindbending” — even from reviews which were negative on the whole.
- Sandra Silberstein recounts a personal example: “‘Imagine the real suffering and grief of people in other countries. The best way to begin a war on terrorism might be to look in the mirror.’ One interesting thing I want to observe about that quote is where they chose to begin it. It’s a quote from a speech I made at a peace rally at MIT, shortly after September 11th. And I took as my theme the difficulty of imagining the real suffering of other people. And just before that quote they select, I talked about how difficult it is for us to imagine the suffering of the people at the World Trade Center as they were dying. And then I went on from there to invite the audience to try and imagine the suffering of people in Afghanistan if we are to go and declare war on the people of Afghanistan. Of course, the quote is carefully cut so it seems that I only talk about the suffering of people in other countries and not about the suffering of Americans as well…” (Silberstein, War of Words, p. 137.)
- “When someone makes an argument but leaves out a particular fact that would contradict the conclusion, they commit the Fallacy of Exclusion. This was committed on a grand scale by a 2004 Oxford study on the abortion-breast cancer link. Considered by many pro-abortion groups as the ‘end-all’ study on the matter, it consisted of a comprehensive review of over 50 studies on the possible link of abortion to breast cancer. While the conclusion was that no such link existed, the study’s lead author, Valarie Beral, admitted to the Washington Post that they excluded many studies that had found a link and contradicted their conclusion, citing only an unproven belief that women with breast cancer ‘are more likely then healthy women to reveal they had an abortion, leading to the conclusion that there are more abortions among this group.’ The failure to include data that compromised the desired conclusion is evidence of a Fallacy of Exclusion.” (Nowak, Guerilla Apologetics for Life Issues, pp. 14-5.)
- “Take, for instance, the accounts widely circulated in 2000 about how the tax burden has shrunk to its lowest level in 40 years, with those earning under $30,000 (half of all taxpayers in the year 2000) paying a mere 2 percent of all income taxes. The strong implication of these stories was that the bottom half of taxpayers cannot complain, since they pay such a small amount of all taxes. Overlooked (on purpose? accidentally? out of ignorance?) was the fact that other kinds of taxes are a much greater burden to the bottom 50 percent of income earners than are income taxes. … [M]ost of these stories failed to note that when all taxes whatsoever are added up, the bottom half of the population pays a higher percentage of their income in taxes than do those in the very high-income groups.” (Kahane & Cavender, Logic and Contemporary Rhetoric, pp. 62-3.)
- Frequently encountered is the situation where one piece of evidence is discounted because by using it, the result does not fit the forgone conclusion. … People … draw conclusions first, then select evidence that supports the conclusions and discount evidence that does not. A common example is the interpretation of land descriptions. People believe they already know what they own; therefore, regardless of the wording in the the description, the conclusion must be what they meant when they wrote it, despite what they actually said. As the court stated in the case of Smart v. Huckins, “it is a matter of fitting the deed to the land, not the land to the deed.” (Wilson, Forensic Procedures for Boundary and Title Investigation (John Wiley & Sons: 2008), p. 50).
Critique
Give the missing evidence and show that it changes the outcome of the inductive argument. Note that it is not sufficient simply to show that not all of the evidence was included; it must be shown that the missing evidence will change the conclusion. “Anyway, the point of becoming familiar with the fallacy of suppressed evidence is to sharpen one’s ability to spot cases in which relevant evidence is being passed over, whether by others or by ourselves. We need, in particular, to learn how to carry through reasoning so as to see whether all likely relevant information has been considered.” (Kahane & Cavender, Logic and Contemporary Rhetoric, p. 62.)
Commentary
On overlooking evidence because of an ideological bias…
On intentional and unintentional suppression…
On the ideal of total evidence…
On whether it is a logical fallacy, strictly speaking…
On Misusing the Ellipsis…