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
On Deceptively Edited Video
“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.
On Withholding Data
The paper I just published — “Climate warming increases extreme daily wildfire growth risk in California” — focuses exclusively on how climate change has affected extreme wildfire behavior. I knew not to try to quantify key aspects other than climate change in my research because it would dilute the story that prestigious journals like Nature and its rival, Science,want to tell.
Patrick T. Brown, “I Left Out the Full Truth to Get My Climate Change Paper Published” at The Free Press (Septermber 5, 2023).
Withholding exculpatory evidence in a murder trial
“Kyle Rittenhouse’s legal team accused prosecutors of holding back key video footage that is at the heart of their case in a formal motion for a mistrial, court documents show. … Prosecutors gave the defense a hard-to-see, low-res version in a 3.6MB file — less than a third of the high-res file they actually had, the motion states. They only got the better-quality clip, already used by prosecutors, on Saturday, after testimony had concluded, the motion stated.
“Prosecutors withheld high definition footage“, in The New York Post (November 17, 2021).
In the Kyle Rittenhouse case, video evidence was central to exonerating him. Withholding or degrading video evidence in a murder trial is paradigmatic example of suppression or exclusion.
A key piece of evidence was withheld in another murder trial, that of Noura Jackson.
The evidence was a handwritten note from a key witness at trial. His name is Andrew Hammack. He was the only person who testified that Noura was at the scene of the crime at the key period in which her mother was killed and a time when Noura was unaccounted for. … The Tennessee Supreme Court, when it reversed Noura’s conviction, found that the defense could have used this note to completely undermine Andrew Hammack’s testimony
“Guilt By Omission“, All Things Considered, NPR (August 4, 2017).
On partial plaudits on movie posters
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 positive word or phrase — “ingenious”, “mindbending” — even from reviews which were negative on the whole.
On citing selected studies
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.
On taxes and emphasizing parts instead of the whole
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.
Conversely, “tax the rich” advocates will only ever offer tax rates instead of tax sums paid.
Warren Buffett has famously stated that he pays a lower tax rate than his secretary, but as this report documents this situation is not uncommon. This situation is the result of decades of the tax system being tilted in favor of high-income households at the expense of the middle class. Not only is this unfair, it can also be economically inefficient by providing opportunities for tax planning and distorting decisions. The President has proposed the Buffett Rule as a basic rule of tax fairness that should be met in tax reform.
The Obama Administration, “The Buffet Rule” (April 2012).
Let’s change the rigged tax code so The Person of the Year will actually pay taxes and stop freeloading off everyone else.
Senator Elizabeth Warren, via Twitter (December 13, 2021).
Buffet apparently paid $23.7 million in taxes from 2014-2018, exponentially more than his secretary, and “the rich” account for the vast majority of US taxes paid. Elon Musk paid more in taxes in 2021 than anyone has ever paid.
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 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 sharing all the data from an experiment
On intentional and unintentional suppression…
On the ideal of total evidence…
On whether it is a logical fallacy, strictly speaking…
On Misusing the Ellipsis…