An argument is a set of claims where one is asked to accept one of them-the conclusion, on the basis of its following from the other(s)-the premise(s).
As such, there are two main things to look at in regards to any argument. One, are the premises true? Two, is the argument of such a form that the premises being true would justify one’s believing the conclusion as well?
When we talk about logical “fallacies,” say in a critical thinking class, we are referring to some of the ways that the premises or the structure of an argument can be flawed that are common enough to have been given names over the years.
A straw man fallacy, for instance, sometimes uses as a premise a misrepresentation of the position it is arguing against. For example:
* Premise: The health care reform bill before Congress will create panels of government bureaucrats to decide when people are too old any more to be useful and so should not be given medical care.
* Conclusion: The health care reform bill before Congress should be opposed.
The problem with this argument is that the premise grossly distorts, if not flat out lies about, the health care reform bill. If it were true, it does indeed provide a pretty good reason to oppose the bill, all else being equal, but it’s not.
Other fallacy types don’t pertain so much to the truth or falsity of the premises, as to the structure of the argument. In an ad hominem attack, for instance, even if the premise is true, the problem is that the conclusion doesn’t follow from it. For example:
* Premise: Professor Pettigrew is a known pot smoker and fornicator.
* Conclusion: Professor Pettigrew’s claims about the origins of the Cold War are bogus.
In this case, even if the premise is true, it fails to give one sufficient reason to accept the conclusion.
The categories of fallacies that have been given names, however, cannot be expected to encompass every possible error, every possible deception that can occur in human reasoning and argumentation.
Therefore, I like to think of a couple of fallacy categories as not having such specific meanings as the others, but instead functioning as “miscellaneous” categories.
So where the problem with an argument is that one or more of the premises is false or at least dubious for some reason, but it doesn’t fit well in any other fallacy category, we can call that an instance of the questionable premise fallacy.
For example, if I argue that the Rolling Stones are the greatest band ever because they were led by John Lennon and he was such an amazing musician and showman for them, it’s a weak argument because I’ve confused the Beatles and the Rolling Stones, and falsely claimed as a premise that Lennon was with the Stones. But there’s no special fallacy name for misremembering British bands. So we’d say the fallacy this argument commits is questionable premise, rather than some more specific fallacy.
If the problem with an argument instead is that it is not of a structure such that the premises-even if true-would justify accepting the conclusion, and it doesn’t fit well in any other fallacy category, we can call that an instance of the non sequitur fallacy.
“Non sequitur” is a Latin phrase meaning “it does not follow.” You might also see this fallacy category referred to as irrelevant reason in some sources.
For example, many, many years ago, the South African government, when it was an apartheid regime that oppressed and basically enslaved its black majority for the benefit of its small white minority, hired as its public relations and lobbying liaison in the United States a black American named William Keyes. When Keyes was asked how he could stoop so low as to accept such a position, he responded that “the troubles in South Africa are among the most important facing the world today.”
Broken down into premise and conclusion, his position in effect was:
* Premise: The troubles in South Africa are among the most important facing the world today.
* Conclusion: It is not dishonorable for me to accept a job working on behalf of the apartheid government of South Africa.
Almost everyone would agree the premise was true. But the problem is it’s irrelevant to the conclusion. It perhaps sounded at the time like Mr. Keyes was saying something responsive to the question, but if you actually stop and think about his argument, it’s nonsense.
If there is no other fallacy category to fit Keyes’s argument into, then we can consider it an instance of the non sequitur fallacy.
So in conclusion, think of questionable premise and non sequitur as “none of the above” categories to use when either there is a problem with the premise(s) or the form of an argument respectively, but there is no more specific fallacy category that applies.