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Content created: 2022-05-12
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Logical Errors

That Can Be Hard To Avoid

(and how to avoid them)

Page Index

  1. Overview
  2. Venerable (Latin) Logical Errors
    Argumentum ad baculum Argumentum ad hominem Argumentum ad populum Argumentum ex nihilo Non sequitur Petitio principi Post hoc ergo propter hoc Stare decisis Tu quoque
  3. Less Venerable (English) Logical Errors
    Bad argument fallacy Bifurcation fallacy Correlation & causation fallacy Mistaken reversal fallacy Whataboutism Bothsidesism)


People tend to reason badly, so badly, that a great many logical errors have long established Latin names. Latin makes them venerable, of course, but they are still stupid.

Whatever the case, you need to know about common logical errors.

Here is an alphabetical list of such idiocies with venerable Latin names, followed by some for which I have not discovered common Latin names. (Readers of this page may also be interested in a page on Quick Essays on Social Theory, especially Interpreting Motivation.)

List I: Venerable Logical Errors (With Latin Names)

    Argumentum ad baculum
    If you keep saying it’s too hot to work, I’ll fire you and hire somebody else.
  1. Argumentum ad baculum (“arguing at the cudgel”) = offering an inducement for agreeing and/or threatening negative consequences for disagreeing, without regard to the logical properties of the position taken.
    For example:
  2. Argumentum ad hominem
    It’s hard to take somebody seriously who’s covered with tattoos.
  3. Argumentum ad hominem (“arguing at the person”) = attacking a person’s character or personal characteristics rather than his or her arguments.
    For example:
  4. Argumentum ad populum:
    As you can see from its sales, the Harry Potter series is the greatest literary work ever.
  5. Argumentum ad populum (“arguing to popular usage”) = arguing that because an opinion is widespread it must be true.
    For example:
    Sometimes the “populum” is very restricted in order to get a majority within it, falsely suggesting statistical significance. For example:
  6. Argumentum ex nihilo:
    Your brother is guilty; he has no alibi.
  7. Argumentum ex nihilo (= ex silencio) (“arguing from nothing, from silence”) = arguing that a proposition is right because it hasn’t been proven wrong. Sometimes summarized as “the absence of evidence is not evidence of absence.”
    For example:
  8. Non sequitur:
    There’s a lot of traffic; people must all be going to church.
  9. Non sequitur (“it does not follow”) = intriducing a statement that does not actually have anything to do with its premise (although one may be insinuated).
    For example:
  10. Petitio principi:
    People voted him into office because he was the most popular candidate.
  11. Petitio principi “consulting the premise” = assuming as fact what one is trying to discover or demonstrate (= begging the question, or circular reasoning)
    For example:
  12. Post hoc ergo propter hoc:
    As soon as he was elected a wealthy donor bought him a mansion.
  13. Post hoc ergo propter hoc “after that thing, therefore because of that thing” = arguing that what precedes must be the cause of what follows, even if no mechanism can be adduced by which they may be connected.
    For example:
  14. Stare decisis:
    We can don’t have enough judges to retry a lot of cases just because of somebody inventing a better DNA test, so it’s better just to let the punishments play out.
  15. Stare decisis (“to stand by what was decided”) = refusing to overturn an earlier decision because it already exists.
    In law this refers to a court refusing to overturn an earlier decision (called “settled law”), usually in the interest of stability, with occasional exceptions when the earlier decision is very, very clearly outdated or absurd. US Supreme Court justice Louis Brandeis wrote in 1932: “In most matters it is more important that the applicable rule of law be settled than that it be settled right.”
    For example:
    In the realm of science or logic, stare decisis refers to sticking to a standing paradigm as long as possible, even in the face of evidence that it is almost certainly wrong. One legitimate reason to do so is that it works much of the time and there is no better paradigm (or no better paradigm in a given context). Another is financial commitment.
    For example:
  16. Tu quoque:
    A lot of you also buy a little something for yourselves in order to clean out the budget by the end of fiscal year.
  17. Tu quoque (“you’re another”) = arguing that the opponent does the same thing and therefore his or her criticism should be ignored. (In other words, “everybody does it.”)
    For example:

List II: Less Venerable Logical Errors (Without Latin Names)

    Bad argument falacy:
    They couldn’t prove where the money went, so we think he is honest.
  1. Bad argument fallacy = arguing that because an argument is flawed, its conclusion is therefore wrong or that because an argument against a conclusion is poorly made, the conclusion is therefore right
    For Example:
  2. Bifurcation falacy:
    Yes or no: Was she rich?
  3. Bifurcation fallacy or False dichotomy = asking the listener to select between two options, one or both of which are in fact wrong or dangerously oversimplified, or when there are other logical possibilities or information is lacking. (This is a common idiocy in courts and Congressional hearings.)
    For example:
  4. Correlation & causation fallacy:
    Students who take Latin never become juvenile delinquents, so Latin should be a school requirement.
  5. Correlation & causation fallacy = arguing that phenomena that co-occur must therefore have a causal relationship in one direction or the other.
    For example:
  6. Mistaken reversal fallacy:
    They never come in on Wednesday; I don’t see them so today must be Wednesday.
  7. Mistaken reversal fallacy = arguing that “if A then B” means “if B then A.”
    For example: Premise: “If it is sunny, then they are playing baseball.” This says nothing about what they are doing when it is not sunny.
    This does not mean:
  8. Bothsidesism:
    There were good guys and bad guys, and both took some knocks, so there is no point in blaming anybody.
  9. Whataboutism or Bothsidesism = arguing that the behavior of one party shold be unexamined because another party did something comparable or more extreme.
    For example:

Now you know.

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