And Brutus is an Honorable Man (Fallacies Part 4)

Red Herrings



Red herrings are responses to an original argument that don’t address the substance of the argument — they’re distractions. The various forms of ad hominem are attempts to discredit the argument by discrediting the arguer. But what about the reverse? What if the claim is that the argument is true because the arguer is an authority?

Argument From Authority

In the argument from authority, we claim that a statement is true because of the person who said it. The general form of this argument goes thusly:

1. Person A makes claim C.
2. Person A has particular authority or credentials in the area of claim C, or is a unique position to know the truth about claim C.
3. Therefore, claim C is true.

It goes by three different Latin names, each of which gives a slightly different flavor to the argument.

Argumentum ad verecundiam is generally translated as “argument from respect,” but verecundiam really means modesty or shyness, a cynical formulation by the phrase’s creator, John Locke. “When men are established in any kind of dignity, it is thought a breach of ‘modesty’ for others to derogate any way from it, and question the authority of men who are in possession of it.” 

On June 3, 2011, Sarah Palin famously spoke of Paul Revere, saying in part, “He…warned uh, the British that they weren't gonna be takin' away our arms….” The resultant fight that broke out on the Paul Revere Wikipedia page is about power. The criticism of Palin was treated by her adherents as a form of lèse majesté — as if it were improper and unfair to do anything other than accept her formulation as fact.

Argumentum ad potentiam means “argument from power,” in which the temporal authority of the speaker is the evidence offered for the truth of the statement. That’s what Marc Anthony mocks when he says, “But Brutus says he was ambitious. And Brutus is an honorable man.”

The third version of argument from authority is ipse dixit, or “he himself has said it.” It’s simply a bare assertion, a statement offered without evidence or factual support. You are supposed to believe it purely on the word of the person making the statement. The rule, for example, that one must not end a sentence with a preposition comes from 18th century grammarian Robert Lowth — who made it up.

Of course, it’s not wrong to have your opinions and beliefs influenced by people with particular authority and education. In fact, it’s hard to see how we could avoid doing so. We don’t have the time to learn everything ourselves, and in some cases we don’t have the capacity, tools, or resources. The fact that a given authority believes something can be a reason for us to believe it ourselves, at least as a provisional hypothesis until something better comes along.

What it doesn’t do is constitute a formal proof. For a formal proof, you have to provide evidence of the proposition itself, rather than a list of the credentials of the person making the statement.

Fallacies (a New Series in the Manner of Cognitive Biases) - Part 1

As a follow-up to my series on cognitive biases, here’s the start of a new one: a description of classical fallacies. For the purposes of this discussion, a fallacy is an opinion or position based on invalid reasoning. The conclusion itself may not be wrong, but the argument offered in support of it is wrong.

“He plays a doctor on TV; he endorses this medical product; therefore, the medical product is good” is fallacious not because the medical product being touted is necessarily not good, but because it’s ad verecundiam, an appeal to an authority outside the authority’s area of expertise. If the same authority made a statement about the profession of acting, however, it wouldn’t be ad verecundiam because the actor presumably has standing on the subject.

Just because the actor has standing, however, doesn’t constitute a final proof that the proposition is true. At most, it counts as an evidence point — but it’s a logically valid one.

For the list of fallacies, I’m starting with the list on Wikipedia. There’s another extensive list at The Nizkor Project.  The examples and discussion are my own.

Fallacies come in two basic flavors.

Formal fallacies, as the name suggests, are errors of form: regardless of the contents of the argument, or the truth of any of the statements, the argument is invalid on its face.  An appeal to probability is one such fallacy: the idea that if something could happen, it necessarily will happen.

There are subsets of formal fallacies. Propositional fallacies are structural errors in logic.  “It’s raining or it’s Tuesday; it’s not raining, therefore it’s Tuesday” is a propositional fallacy (affirming a disjunct). It may not be raining, but that doesn’t make it Tuesday.

Syllogistic fallacies also fall into the category of formal fallacies. “Some cats are black; some black things are televisions; therefore some cats are televisions” involves an illicit treatment of the minor term (you can’t assume that the set of televisions and the set of cats have common members because they share a particular color).

Informal fallacies are not fallacious because of their structure, but usually because of their content. Ad verecundiam and its kissing cousin ad hominem both use a personal characteristic to prove or disprove a proposition without establishing that the personal characteristic in question actually determines whether the conclusion is true or false.

I learned a lot doing the cognitive biases series, and I hope to learn a lot on this project as well. If you’ve seen any great examples of any of these fallacies, please let me know.