Informal Logic 101: How to Think and Argue Better, Part 8

Part 8: Validity and Clarity

“Most of the arguments to which I am party fall somewhat short of being impressive, owing to the fact that neither I nor my opponent knows what we are talking about.”  — Robert Benchley, American columnist & actor

Hey, folks! Ready for another lesson in logic? Of course, you are!!

In A World of Difference, Prof. Kenneth Samples warns that these first three fallacies are often resorted to when people are arguing for a particular worldview (i.e., a belief system). Unfortunately, they betray weaknesses in their argument. You’ll see what he’s talking about in a moment. Let’s get the Latin stuff out of the way first, shall we?

Annoy a Liberal -- Use Facts & LogicArgumentum ad vericundiam (“an appeal to an untrustworthy authority”)

Appealing to an authority is a great way to lend support to one’s case, though it probably doesn’t “prove” it by itself. When a true authority speaks on something within their area of expertise, we should give what they say due consideration. However, not everyone cited as an authority on something is an actual authority on that subject. It is also possible that, while having relevant credentials, the person or group appealed to is not always to be trusted.

Regarding the first instance, Richard Dawkins comes to mind. Dawkins is, of course, one of the prominent “new atheists” and media/science darling of the religion-is-bad/science-is-everything set. They love to quote his sage observations, scientific smackdowns, and witty snarks re the benighted “creationists” and religion in general. However, as an evolutionary biologist and ethologist who has studied and taught zoology, he is entirely out of his ken regarding theological and philosophical arguments, and it shows. True, he had “a normal Anglican” childhood, and I’m sure some philosophy of science was included in his graduate work. He may have also read a few things over the years on these topics. (In fact, philosopher and fellow-“new atheist” Daniel Dennett is a friend and cohort.) But, as far as serious study goes, Dawkins is no more an expert in the areas of philosophy and theology than I am. (The phrase “just enough knowledge to be dangerous” comes to mind.) So, quoting Dawkins on these subjects as support of an argument is of dubious value, at best. But, this is more about being unqualified than intentionally deceptive.

As for untrustworthy “authorities”, one obvious example is the various supermarket tabloids (e.g., the National Enquirer). These rags are known for having often unreliable sources, even making up stories, and being generally unscrupulous. Yet, some people still read them and believe the “news” articles. If someone tells me they believe Elvis is still alive because of all the sightings they read about in the tabloids, I’m not going to give it much credence. I will also be highly suspicious of other things the person tells me, because their judgment about such things is in question. There are plenty of similar examples of questionable news sources on the internet, including many on science, politics, and religion — the three main topics of this blog. A friend of a friend on Facebook often dismisses quotes and claims based on certain websites by implying — usually with an “LOL” and a condescending remark — that they are untrustworthy sources and, therefore, not worth consideration. Unfortunately, I think it has become a knee-jerk reaction with him and betrays his own biases.

One last point on this…. Bias and prejudice can be at work in this circumstance as in many others. We need to beware of either or both in ourselves, as well as how they might influence others’ beliefs and interpretations of data.

Argumentum ad ignorantiam (“an appeal to ignorance”)

This fallacy happens when a conclusion is reached, despite the fact that the premises haven’t proven anything definite. If someone to keep arguing in favor of X because it hasn’t been definitively proven false, they are guilty of an appeal to ignorance. Examples of this include conspiracy theorists and those who ardently believe in things like Bigfoot and paranormal/extradimensional explanations for the “Bermuda Triangle” phenomena. Nothing (at least, to their minds) has decisively shown these things to be false, non-existent, or totally explained by normal/natural events, so they point to the “evidence” and insist that the more fantastic explanations are true.

“No one has proven the Loch Ness Monster is a hoax or merely the product of peoples’ imaginations or wishful thinking, so I choose to believe she’s real. Hopefully, one day we’ll be able to show the world….”

Similarly, if someone argues against X simply because it hasn’t been definitively proven true, they are guilty of an appeal to ignorance. Many atheists argue this way against the existence of God. Despite the many, quite rational arguments in favor of the existence of a supernatural Supreme Being, there will always be those that reject the probability, or even the possibility, that there is a God. The reasons are manifold and would be a good topic for another post. But, the point here is that they feel they can hold onto this view unless & until there is “absolute proof” of God. (One has to wonder what that would look like for one so dead-set against the idea.)

The problem for those who use such “reasoning” is that it’s really no support for their case, at all. Just because you lack knowledge regarding a particular point, you can’t assume the opposite is true. All it “proves” is that you lack knowledge on that particular point… period. The premise(s) prove(s) nothing, so the conclusion cannot be made. If there is truly insufficient evidence, the best one can do is to reserve judgment. (Just for the record, I hold out the possibility that there are/were one or more “bigfoot” creatures and possibly even Nessie, but since there is no conclusive evidence for either after all these decades of looking, I lean heavily towards skepticism.)

Hasty generalization

If you recall from Part 4, an inductive argument typically looks at previous, specific examples of X and then makes a general conclusion about X or a prediction about the probability of the next example of X having certain characteristics. In this fallacy, the conclusion is drawn before sufficient evidence has been examined to justify doing so. There might not be enough examples; or, they may not accurately represent the applicable “population”; or, the evidence may not have been adequately analyzed; or,…. Regardless, the idea is that there is not enough good evidence to support the generalized conclusion.

Darth Vader finds lack of logic disturbing“My cousin and his wife are the biggest liberals you could ever meet. I happen to know they have an ‘open marriage’ and promote a hedonistic lifestyle; they insult and get in the face of anyone who disagrees with them; and they support secularist and totalitarian regimes like Cuba and Venezuela. From what I could tell at their recent party, all their friends are, too. (Plus, I see this type all the time in Hollywood!) Obviously, liberals must all be immoral, intolerant communists!”

If I said and truly believed that, I would be guilty of the “hasty generalization” fallacy. Of course, there are some (many?) “liberals” who do fit this description. Fortunately, while I sometimes talk or write in generalizations (as many people do), I know this generalization to be a hasty and unfair one. I think this is also a form of what people call “jumping to conclusions.”

In order to avoid the three preceding fallacies, Prof. Samples’ advice is simply…

LESSON: “Present substantive evidence in support of an argument.”

The next couple of informal logical fallacies show what happens when the words/phrasing used in stating a case is unclear or when it violates the rules of grammar.


Sometimes, a word or two used in an argument can be rather… ambiguous. That is, the word has more than one meaning or connotation, but if one isn’t careful about context, it can be unclear which is meant. This may or may not be intentional, but the result is always an erroneous conclusion.

A prime example of this is when Lawrence Krauss talks about “nothing”. Krauss is a theoretical physicist who writes and speaks on, among other things, A Universe from Nothing. In his efforts to explain a purely naturalistic origin for the universe, he posits some rather odd things. His theories involve energy, gravity, and “empty space” consisting of “virtual particles” bubbling up from a quantum foam. Does that sound like nothing?

At one point, Krauss says,

“If you have particle pairs with a gravitational attraction that is just right for their total energy to be zero, you’re guaranteed that something will arise from nothing. That’s because nothing with total zero energy is unstable and so will create something with total zero energy.”

But, scientists mean different things at different times when talking about “nothing”. When Krauss makes his arguments, he takes advantage of the average layman’s ignorance and that he/she doesn’t realize that Krauss is equivocating between meanings. But, what most people mean by “nothing” when discussing the origin of everything is the absence of everything. When confronted with these challenges, Krauss dismisses them, saying,

“I’m not interested in classical, logical descriptions of nothing, but rather what science tells us about nothing. The philosophical bother may be there, but who cares? … Some of this bothers people. But who cares? Quantum mechanics is illogical -— just get over it.”

Not good enough, Larry. We care! Care to try again?


Yeah, I never heard this term before, either. (For some reason, it makes me think of an Italian dish made of frogs.) It refers to a fallacy that occurs when improper grammar or syntax (or otherwise ambiguous phrasing) causes the reader/listener to reach an incorrect conclusion. Truth be told, I sometimes like to joke around by pretending that I understood something the wrong way, ‘cuz I like wordplay and punnery. Anyway, here are a couple examples of amphiboly:

“Joey claims he likes macaroni & cheese more than his brother. How can he say that about his own flesh & blood?!”

See how that can be confusing? Given a choice, would Joey trade in his brother for M&C? Or, is this a comparison of the relative pleasure the boys get from eating a particular meal? Assuming it’s the latter, it would help to add “does” or “likes it” onto the end of the sentence.

“I like tipping cows with my friends. They really get a kick out of it!”

In this example, the pronoun “they” could be referring to either my friends or the cows. Which is it? You might assume it’s the former, but maybe the cows actually enjoy the game? On the other hand, if the cows lash out at our efforts, it might be my friends who are getting kicked! (That would also be an equivocation of the term “get a kick”.) Of course, occurrences of this fallacy are not always so silly and may be much more subtle. So, beware….

LESSON: “Ensure that the arguments reflect clarity of thought and expression.”

Another five fallacies down! Woohoo!


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