Tuesday, July 24, 2012

Logic Lessons pt 6: Fallacies of Argumentation

Fallacies of Argumentation
These are fallacies that are very similar to something we shall look at later: formal fallacies
In these, there is a problem inherent in the truth of the argument.

  1. Non sequitur = “it does not follow.” Conclusion does not follow from premises and evidence. This is inside any invalid argument but it is a material fallacy. Note the following example:
    a. The sky is gray
        b. I am angry
        c. Therefore, the sky is making me angry.
        The above example is a Non sequitur, because premise a and b are completely unrelated and you cannot draw a valid conclusion from it. It is different that a formal fallacy, like so:
        a. Sky is Blue
        b. Sea is Blue
        c. Therefore Sky is Sea
Here, the two premises are related, but the conclusion is incorrect because of some problem with the logical form (more on this later).

Non-sequiturs are often used when people are need to make an emotionally charged argument with little data. Putting the 2 concepts in proximity gives the illusion of a conclusion. I remember I was talking with someone who asked my what I thought about the newly elected Pope Benedict XVI. I said I loved him and thought he was great. This person was disgusted and responded, “What about AIDS?” I was a little taken aback and said, “Um... I think it's bad.”
The argument as presented informally to me by this person was:
a. AIDS is bad
b. Pope got elected
c. Therefore, Pope wants to spread AIDS.
(to be fair, her argument was a little more sophisticated than that if you factor in 2 hidden assumptions. But as it was presented, this was the argument). Notice how similar a non-sequitur can be to a fallacy of diversion. The main problem for a non-sequitur is that it is missing something called a “middle term.” (more on this later)

  1. Ignoratio elenchi = “ignorance of the claim” or “irrelevant conclusion.” This is giving reasons that prove a different conclusion than what you claim. For example, imagine this dialogue (example taken from Dr. Peter Kreeft):
    Neville Chamberlin: “Peace is preferable to war. Do you agree?”
    British People: “Yes.”
    Neville Chamberlin: “Therefore let us appease Hitler, because not doing so would lead to war.”)

  1. Begging the Question = assuming what you set out to prove. In the movie Legal Eagles, a defense attorney played by Robert Redford seems to snap in court and tells the jury to convict his client. When A juror says that she deserves a fair trial, Redford says, “Okay, we'll give her a fair trial. And then convict her.” Obviously, she cannot have a fair trial if the conclusion is set. One of the most important things Socrates taught us was to follow an argument where it goes and not to try to force a conclusion that did not follow the evidence.
  1. Complex Question–asking a question which cannot be answered without begging another question. For example, there is the classic: “Yes or no: Have you stopped beating your wife?” Of course a yes answer implies that you did beat your wife at some point. A no answer means that you still are beating her. The question that should have been asked first is: “Have you ever beaten your wife?” Another example is the question, “Who made God?” There is a hidden assumption here that everything that exists has a beginning.

  1. Arguing in a Circle = using a conclusion to justify a premise after using the premise to justify the conclusion. Unfortunately these arguments are often used when talking about religion. A dialogue may go like this:
    Unbeliever: How do you know God exists?
    Believer: The Bible says so.
    Unbeliever: Why do you believe the Bible is telling the truth?
    Believer: Because God wrote it.

This also happens from the other side of the belief spectrum
Unbeliever: There are no miracles
Believer: But people witnessed them.
Unbeliever: Those people are liars
Believer: Why?
Unbeliever: Because there are no miracles.

  1. Contradictory Premises: When there is an obvious contradiction in your statement. (e.g.“I will not tolerate intolerance.”
  2. False Assumption: This is the basis of all jokes. Once again to take an example from Peter Kreeft:
    A mailman on his daily round was confronted by a large, ferocious dog in front of a house. An old man sat on the front porch.
"Hey," yelled the mailman, "Does your dog bite?"
"No, he doesn't." said the old man.
The mailman proceeded to move toward the house, and the dog immediately bit him on the leg! After fighting the dog off with his mailbag, the mailman proceeded to the house, keeping a watchful eye on the dog. After straightening his mailbag, he handed the old man his mail.
"I thought you said your dog doesn't bite!" he sneered at the old man as he pulled up his pants leg, revealing a large bite mark.
"That's right. He doesn't bite." said the old man calmly.... "That's not my dog!"

1 comment:

  1. Your post is a nice reminder that logical argument is NOT the sole property of atheists. We do best to keep our wits sharp.
    That dog joke is just silly and worthwhile, hee hee.