Logic, Philosophy, Reason

A Question of Logic

As everyone knows, it is illogical to say that a proposition is false because of some trait or characteristic of the person espousing the proposition.

For instance, it is illogical to say that “chickens are birds” is a false proposition because the person who said it, Jones, happens to be crazy. Even though it might be true that Jones is crazy, the proposition logically stands or falls on its own merits, rather than the merits of the person espousing it.

Now that’s all very fine and dandy, but that rule applies to formal or deductive logic.  The rules are a bit different in informal or inductive logic.  So, is there ever a time in informal logic when the merits of the person asserting the proposition do indeed become relevant?

Please consider, in informal logic, an argument from authority is logically valid provided that the authority is relevant. If the authority is irrelevant, then an argument from authority becomes illogical or fallacious.

For example, it is usually a valid argument from authority to cite Einstein on the Theory of Relativity, since Einstein was an authority on the subject. But it would most likely be an invalid argument from authority to cite Einstein on the subject of ancient Phoenician blue glassware since Einstein was no authority on the subject. Thus, you can have both valid and invalid arguments from authority.

But, if you can have a valid argument from authority, can you have a valid argument from anti-authority? That is, if you can establish that Jones is more often wrong than right on a particular topic, can you logically cite Jones as an anti-authority?

Example: Jones is wrong most of the time about chickens. Jones says chickens are lizards. Therefore, chickens are most likely not lizards.

Would that be a logically valid argument?

Why or why not?

12 thoughts on “A Question of Logic”

  1. If Einstein is quoted on the subject of ancient Phoenician blue glassware, that Einstein was not considered an authority on it by the opponent in the argument does not necessarily prove that what he said is wrong. And Jones may or may not know a chicken from a church steeple but again, it does not necessarily mean that everything Jones says about chickens is wrong either. Attack the argument, not the person. However it is easier to attack the person (and likely more fun, too).


    1. I completely agree about attacking the argument, not the person. The one exception I would make is if the argument consists in saying that the person’s testimony provides good or sufficient grounds for accepting the argument’s conclusion. Then one might legitimately attack the person’s expertise.

      In formal logic, it is invalid to cite any authority in support of a conclusion since anyone can make a mistake even if they are an authority on a subject. Thus you would no more cite Einstein on the Theory of Relativity than you would cite Einstein on Phoenician glassware.

      But in informal logic, it is valid to cite an authority on a subject so long as the authority’s area of expertise is relevant to your conclusion. Thus, you would cite Einstein on the Theory of Relativity, but not on Phoenician glassware. The key reason is that the odds favor Einstein is right about Relativity, but the odds do not favor Einstein is right about Phoenician glassware. Informal logic is all about odds.


  2. Neither case works, at least for me. People are neither inevitably right. That’s why argument from authority doesn’t work. People are not inevitably wrong, either, even if they’re trying to be.

    To quote the great philosopher Tom Friedman “Just because George Bush thinks something is true doesn’t mean it isn’t.” And yes, I know Friedman was as wrong as Bush about the Iraq situation when he uttered that line in defense of their shared delusion. What makes it a good line is that neither one of them was wrong about everything. They are just really good at being wrong, not perfect.


    1. You’re a hard man, Cujo! Just teasing. I believe I see your point. If so, I think you are taking a deductive or formal approach to the issue. Which, of course, is your right.


  3. I agree with BF and Cujo and would add that in the case of Jones, it seems like you are saying the same thing as you did about Einstein. Jones is not an authority on chickens like Einstein is not an authority on everything outside his field of expertise. Can you argue that when Einstein talks about blue glassware, he is most likely to be incorrect? You might lean that way and be more apt to double-check his statements but I don’t think it’s reliable enough to call logic.


    1. You’re yet another hard man, Alan. All three of you — BF, Cujo, and you — are strict when it comes to logic. I think that’s quite often a good thing. Less risk, fewer mistakes.

      On the other hand, I tend to be more foolish. I like at times to play the odds. As in, what are the odds that Einstein is right about Relativity? What are the odds that Einstein is right about Phoenician glassware?

      Hard cases. My readers are all hard cases. There ain’t a gambling man among ’em.


  4. What about the argument, “When an argument draws much if not all of its force from the intelligence, credibility or integrity of its proponent, his/her intelligence, credibility or integrity are clearly relevant”? Does that provide a compelling grounds for accepting the validity of citing a bona fide anti-authority?


  5. I tend to be a skeptic on most things. Something I’ve learned in my decades on this rock is that I’ve never met anyone who couldn’t teach me something I didn’t know. Wisdom pops up in the damnedest places if a body just listens. It’s humbling if you think about it.


    1. That’s a great point, Kay! It reminds me of something Pema Chodron once said, “If we learn to open our hearts, anyone, including the people who drive us crazy, can be our teacher.”


  6. Does the following demonstrate that it is fallacious to cite someone as an anti-authority?

    “Jones is wrong most of the time about chickens. Jones says chickens are not lizards but chickens are snakes. Therefore, chickens are most likely lizards.”


  7. It is true that the facts asserted stand alone on their own merits. However, what the last question re. Jones does is weigh his credibility into the analysis. Credibility is a factor one should take into account when evaluating the truth of their factual assertions. It is not the only factor, but it is a valid one. The relevant fact that a person lacks credibility because of their track record can certainly be acknowledged and weighed into the analysis without attacking the person.

    For example, consider the boy who cried “Wolf!” Or perhaps a better example: consider Michele Bachmann’s demonstrably ignorant statements about global warming (or just about anything else). As a matter of public record, she is informed by her ignorance and her religious fanaticism. She is not informed by the objective facts. She chooses not to be. Therefore, anything she says, true or not, should be taken with the proverbial massive piece of rock salt. Strike one against Bachmann.


    1. Those are excellent points, CD. I was hoping you would weigh in on this topic because I felt you could shed some light on it with your logical mind, and indeed you have.


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