Fallacies and Argument

The Informal Fallacies:

Here is an article called On the Fallacy of Proclaiming Fallacies. H/t to the Normblog. I don't read the Normblog as often as I should, but it's on the sidebar (under Eric's Favorites), and once in a while I remember to click through. Today he's talking about the misuse of logic in argument. He's making a point that I was just making ref: gay marriage over at Winds of Change.

Normblog says:

For my own part, I have no idea whether charges of fallacious reasoning are more commonly on target or not on target. I wouldn't know how to start quantifying it. But, to focus merely on this one example, there's a simple and basic point. Sometimes it's appropriate, and involves no fallacy, to point to the personal interests of an opponent in argument; and other times it isn't appropriate and is fallacious.
We can go further than "sometimes." There's a particular quality that makes an argument a fallacy: it is when you are using that argument as the guarantor of the truth of a logical claim.

Here are two uses, one fallacious, and one not.


"Senator X has a conflict of interest, and therefore should not be trusted on this issue."

Not a fallacy:

"Senator X has a conflict of interest in this matter. Further, she does not appear to have accounted for it in public. Finally, the unspoken interest appears to drive her in the direction of the policy she is proposing. Therefore, we should not trust her on this issue."

The first is a fallacy because it is an error in logic. "An error in logic" is, actually, what the word fallacy means. The fact that a conflict of interest may exist does not entail that someone cannot be trusted. A given person may have that conflict, be honest about it with themselves and with you, and do his or her best to ensure a just and fair conclusion.

However, it's perfectly fair to mention the fact of the conflict as part of a chain of reasoning. It's only a fallacy if you are using it fallaciously: as if it were sufficient to entail your conclusion, when the fact by itself is not.

It's possible for both sides to misuse fallacies: "Robert Byrd is a former Klansman, and therefore we should not listen to him on this [unrelated] subject" is a logical error because it is a fallacy (argumentum ad hominem). It is being used as if it entailed a conclusion that it does not.

"Any attempt to mention Byrd's past with the Klan is to be dismissed as a fallacy," however, is a more serious error in logic. It is a category error, one of the most serious types of logical errors. In this case, you are putting any mention of a true-but-negative fact about someone into the category of "things not to be considered." You can see why this is a serious error: it leaves you in the position of believing that you simply may not consider issues of character when making decisions. All negative information about a man's character ends up placed in the category of "inadmissible evidence." Logic does not suggest that to be a wise course, let alone a necessary one.

At WoC, the alleged fallacy was 'argumentum ad antiquitatem,' the appeal to tradition. It's a fallacy to say, "We have always done it this way, so we should do it this way." It's not a fallacy to point out the facts of history, however; and any category building that dismisses tradition and history as possible sources for information on future decisions is a serious error indeed. Logic is meant to be a torch, not a blindfold.

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