Is ad hominem ever valid?

[Mobyseven]

Quite correct on all points, but the question wasn't "is ad hominem ever logical?" it was "is ad hominem ever valid?" It is valid, if illogical, in certain circumstances. Flame wars come to mind, you pedantic mongrel taffy-loving... erm... something that is spelled without vowels. Maybe Phllygm.

It depends on what you mean by 'valid' though. Everytime I see the word valid used in this sort of context (discussing arguments, fallacies, etc.), I immediately think of its meaning in formal logic. In that sense, ad hominem is never valid, as it has the form, "P asserts Q; There is something undesirable about P; Therefore not Q."

Having said that, I'd still say that ad hominem arguments are never valid, in any sense of the word - the whole point of an ad hominem is to attack the person asserting the proposition and not the proposition itself. In a situation where it would be reasonable to call into question the character, actions or motives of the person asserting the proposition the argument is no longer ad hominem, instead it turns into an argument with a series of commonly understood, but hidden, premises.

 

[Beerina]

An d hominem as such is never a valid argument. Who delivers a fact has no bearing on the nature of the fact.

But life is not as simple. We can question whether something that is presented in argument is actually a fact. Often arguments depend on the severity of certain effects, and we can question that, too.

In cases like those, a known bias would be a reason to carefully examine someone's claims. But knowing about the bias alone won't be sufficient.

In politics, at least, one should examine the arguer, not just the argument, to see what they might really be up to.

Many times politicians argue one stance, but the real reason is hidden, and deliberately so because it would be considered unwise, if not downright unethical.

Ultimately, though, politics is an evolutionary process, where the narratives (the political streams of thought) become essentially memes that reproduce when they win, and die off when they lose. This has absolutely nothing to do with the truth of the statments, much less their practical effectiveness. (There are no "control groups" to see what would have happened without said governmental law or program.)

The overriding drive is "if it sounds good to the masses", then it reproduces. If a modified, slightly better version by an opponent comes along, then that one wins and the old one starts fading away.

 

[Mister Agenda]

Well, what do you think of this:

in a JREF thread, a certain creationist poster claimed repeatedly that multiple selection pressures "profoundly slow" evolution. Furthermore he claimed to have evidence for that from a computer model. Of course the opposite is true, and (after some fruitless argument) I offered to bet him $10,000, to be settled by the computer model in question. He declined.

I consider that a very effective and valid argument and/or evidence against his position, but I suppose it is technically ad hominem.

Isn't it true that multiple selection pressures CAN slow evolution, or at least act to preserve successful phenotypes when the environment is relatively stable? For example, smaller mice might be selected for during the dry season and larger mice during the wet season, but medium mice are the most common because the selection pressures 'average out'. For one pressure to 'win out' it must become more prevalent or the other pressure less so, otherwise the overall effect is to preserve the status quo.

 

[Nogbad]

Isn't it true that multiple selection pressures CAN slow evolution, or at least act to preserve successful phenotypes when the environment is relatively stable? For example, smaller mice might be selected for during the dry season and larger mice during the wet season, but medium mice are the most common because the selection pressures 'average out'. For one pressure to 'win out' it must become more prevalent or the other pressure less so, otherwise the overall effect is to preserve the status quo.

FFS! don't start that again.

 

[rcronk]

Thanks everyone for your comments. The issue is becoming more clear to me.

Let me give one more example to see if this is an ad hominem or not and if it is logical or appropriate:

Witness X to the WTC 7 collapse claims he heard Jews talking about planting bombs in WTC 7 before the collapse. Witness X runs an anti-Semite website that blames Jews for everything wrong in the world. Therefore X's testimony can be discounted or ignored.

Is that valid logic? Or is this example about evidence gathering and evaluation rather than logic and argument?

 

[Tanstaafl]

Thanks everyone for your comments. The issue is becoming more clear to me.

Let me give one more example to see if this is an ad hominem or not and if it is logical or appropriate:

Witness X to the WTC 7 collapse claims he heard Jews talking about planting bombs in WTC 7 before the collapse. Witness X runs an anti-Semite website that blames Jews for everything wrong in the world. Therefore X's testimony can be discounted or ignored.

Is that valid logic? Or is this example about evidence gathering and evaluation rather than logic and argument?

I think it can be both a reasonable conclusion, and a logical fallacy all at the same time.

 

[Hokulele]

Thanks everyone for your comments. The issue is becoming more clear to me.

Let me give one more example to see if this is an ad hominem or not and if it is logical or appropriate:

Witness X to the WTC 7 collapse claims he heard Jews talking about planting bombs in WTC 7 before the collapse. Witness X runs an anti-Semite website that blames Jews for everything wrong in the world. Therefore X's testimony can be discounted or ignored.

Is that valid logic? Or is this example about evidence gathering and evaluation rather than logic and argument?

I would say that the lack of support for his claim would indicate that it can be discounted but not necessarily ignored. The website could be used as a means to understand why Witness X finds this compelling evidence, but does not affect the evidence itself. Without any corroborating sources, this would fall to the level of anecdote, not evidence.

 

[rcronk]

I think it can be both a reasonable conclusion, and a logical fallacy all at the same time.

Hmm - is it valid in an argument to reject X's testimony? I guess both sides of the argument would have to agree to reject the testimony, which may be unlikely. Is my example in my last post in fact an ad hominem attack? If not, what is it? If so, is it a logical fallacy? Or do we accept all evidence from all sources and not weigh their reliability?

 

[rcronk]

I would say that the lack of support for his claim would indicate that it can be discounted but not necessarily ignored. The website could be used as a means to understand why Witness X finds this compelling evidence, but does not affect the evidence itself. Without any corroborating sources, this would fall to the level of anecdote, not evidence.

Good points. Should his website be ignored completely then? This would basically make his "evidence" have the same weight as a fireman standing next to him with a different story, wouldn't it? Is there any room for the website decreasing the value or weight of the evidence? If so, is that ad hominem?

Thanks all for walking me through this.

 

[Hokulele]

Good points. Should his website be ignored completely then? This would basically make his "evidence" have the same weight as a fireman standing next to him with a different story, wouldn't it? Is there any room for the website decreasing the value or weight of the evidence? If so, is that ad hominem?

Thanks all for walking me through this.

Logically, if the only two pieces of evidence were the testimony of Witness X and a fireman, then they would have the same weight. If the testimony revolved around firefighting techniques, then the fireman's opinion would carry more weight. As mentioned previously, in a court case the question of character would definitely be introduced, and would most likely sway the jury. Appeals to emotion and ad hominems may not be a logical form of argument, but they are often effective. So in that sense, if advertising or politics is your arena, these techniques are valid.

 

[CapelDodger]

Thanks everyone for your comments. The issue is becoming more clear to me.

Let me give one more example to see if this is an ad hominem or not and if it is logical or appropriate:

Witness X to the WTC 7 collapse claims he heard Jews talking about planting bombs in WTC 7 before the collapse. Witness X runs an anti-Semite website that blames Jews for everything wrong in the world. Therefore X's testimony can be discounted or ignored.

Is that valid logic? Or is this example about evidence gathering and evaluation rather than logic and argument?

I see it as a judgement call - evaluation of evidence rather than strict logic. Evidence presented by an irrational witness carries little or no weight. This (hypothetical) witness's rationality is clearly questionable on the basis of better evidence - the existence of his website, which you can check for yourself.

 

[CapelDodger]

An Ad Hominen tends to raise alarm bells within me with regards the strength of the attacker's argument. A strong logical counter to a proposition by another poster requires only a deconstruction of the original statement and indication where there are flaws. A starting point that the OP is a notorious drunk, for example, and therefore cannot possibly be right is clearly illogical - many ad hominems are more subtle than this but they follow the same non sequitur.

After this has been completed one can then proceed to say whether one thinks the OP is a stranger to veracity or, indeed, a complete qunt - but this is an optional extra and should not form part of the main argument which should be able to stand alone.

I have no argument with any of that .

I would just add that when someone resorts to insult before establishing there case, it's good evidence that your argument is getting to them and they can't deal with the fact. It's a sort of "fight or flight" response, and later they'll remember only "well, didn't I put them down!" and forget the disturbing undermining of their conviction.

The best response, I find, is to remain calm and keep pressing your point. That can really drive people wild. I may have learnt that from my mother, who can wield icy politeness as a weapon. (My father taught me how to throw a straight right-jab from the shoulder, with my body behind it. They're both good. )

My mother has a story of her father politely asking a women in a cinema to be quiet. "I've never been so insulted in my life!", she said. "Oh, you must have been", replied my grandfather. Squelch.

 

[JoeEllison]

Thanks everyone for your comments. The issue is becoming more clear to me.

Let me give one more example to see if this is an ad hominem or not and if it is logical or appropriate:

Witness X to the WTC 7 collapse claims he heard Jews talking about planting bombs in WTC 7 before the collapse. Witness X runs an anti-Semite website that blames Jews for everything wrong in the world. Therefore X's testimony can be discounted or ignored.

Is that valid logic? Or is this example about evidence gathering and evaluation rather than logic and argument?

Valid logic? Maybe not in the strictest sense of the word "logic". If you say that his claim is wrong because he is saying it, and then reject it even in the face of supporting evidence, that is a clear logical fallacy. If your thinking is more along the lines of not trusting a source that has proven to be unreliable in the past, that's not so clear cut.

However, from a practical standpoint, it would be very reasonable to confirm that claim through another, less obviously biased source.

 

[CapelDodger]

I would say that the lack of support for his claim would indicate that it can be discounted but not necessarily ignored. The website could be used as a means to understand why Witness X finds this compelling evidence, but does not affect the evidence itself. Without any corroborating sources, this would fall to the level of anecdote, not evidence.

Pushing rcronk's hypothetical way too far, the website gives credence to the possibility that the witness has either invented what he heard (in an effort to get across a message he believes in and regards as of crucial importance); or is irrational enough to have persuaded himself that he heard the conversation when in fact they're an after-the-fact product of his psychosis.

Had he reported the conversation before the fact - and why wouldn't he? He's clearly no slave to political correctness, after all - that would be a somewhat different matter.

The existence of the website is evidence that rises above the anecdotal. He's out and he's proud. Only a fool would ignore that fact.

(The relevance of this discussion to the AGW debate has not escaped me, but I'm not going to go there . Far too contentious. Hypotheticals are much safer ground.)

 

[badnewsBH]

People have already explained this better than I will, but what the heck? I'll give it a go.

I think you commit an ad hominem fallacy if you dismiss a person's argument *solely* on the basis that there's "something wrong" with him. You attack his character, his personality, his parentage, etc., then claim that that's sufficient reason to disbelieve his claims. This is invalid, because a person could be a liar, a hypocrite, a bigot, ad nauseam, and still make a valid point.

OTOH, you can question a person's motives for holding a certain position, and make a counterclaim about the evidence he presents. The thread about our favourite annoying creationist is a good example. His claims aren't incorrect because of any personality flaws he may possess (and I'll leave you to judge how many he may have...), and it would be fallacious to say so. It is, however, perfectly valid to doubt his claims about evolution because he has a clear agenda on the subject, *and* because of the many pieces of evidence that refute his claims (and for which he has no valid answer, only "you evolutionists still don't understand how sorting algorithms and mathematics work").

 

[rcronk]

Ok - so it seems that there's some disagreement about whether witness X having a website that indicates he has a strong bias that is related to his testimony affects the strength of his testimony. Perhaps this is because of the difference between pure logic and people's tendency to try to figure out people's biases as they interact with them. I guess it's ok to think witness X is a nutjob while still considering his testimony and using other testimony and evidence to corroborate or invalidate his testimony.

And hey - feel free to bring in non-hypotheticals into this discussion - even heated ones - because that's where ad hominem comes into play isn't it? In the heat of frustration. It might actually be more instructive to take examples from the forums here since that's where I'll be using this new knowledge.

 

[CapelDodger]

People have already explained this better than I will, but what the heck? I'll give it a go.

Why not? Learn by doing.

Welcome (and great handle) .

I think you commit an ad hominem fallacy if you dismiss a person's argument *solely* on the basis that there's "something wrong" with him. You attack his character, his personality, his parentage, etc., then claim that that's sufficient reason to disbelieve his claims. This is invalid, because a person could be a liar, a hypocrite, a bigot, ad nauseam, and still make a valid point.

OTOH, you can question a person's motives for holding a certain position, and make a counterclaim about the evidence he presents. The thread about our favourite annoying creationist is a good example. His claims aren't incorrect because of any personality flaws he may possess (and I'll leave you to judge how many he may have...) ...

They are legion ...

... and it would be fallacious to say so. It is, however, perfectly valid to doubt his claims about evolution because he has a clear agenda on the subject, *and* because of the many pieces of evidence that refute his claims (and for which he has no valid answer, only "you evolutionists still don't understand how sorting algorithms and mathematics work").

Quite right. The bad-mouthing comes from the k-man (I'm right, yeah?) with his " Your intellectual poverty is the problem", when he's got his head firmly stuffed in a narrow crack that necessarily leaves his ears closed. Were he less obsessed and more sensible he'd have leant over slightly less far and be sucking his own ...

Sorry, rambled off there. Where was I? Oh yes, Welcome, cuz. So far you're with us. Some way up the line ... well, who can tell.

(Watch out for Jimbo, he doesn't load for duck-shooting, know what I mean?)

 

[CapelDodger]

Ok - so it seems that there's some disagreement about whether witness X having a website that indicates he has a strong bias that is related to his testimony affects the strength of his testimony. Perhaps this is because of the difference between pure logic and people's tendency to try to figure out people's biases as they interact with them. I guess it's ok to think witness X is a nutjob while still considering his testimony and using other testimony and evidence to corroborate or invalidate his testimony.

Pure logic can only be applied to definite facts and valid inferences that can be drawn from them - Mobyseven is definitely The Man for that end of things. It applies in science, mathematics, any situations where propositions can have an absolute truth-factor.

What we're mostly faced with in life (let alone the courtroom or politics), is not nearly so clear-cut, of course. Evidence is rarely absolute, it has to be judged.

And hey - feel free to bring in non-hypotheticals into this discussion - even heated ones - because that's where ad hominem comes into play isn't it? In the heat of frustration. It might actually be more instructive to take examples from the forums here since that's where I'll be using this new knowledge.

badnewsBH bit into that apple before I fell to temptation. As long as we don't mention the individual involved by name we probably won't draw him in. Better to talk about him than with him.

 

[Mobyseven]

Thanks everyone for your comments. The issue is becoming more clear to me.

Let me give one more example to see if this is an ad hominem or not and if it is logical or appropriate:

Witness X to the WTC 7 collapse claims he heard Jews talking about planting bombs in WTC 7 before the collapse. Witness X runs an anti-Semite website that blames Jews for everything wrong in the world. Therefore X's testimony can be discounted or ignored.

Is that valid logic? Or is this example about evidence gathering and evaluation rather than logic and argument?

This is what I'm talking about when I say that there can be hidden premises involved when the character of a person is legitimately questioned. To explain what I mean I'll use your idea as an example.

Originally what is said is:

X claims he heard Jews talk about planting bombs in WTC7.
X is a known anti-semite.
Therefore, X's testimony should be ignored.

This seems reasonable on the face of it, but left as it is it is an ad hominem argument. There are a number of hidden premises, however, that are generally understood by the audience. Explicitly stating these can flesh out the argument and show why it isn't ad hominem:

X claims he heard Jews talk about planting bombs in WTC7.
X is a known anti-semite.
If someone is an anti-semite, any claims they make regarding Jews should not be accepted without further corroborating evidence.
There is no evidence that corroborates X's claim.
Therefore, X's testimony should be ignored.

Stated as such it becomes clear that the reason the claim should be ignored is not directly because X is anti-semitic, but instead because there is no evidence to support X's claims. Really, there should be evidence for X's claim regardless of the claim and whether or not he is anti-semitic, but this is the real world and some people are more trustworthy than others.

 

[uruk]

I didn't know where to put a logic/debate/fallacy question so here it is in the "science" section.

I know that in a logical argument, the people bringing the argument to the table should be irrelevant and the argument or position itself should be able to stand on its own. But is there ever a time to question a person's motives or reliability and have that be a part of the argument? I looked at the wikipedia article on ad hominem and it talked about some exceptions being eyewitness reliability, etc. but I'm not sure how that fits (or even if it needs to at all) in a logical debate. Here's a quote from wikipedia:

What if the debate is about the person's motives or reliability?