The Fake, the Flimsy, and the Fallacious: Demarcating Arguments in Real Life

logical fallaciesI recently co-authored a paper — together with Maarten Boudry and Fabio Paglieri — on the topic of so-called “informal” fallacies. These are instances of bad inductive reasoning (as opposed to formal fallacies, which are far fewer in number, and concerning strictly deductive reasoning).

The problem that Maarten, Fabio and I write about is that accusations of informally fallacious reasoning (“ad hominem!”, “red herring!”) are actually too easily hurled around during debates, when in fact many times the alleged fallacy is a pretty reasonable heuristic, or a first approximation at tackling a problem.

For instance, in a court of law, if a defense lawyer points out the notorious unreliability of a witness, technically this is an ad hominem. But in reality it is perfectly reasonable for judge and jury to take into account a given witness’ previous record of reliability before deciding just how much weigh to give to that witness’ current testimony.

Anyway, below is the abstract of the paper, and here is the link to full version:

Philosophers of science have given up on the quest for a silver bullet to put an end to all pseudoscience, as such a neat formal criterion to separate good science from its contenders has proven elusive. In the literature on critical thinking and in some philosophical quarters, however, this search for silver bullets lives on in the taxonomies of fallacies. The attractive idea is to have a handy list of abstract definitions or argumentation schemes, on the basis of which one can identify bad or invalid types of reasoning, abstracting away from the specific content and dialectical context.

Such shortcuts for debunking arguments are tempting, but alas, the promise is hardly if ever fulfilled. Different strands of research on the pragmatics of argumentation, probabilistic reasoning and ecological rationality have shown that almost every known type of fallacy is a close neighbor to sound inferences or acceptable moves in a debate. Nonetheless, the kernel idea of a fallacy as an erroneous type of argument is still retained by most authors.

We outline a destructive dilemma we refer to as the Fallacy Fork: on the one hand, if fallacies are construed as demonstrably invalid form of reasoning, then they have very limited applicability in real life. On the other hand, if our definitions of fallacies are sophisticated enough to capture real-life complexities, they can no longer be held up as an effective tool for discriminating good and bad forms of reasoning. As we bring our schematic “fallacies” in touch with reality, we seem to lose grip on normative questions. Even approaches that do not rely on argumentation schemes to identify fallacies fail to escape the Fallacy Fork, and run up against their own version of it.


17 thoughts on “The Fake, the Flimsy, and the Fallacious: Demarcating Arguments in Real Life

  1. As a newspaper editor, and, along with you, loathe what the mistaken “information is free” idea has brought to “New Media,” I see informal fallacies committed all the time. They’re in bad op-eds, even worse letters to the editor, yet worse online comments to new media, and above all, dumb comments by political candidates.

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  2. Can you please give some more examples of how this fallacies-as-errors approach is incorrect? I can think of many cases in which people who have only a limited understanding of what the fallacies are, or who should know better but are hasty in applying the fallacy labels, go wrong. But you seem to be saying even more: that even at best, this approach leads to problems.

    To seek to discredit a witness in court is _not_ to commit the ad hominem fallacy (though it is to make an ad hominem argument). The ad hominem fallacy only occurs when one attempts to undermine an _argument_ by trying to discredit its source. And that really is always illegitimate. But witnesses aren’t meant to provide arguments in court; only testimony, which the defense and prosecution will then use as a basis for their arguments. It’s long been agreed on all sides, I think, that an ad hominem attack that is meant to undermine testimony rather than an argument is non-fallacious.

    Are there other candidate cases where using a correct charge of fallacy to undermine an argument is illegitimate?

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  3. In the computer programming world we have the concept of a “Code Smell” (c.f. This refers to a bad practice, un-necessary complexity, or various other indications that there *may* be a deeper issue within the computer code being analyzed.

    The important part is that the “smell” is a possible indication of a deeper problem, not a clear indication. I haven’t read the whitepaper yet, but at first glance a possible middle path through the fork is to consider informal fallacies as a *possible* but not certain indicator of a reasoning problem.


  4. Justin:

    You ask:
    “Are there other candidate cases where using a correct charge of fallacy to undermine an argument is illegitimate?”

    If I understand you correctly, another example may be in the incorrect use of the “Argument from authority” fallacy. The misuse occurs when someone actually *is* an authority (or, more generally, an expert) and their input really ought to be considered more heavily than that of a non-expert regarding a particular issue. Climate change deniers and anti-vaxxers often resort to this, for example (they seek to undermine the sources of information, i.e. the scientists and doctors).

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  5. Thanks, Hector. But there again, I don’t think the cases you use are a correct form of the fallacy!

    Even most introductory texts on fallacies (like the one I often use, Bruce Waller’s _Consider the Verdict_ define a fallacious appeal to authority as something like the following: an appeal to authority where either a) the person cited as an authority lacks expertise in the relevant domain; b) there is reason to suspect that the authority is biased in this particular matter (perhaps because he or she has been paid to do an advertisement, etc.); or c) there is no rough consensus among authorities on the issues. In any of these cases, the theory goes, it’s problematic to accept, or try to get others to accept, something as true merely because the supposed authority says it’s true. But this fallacy is _not_ a blanket prohibition on appealing to authorities. The burden is on the fallacy-diagnoser to show that one or more of those cases really does apply.

    So, the climate change deniers and anti-vaxxers are wrong to call the opposing appeals to authority fallacious merely because they’re appeals to authority. That’s just a misunderstanding of what the fallacy entails. And since the consensus of authorities on those subject matters agree that human-caused carbon emissions are harming the environment and that MMR vaccines don’t cause autism, and there’s no plausible reason for thinking those authorities are biased, they’re just mistaken that their interlocutors are relying on a fallacious appeal to authority.

    As in the case of courtroom testimony above, you seem to be attacking an uninformed diagnosis of fallacy at the hands of someone who hasn’t taken the time to learn what the fallacy is. And I agree — but that shouldn’t deter people who correctly understand what the fallacies are from using them to find their way through dialectic, I think.


  6. Justin,

    I don’t think we are that far from each other. First off, my co-authors and I argue that most of the people who cry out “fallacy!” (on both the pseudoscientific and the “skeptical” side) actually do so without a full appreciation of what the fallacy is about.

    Second, however, there is reasonable disagreement about what constitutes an “argument” to begin with, in the informal sense. Simply calling a witness to testify may be an (implicit) part of the prosecution’s argument. When the defense calls into question the credibility of the witness it is thereby (implicitly, again) undermining the prosecution’s “argument.”

    I’d be curious to hear further comments if you have the time to read the paper.


    “at first glance a possible middle path through the fork is to consider informal fallacies as a *possible* but not certain indicator of a reasoning problem.”

    Right, but my co-authors and I argue — while also reviewing the pertinent literature — that there simply isn’t any principled way to classify arguments into informally fallacious or non fallacious ones, that the judgment needs to be made on a case by case basis, depending on what exactly is being argued and how. That is, we think there is no simple classificatory scheme to be had, and no silver bullet to use in argumentation theory.


  7. Then there is the broader observation that reality exists on the edge of instability. The problem with order in and of itself, is that it doesn’t exist distinct from chaos. Definition is reductionism, so the more you isolate the defining features of anything, the more it becomes disconnected from its larger context and the less relevant it becomes. You can’t separate the benefits of ambiguousness from the negatives. So it is a matter of steering and tacking around the argument in question, until the other side drops out, or the evidence precludes further debate.


  8. Yes, Massimo — I’d better read the paper! This is an issue of considerable interest to me, for many reasons: one of which is that, if you’re right, then I’d better change how I present philosophy to my students!

    One more thing, then I’ll wait until I get a chance to read it: yes, I agree with you that testimony can be a part of an argument, and therefore that attacking testimony can be a way of attacking an argument. Here’s a very simplistic example: A tells B that the schoolhouse has burned down. B asks why, and A says

    Premise 1. C claims that the schoolhouse has burned down.

    Conclusion. Therefore, the schoolhouse has burned down.

    Let’s also imagine that B doesn’t find C very trustworthy for some reason. I agree that in this case, A has presented an argument to B, and that B is rejecting the argument because A is rejecting testimony. But the argument contains a hidden premise, as follows:

    Premise 1. C claims that the schoolhouse has burned down.

    [Premise 2: C is reliable.]

    Conclusion: Therefore, the schoolhouse has burned down.

    What B is doing is criticizing the argument in a conventional way — a way that I’m not sure I would call an ‘informal’ fallacy, since B is simply asserting that there seems to be good reason to doubt or reject Premise 2. And then, by what I take to be standard dialectical practice, B has to give A a chance to support the questioned premise (i.e. Premise 2). If A manages to give good reasons for trusting C’s testimony in cases like this, B’s objection fails. If A does not, and B has some good reason for not trusting C that A cannot address, then the objection succeeds. If we imagine that neither A nor B has any reason to believe anything about the schoolhouse having burned down or not other than C’s testimony, then I don’t think anyone would call this discussion about C’s credibility _irrelevant_ to the proper assessment of the argument.

    So the principle stands, I think: If you are attacking testimony, you can legitimately attack the source of that testimony. But if you are attacking an argument, even a testimony-based argument, then you can’t legitimately attack the _source_ of the argument: you have to show either that one or more of the premises is false or dubious, or else that the reasoning that leads from the premises to the conclusion is flawed in some way. And B is doing one of those two things!

    For A to commit the ad hominem _fallacy_ in this case, A would have to attack not C’s character, but B’s, since B is the source of the argument (C is only the source of the testimony, and hence C but not B is fair game in this way).


  9. Justin,

    right, your example — I think — helps make our point. Notice that the premise you add is hidden, which complicates things. One needs to dig out the premise, re-analyze the argument, and then decide whether bad reasoning is involved or not.

    We are not, obviously, saying that people don’t engage in what are often described as informal fallacies. We are simply saying that one cannot just look at a comment and shout “fallacy!,” because it all depends on the details, and these details don’t fall into universal schemata.

    There is actually a fairly large literature on argumentation schemata that is moving away from the notion of informal fallacies. And I, for one, I have stopped teaching them in the usual way to my students!


  10. Hi, Massimo. I’ve now read the paper: thanks for posting it. I remain unconvinced, but I’ll spare your readers a point-by-point response. Hm… maybe I’ll send one to the journal, though!

    I’ll confine myself here to some main points. First, I’m afraid I disagree, as a point of empirical fact, that straightforward instances of fallacies are only to be found in textbooks. Just two days ago, I listened for some time to someone blathering into a microphone on the streetcorner about his religion. He kept telling everyone that they ought to believe in the Bible and be Christians, on the grounds that God had said this, that and the other thing, right there in the Bible. Finally, I caught a moment when he was in a slow bit and said, “Excuse me, but do you really think you’re going to persuade anyone of your conclusion if you just keep appealing to the Bible? I mean, aren’t you trying to persuade people who _don’t already_ accept the Bible as true? And why should those people care what the Bible says? Really, for you to succeed at all, you’re going to have to give them reasons that _don’t_ depend on their trusting what’s in the Bible.” The man turned to me (with his microphone still on) and said, “Oh, you’re saying I should base this on something other than the Bible?” I said, “Yes, exactly.” So he actually gave it a shot, but only lasted about ten or twenty seconds before he was basing his talk on chapter and verse in the scriptures again. Keep in mind that he wasn’t arguing that people should be Christians in such-and-such a way: he was clearly arguing that people should trust the Bible and be Christians. I stood there dumbfounded for another couple of minutes, and then some of his supporters looked at me and one said, “Well, are you convinced now?” I really think that these people were honestly committing a circular argument that was no more sophisticated than any example I’ve seen in a textbook. And I’ve also seen many more educated people who lacked the critical thinking skills to avoid fallacies just as blatant as that one.

    Second, while I agree with you that when Sam Harris, Michael Shermer, etc. shout ‘fallacy!’, it usually isn’t very helpful. But you seem to think the reason is that fallacies can never be cut-and-dried, and I disagree (the story I just told of the street pastor is one example). I think the reason is, first, that Sam Harris, Michael Shermer, and their ilk tend to wildly overestimate their abilities to recognize fallacies, and second, that just shouting ‘fallacy!’ is usually not a very good way to keep the conversation moving. I think it’s better to have the conversation in a different and more constructive way most of the time. But identifying straightforward fallacies as fallacies can be a crucial part of figuring out what’s wrong, I think.

    Third, I think there’s an illegitimate move being made from the premise that some characterizations of fallacies are too simplistic to the conclusion that there are no fallacies that can be easily categorized with a clear set of rules (for a great many cases, at least). To make a comparison with chess: if one side has a bare king and the other side has only a king and knight, then the position is straightforwardly a draw, since checkmate is impossible. That’s a rule that applies no matter what position the three pieces are in. But now suppose that some people who doesn’t really understand that rule claim that a king and knight can’t win against a king and pawn, since the rule says that a king and knight aren’t enough to win. Well, actually, in that position it’s sometimes possible for the side with the knight to win: the rule only applies to cases in which there are only the two kings and a single knight, and nothing else. Does the fact that some people misinterpret the rule and substitute the simpler one ‘If you have a king and knight and nothing else, you can’t win’ entail that there are no good rules like this in chess? Not at all. Good players need to know rules like the actual king and knight vs. king rule: they just have to know it correctly. I think the same thing is going on here.

    And in the case we were discussing, of the schoolhouse burning down or not, I think there _is_ clearly a universal schema that can be easily and correctly applied: I just didn’t explain it very well. The schema is this: it’s never legitimate to reject an argument merely because you have good reason to believe the source of the argument is untrustworthy, but it is sometimes legitimate to reject testimony because you have good reason not to trust the source of that testimony. In most cases, arguments do not involve premises in which the testimony is in question, so the schema is very simple to apply. But there are cases in which the audience doesn’t trust the source of testimony that is crucial to the support for a given premise. In that case, we have the person presenting the argument — call her X — and the person whose testimony supports the questioned premise — call her Y. Following the schema, it’s relevant to raise doubts about Y’s trustworthiness, but not X’s. So there, too, the schema is straightforward to apply. The only other case is when Z presents an argument _and_ is the source of disputed testimony in one of the premises. In that case, Z plays two roles: that of X in the previous case, and that of Y. Following the schema again, it’s relevant for the audience to call Z’s credibility into question insofar as the testimony-dependent premise is concerned, but not insofar as the rest of the argument is concerned (the logic and the premises that don’t depend on Z’s testimony). Moreover, if Z can present independent support for the premise that was otherwise dependent on Z’s testimony, the audience can’t continue the ad hominem attack legitimately. So I think there is a clear schema here that works in all cases! Sorry I didn’t put that clearly before.


  11. Socratic,

    my colleagues and I are suggesting that we should do away with informal fallacy talk because it isn’t very useful, and replace it instead with a more articulate case-by-case analysis of why, exactly, a particular instance of reasoning is bad and where it goes astray. Yeah, not very appealing because there is no one-size-fits-all solution, but we think it’s more realistic and, in the end, more useful.


    I hear you and I appreciate your feedback, but even your case of the street preacher isn’t really good enough, I think. Suppose I tell you that quantum mechanics is real because I’ve read it in a book on quantum mechanics. This may not be a good reason, but it’s good enough for the purposes of a conversation between you and me, assuming neither of us knows much on quantum mechanics and you just made a Deepak Chopra-style assertion about it. My invocation of an independent authority is circular, but also justified. The preacher may argue along similar lines, pointing to other reasons why there is a God who inspired the Bible. (He didn’t, but that’s just his own lack of sophistication in argumentative discourse.)

    Think of what we are proposing as analogous (in a way) to why Popper’s falsification doesn’t work: in that case it’s the Duhem thesis, which says that every time you run an experiment you ar not just testing the focal hypothesis, but also a number of often unstated and hidden ancillary ones. Similarly here: one shouts “fallacy!” (there is even an internet site about “your fallacy is…”) and that becomes a shortcut for an actual, engaged analysis of whatever it is that is under discussion.

    “it’s never legitimate to reject an argument merely because you have good reason to believe the source of the argument is untrustworthy”

    I disagree. It is *often* legitimate as a heuristic: I reject anything that Deepak Chopra says, as a first approximation, on the ground that he is a notorious quack and I don’t have time to stop and analyze in detail every single instance of what he says.


  12. Fallacies, it seems, happen primarily in textbooks (Finocchiaro 1981).

    They(fallacy accusations) also happen on secularist internet discussions where they serve the roles of jargon, sloganeering and polemical rhetoric. Their main purpose seems to be to cultivate and demonstrate feelings of superiority and membership of an in-group.

    They have the great advantage(for the dishonest) of delivering a blow in a quick, pithy phrase that need not have much relationship to the facts of the matter. They are the argumentative equivalent of a drive by shooting.

    it’s never legitimate to reject an argument merely because you have good reason to believe the source of the argument is untrustworthy — I disagree. It is *often* legitimate as a heuristic

    It is a most dangerous heuristic and should be avoided(even though I agree with you about Deepak Chopra). It is a weapon most often used to smear, reinforce and propagate bias and prejudice. For example Dennett imputed that Alfred Meler’s recent book about free will was unreliable because he had accepted Templeton funding. He could not fault Meler’s reasoning so he resorted to this shabby smear technique. Dennett’s behaviour was downright distasteful.


  13. labnut,

    I agree that the use of heuristics has its own pitfalls, and I certainly agree that people — including skeptics — have started using the “it’s a fallacy!” cry as a quick way to deal what they think is a fatal blow to their opponent. That, in fact, is what motivated Maarten, Fabio and myself to write the paper to begin with. But:

    “For example Dennett imputed that Alfred Meler’s recent book about free will was unreliable because he had accepted Templeton funding”

    I think I’m honestly on much more secure territory than Dennett when I reject Chopra without (further) argument.

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  14. I think I’m honestly on much more secure territory than Dennett when I reject Chopra without (further) argument.

    Oh yes, for sure. So let me reconsider my opposition to an argument because its source is considered untrustworthy. More nuance is called for. If it is a simple argument we should usually consider it on its own merits. If it is a very complex and detailed argument we must place some trust in the source of the argument.

    It is a little like a court weighing the testimony of an expert witness. A court cannot verify the expert witness’ assertions and so must place trust in the expert witness. Trust is granted when the following questions can be answered positively:
    1. Does he have the relevant expertise?
    2. Does the testimony have relevance?
    3. Does the testimony have probative value?
    4. Is there evidence of bias or wishful thinking(is this a reliable witness)?
    5. Does the witness have good standing in his profession?
    6. Does the evidence survive testing against the testimony of other expert witnesses?

    Finally we make a judgement on a balance of probabilities. Is the conclusion plausible?

    We seldom break out our judgements in this explicit way. Mostly we intuitively apply the above tests and reach a conclusion about the person’s plausibility.

    For a great number of judgements in life we are like the court that depends on the testimony of expert witnesses. Mostly we are pretty good at intuitively applying the above tests and reaching a balance of probability judgement of the source’s plausibility.

    Plausibility exists on a continuum and when we apply the tests to Chopra he is a strongly implausible witness so we are entitled to prima facie discount his evidence.

    So whether we discount a witness or examine his arguments on their merit depends of two things:
    1) can the arguments themselves be reasonably be examined and tested?
    if not
    2) is the evidence of the witness plausible, as measured by the above tests?

    Finally we can conclude that the more implausible a witness is the less effort we will devote to examining his arguments.


  15. I must admit to getting a little help from Douglas Walton’s two books:
    1) Fundamentals of Critical Argumentation
    2) Legal Argumentation and Evidence

    Legal practice is a terrific guide to good argumentation.


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