Thursday, May 01, 2008

Logical Fallacies

When I was in high school I read a book* about the culture of debate in ancient Greek, how much attention they paid to avoiding logical fallacies, how they would point out each other's mistakes. Sitting among groups of teenagers who'd shout each other down over all kinds of nonsense I sometimes urgently wished this would have been part of our curriculum. That wish persisted when ten years later I was sitting in physics seminars. The difference to the shouting teenagers was marginal. But it has always been a pleasure to talk to mathematicians who were usually precise with their argumentation, didn't take it personal, and knew what a conclusion is. Yeah, possibly the sample of people I know isn't representative neither for physics nor for math, but to me mathematicians became more or less the defenders of our culture.

Anyway, now that I've become a blogger, you might have noticed that I have occasionally done little more than pointing out a conclusion doesn't apply for there was a mistake in the argument. Now interestingly recently we've had some commenters doing the same. That will surely teach me to write more careful :-) I also recently came across this article at SciAm blogs

and The Skeptics Guide To the Universe (your escape to reality) who offers a list of logical fallacies that is brief but understandable and covers what one needs to know.

A more detailed list is here

As is says very nicely on this website pointing out a logical fallacy is a way of removing an argument from the debate. And seriously, in times were people echo back and forth the same issue through Web 2.0 until it's completely blown up and out of proportion, I think this would occasionally be very useful.

One of the logical fallacies that is somewhat wider known is the argumentum ad hominem, which points out that an argument does not address the issue itself but rather the person who made it. This does not necessarily have to be an insult. For example, one of the commonly used attempts of 'critical' thinking one finds in the media is pointing out the person making a statement is likely biased, thus shouldn't be trusted and his/her argument be discarded. Though I agree that in case somebody is likely to be biased (because of employment, funding, personal experiences etc) one should be very cautious, this doesn't mean one can simply dismiss the argument (and its conclusion, survey results, recommendation, advice) for that reason. This too is an argumentum ad hominem.

So, if you know some article or blog post that makes a good example for a logical fallacy, let me know! (Of course that would mean said article has some content and conclusions to begin with.)

* Sorry, I absolutely can't recall a title or author, but it wasn't a really good book anyhow.


  1. Hi Bee,

    Do you know this page?


  2. I've seen plenty use the "Argument from authority" on various blogs and comments.

  3. Logical fallacies are singularly one of the most important and one of the most confusing things I have attempted to apply to real life situations. Each time I think about things with these in mind, I generally make things clearer to myself.

  4. Dear Bee,

    thanks for the pointer - the "straw man" and "weak man" are ideed used quite often. And I wasn't aware that any argumentation involving the person presenting a point counts as "ad hominem". But then, taking into account who is making a certain argument can be quite important for a critical evaluation - and I think the same holds for the "from authority" technique.

    I mean, that these rhetoric strategies are used does not necessarily imply that the arguments they try to push are flawed?

    Best, Stefan

  5. Dear Stefan,

    It's not generally a 'problem' involving the person presenting it, just if you use it for the argument if it isn't of relevance. In some cases this might be relevant. E.g. many people like to argue with personal experience, which shouldn't be dismissed. Like, if you claim 'Nobody does X' and somebody says 'Well, I do!', that's certainly an argument ;-) An example for what I meant to say you have seen in the previous post, that is the argument the risk estimate for CERN is doubtful because of the people who did it. This argument doesn't actually address the point (namely whether the risk has been underestimated), but only the people who presented their conclusions. It is thus not an argument that is good for anything. It is true that for many purposes it is advantageous to assure people in some committee are as unbiased as possible because otherwise they might share misconceptions or be tempted to argue from a one-sided point of view. But this doesn't necessarily have to be the case, and is certainly not a reason to dismiss the conclusion.

    One also has to say that in very many instances the reliability of the person providing an information is an important factor to judge on it quickly. Like, you are probably more inclined to listen to the paramedic than to a random guy on the street.

    As Rae Ann also says, the 'argument from authority' is for this reason very wide spread, and it is the most frequent argumentation used in newspapers. Look at all the science articles, e.g. the recent one in the NYT about the black holes at LHC. They make their argument with quoting well known people in the field. I'm not saying this is an entirely bad thing, as it probably is very efficient in making a point, but it doesn't actually provide any insights and doesn't allow the reader to follow a conclusion. Best,


  6. I thought of the movie, The Great Debators.

    This has given me some food for thought, as well contributing to some incubation in regards to "rhetoric of the ancient ones."

    This goes to the idea of what is self evident, and what induction/deduction plays in that exchange? Where one would like it to go?

    An "intuitive space" that leads to other ideas and exchanges that produce further possibilities to consider. Like, "ingenuity to perform" perhaps? This brings one back to the use of the Whiteboard and the group collaboration.

    Philramble's comment,"Logical fallacies are singularly one of the most important and one of the most confusing things I have attempted to apply to real life situations," would seem a difficult one as well just in terms of remembering all the facets of the execution and awareness of what one is doing.

  7. I do not dare point fingers anywhere to show areas where I think aspects of this were to be considered.:)

    But some of you would know that by a certain ideals toward censorship, such opinions would not be highly regarded if I said them myself:) So what logic is being used to make my point?

    Here are some pointers that one might like to consider in the greater context of debates amongst the different blogs, and those who hold a "special view" too, one side or the other?

    Lee Smolin:

    -Stick to the issues raised. If someone raises a criticism, whether its done according to your standards of rhetoric or not, just answer the substantial science issue. Don’t waste our time with discussion about anything else. Don’t respond to a criticism on a specific point by changing the subject.

    -No personal attacks, absolutely none. If someone has a Ph.D., then they are credentialed. Discuss with them in good faith and with respect.

    -Let’s strive to agree on facts before discussing interpretation. Insist on precision and honesty, don’t allow exaggeration, and admit it gracefully when you are wrong or when the evidence does not support something you would like to be true. If someone questions the status of a claim, don’t say “everyone I respect believes X is true.” Say, X is in fact unproven, but there is evidence for it, which is exactly the following….

    -Listen carefully to those professional colleagues who read the evidence differently from you, and try to understand sympathetically and in good faith, why they do so.

    -Restrain your own communities. Make it clear that it is not acceptable to you when those in your committee insult others or publish or post things that are exaggerated or false. If someone insists on behaving badly, it is up to their community to restrain them. Make it clear that repeatedly treating colleagues disrespectfully in a public forum amounts to professional misconduct. The same is true for repeated cases of knowingly exaggerated or misleading statements in a public forum.

    If we can all agree to some basic rules like this I am optimistic that we-and science- will come out better from the debates ahead.

    Progression is Made?

    The points about Mandelstam and genus figures in relation.We were all really quite enlightened when drawn to the limitations written in a book, have now be expanded.

    So who's perfect?

  8. This belongs here also:

    Always remember that a fallacious argument doesn't have to lead to false conclusions. (Thinking it does might be called "the fallacy in reverse.") It is just unreliable, such that if true, it is a lucky coincidence. For example, consider a dog thinking: "I have four legs, dogs have four legs, therefore I am a dog." Well, he got it right that time, but a cat using the same fallacy of converted conditional would end up wrong.

  9. Since "logic" underpins a much bigger ensemble of systems than its usage in common language usually assumes, so does Logical fallacy.

    Logical fallacy usually refers to a fallacy within propositional logic.
    Fair enough, but there is more to the world than propositional logic. If there wasn't, theoretical physicists would be out of businness.

    Usually, "poisoning the well" and "ad hominem" arguments work pretty well,
    _provided that_ the "ad hominem" itself is based on good evidence.

    It is a fact that nearly every scientific study since the 60s which claimed that there is no link between smoking and cancer was funded by tobacco companies.
    Pointing this out to invalidate the study is a "logical fallacy", but to be honest its also a quite convincing argument, first and foremost if you believe certain things about the scientific method.


  10. It was the 2004 U.S. Presidential election that raised the straw man argument into my consciousness. I noticed the preface "some people say" on one TV network in particular - enough times to wonder "who are these 'some people' that 'say' (x)?"

    It's been interesting to me ever since!


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