How Not to Argue Like an Idiot…The 15 Most Common Logical Fallacies

Whether we like it or not, the protestant tradition is founded on “reason and the scriptures” – whether it’s Martin Luther standing before the Diet of Worms, C.S. Lewis apologetically defending the faith via radio waves, or Jonathon Edwards detailing the philosophical argument for the captivity of the soul – we are a community founded on the ability to reason. But I’ve used and heard plenty of bad reasoning from Christians. The following list is composed of some of the most common logical fallacies; I’ve chosen to limit it to only those I’ve actually heard in the last couple years.

Warning: I think logical fallacies have limited value; citing logic as the ultimate end-all of argumentation is itself a logical fallacy – it is a circular argument (I believe logic is authoritative because that’s logical) and it’s an appeal to authority (logic). That doesn’t mean, however, that’s its useless! Logic is a good tool, just not an authoritative tool.

Either way, whether you write or preach, communicator beware:

1. Ad Hominem – Attacking someone’s character rather than their argument. I was sitting with my friend a few weeks ago, debating the significance of a Greek word when he blurted out: “Well, they all translate it that way because theologians want people to go to hell!”

2. Straw Man. This essentially comes down to stating the argument of your opponent in a way they themselves wouldn’t have said it. I’ve heard countless sermons in hyper-conservative circles portraying non-Christians saying things I’ve never personally heard a non-Christian say.

3. False Analogy. In our age of creativity, this is probably the most common – how many times have I heard a debate “settled” because one person uses a beautiful analogy to illustrate their point? All analogies break down at some point; we need to know when and how in order to analyze them.

4. Slippery Slope. The argument that the extreme of a position must be true as well. I heard a Catholic radio DJ say that if we didn’t take the “body and blood” of Christ literally, we’d have to throw out his deity and the gospel itself as well. Or we might say, “If we allow homosexuals to marry, we must allow humans to marry dogs and cats and multiple partners, etc.” This is a different argument than the lesser to greater argument (by the very same principle, this also must be true) – sometimes it’s hard to tell the difference.

5. Confusion equals Cause. This argues that because we don’t understand something, God must be the solution. Because science can’t explain ______, God must be responsible.

6. Argument from Authority.  I need to be careful here, because I believe ultimately, all of us argue from authority – whether it’s the authority of logic, experience, emotions, tradition, or the Bible. But still, we are to avoid arguments purely from authority; I must have a reason why I believe my authority is authoritative! Maybe a better way to say it is: “Argument from human authority”. After all, if our premise that God is omniscient and omnipotent is accurate, He doesn’t need to give us premises. That’s the whole point of the book of Job. We would do well to recognize as well that the reformation debate was over whether humans could claim Divine authority, with the assumption that Divine authority dictates truth.

7. Correlation equals Causation. Assuming that because two things happened simultaneously, one caused the other. For example, I’ve heard professionals say that listening to classical music increases intelligence, because studies done indicate there’s a correlation between the two. Later on, we found out this was bogus, considering all the other factors (for example, those who listen to classical music generally come from elitist cultures, generally indicating wealth, which means the family can afford better education).

8. Psychologist’s fallacy. Assuming that we are an unbiased audience. For example, citing our personal reading of scripture as the objective reading, and everyone else’s as “human opinion”.

9. False Dilemma. Giving two extremes as the only alternatives to a position, when really there are multiple positions: “Aka: If you don’t believe hell is eternal for everyone, you’re a universalist.” I fell into this one today when I cited my reasons I think guys should embrace singleness instead of waste their time dating. My friend corrected me by noting that his modified experience of dating allowed both he and his fiance to continue to take advantage of their singleness.

10. Moral Equivalence. Citing one complex moral event as being identical to another: “Abortion is just like the holocaust”

11. Meaningless Question: Assuming that all questions are logical, aka: “Can God create a rock so big he can’t lift it?” That’s like asking, “Can God create a lakjnsdfnj?” The question itself is illogical. God can do the impossible, but he cannot do anything illogical. I recently had someone ask me a meaningless question about my interpretation of a text, to which I replied, “What if I asked you the same question about a different verse of the Bible?” The question was the problem, not my befuddled inability to answer!

12. Argument from consequence. Because we don’t like the consequence, the argument must be false: “If we believe in the gift of prophecy today, then anyone can claim to speak God’s word.”

13. Red Herring. Continually changing the argument, rather than following it to its conclusion. AKA  – when I asked a blogger why Jesus claimed to be God, he cited a whole host of other biblical passages about God being “one”.

14. Begging the Question. Assuming your premises, rather than explaining them. “Killing animals is wrong because it’s just plain gross!” or “Homosexuality is wrong because it’s disgusting!” These aren’t arguments – they’re begging the question.

15. Appeal to ignorance. “You can’t prove God doesn’t exist; therefore He does.” Once again, this is slightly different than saying: “scientific evidence doesn’t apply to metaphysical realities” – no one can prove scientifically for or against the existence of God, so both scientific sides of the argument are irrelevant.

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37 Comments

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  • http://timfall.wordpress.com/ Tim

    Is number 7 the same as post hoc ergo propter hoc? That one always gets me, especially because when I try to point out to the person that they need more than chronology to prove most things, they look at me as if I have two heads.

    On number 9, I just read that earlier today. A thoroughly complementarian blogger was detailing some of the problems with the biblical patriarchy movement, quoting passages and addressing the issues in them. One point she didn’t address from an excerpt was their statement that egalitarian doctrine necessarily leads to matriarchy. What malarkey they spout.

    Nice job getting us thinking better. Once again I leave your blog smartified.

    • nmcdonal

      That’s a good question on number 7, Tim – my instinct is that there is a nuance of difference, but I’m not totally sure on that one. Actually, I almost asked you to write this article for me, since I’m sure you filter through a lot of these things in court. I’d still love to have you write a follow up, purely due to my own fascination.

      • http://timfall.wordpress.com/ Tim

        Fascination? A lot of people look at me and murmur the word “fascinating”, typically in a Spock-like manner. I don’t think it’s complimentary …

  • Adriana

    One thing is certain: I’d rather not argue with either of you! :)

    Honestly, I’d like read a post on each of these logical fallacies.There is a lot here. It would be helpful to see them fleshed out with more examples. (And that’s not a criticism of you, Nick. This is a long post.)

    I’ve heard them all at one time or another. And a few, esp. the “straw man” many times. I was brought up ultra-conservative, so I’m still working through everything I’ve taken in through the years. I’m try to “eat the fish; spit out the bones.” as I slowly work my way through issues.

    I think I have become much less argumentative than I once was. Maybe that’s because the more I learn, the more I realize what I don’t know!

    • nmcdonal

      As the good old Dale Carnegie has said, the only way to win an argument is to avoid one! I think arguing less is a good thing – I’m much more interested in thinking through our opininons carefully. Good insight, Adriana.

      • Adriana

        I once took a hard stand on some things which I now view differently. I was very outspoken about them. I must have been convincing b/c a friend of mine made some major life decisions due to my influence on her. When I started to see things differently, I lost her friendship. It was excruciating for both of us.

  • http://prinsenhouse.blogspot.ca/ Jeannie

    I enjoyed this very much! I teach an online course in essay-writing and we have an assignment on critical reading which deals with all these kinds of fallacies. Another good one is “the argument from absence” — e.g. “Jesus never praised iPods, so He must not be in favour of them,” or its flip side, “Jesus never said iPods were bad, so He must like them.”

    I always thought an ad hominem attack usually meant referring to someone’s (supposed) bad points, but something I read recently made me realize it can also mean attacking someone’s advantages: e.g. “His viewpoint on this issue is useless because his parents were millionaires and he went to a plushy private school.” Just hadn’t thought of that before. I agree with Adriana — always something to learn!

    • nmcdonal

      Ooooh, I want to take that class! I was first exposed to these fallacies in high-school while taking a “logic” course, and I was fascinated. Is there a subtle difference between the argument from absence and the argument from ignorance? Fascinating point about the reverse ad-hominem…I think may even see that just as often!

      • http://prinsenhouse.blogspot.ca/ Jeannie

        Re the absence/ignorance thing … I think they are v. similar but not identical. Actually maybe the one I was referring to occurs most often when someone’s trying to appeal to authority (which is another of the examples you used!) — i.e. when the person’s trying to show that whether something’s important/right/wrong depends only on whether their esteemed/vilified authority figure does/doesn’t mention it. “The Pope’s speech didn’t mention the abuse scandal, so that means we should put the issue aside and move on.” OR “The Pope’s speech didn’t mention the abuse scandal, so obviously the entire Catholic Church is 100% unconcerned with the issue.”

        Other names for this fallacy would, I suppose, be “You can’t win for losing” or “Damned if you do, damned if you don’t” ……..

      • nmcdonal

        Good one, Jeannie. Kind of reminds of the the “no true Scotsman” fallacy – we give something a characteristic (all scotsman are intelligent presbyterians), and someone points something to the contrary so we say, “Well, he’s no true scotsman!” You can’t win for losing!

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  • CLA

    I saw this statement on a secular website, ” Correlation is not causation but correlation is suggestive”. Does correlation suggest where we might seek causation?

    • nmcdonal

      I think that’s a good point, CLA. Correlation should make us say, “Hmm…”, but not “Aha!”

      • Adriana

        I like that. :)

  • Liz W

    One of the more annoying things I see, on the other side of the logical fallacies, is people cutting off an argument with which they disagree with “correlation is not causation”. Of course some of these same social scientists will make arguments from correlations in their own research (with appropriate interpretive cautions and calls for additional research), but bring up a finding that they don’t like (say, that people who live together before marriage are more likely to divorce, or children are better off with a mother and a father) and suddenly it’s “well, correlation is not causation”, as though that settles the whole thing. Arg!

    • nmcdonal

      Well, Liz, next time you hear that, you can interrupt and inform them that they are actually commiting a logical fallacy: it’s called the “logical fallacy fallacy”, which states that if a poor argument is made for a conclusion, the conclusion isn’t true!

      • http://stephanstrategy.wordpress.com stephanstrategy

        Good to note. Just because an argument may have a fallacy does not mean that the premises or conclusion is false.

      • nmcdonal

        Exactly, Stephan.

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  • http://nathanmillican.wordpress.com nathanmillican

    This was really helpful, in particular just simply defining them. Thanks!

    • nmcdonal

      Glad you benefited, Nathan.

  • Bill

    If you had two heads instead of one, you could post more hoc then get yer gun. You could set them up and knock the down. You could grin all day and never frown. Unless of course you get too close to the slippery side of the sliddery slope. If you think this rhyme a bit confusing, then it just might fail to be amusing. One opinion could set two free unless both heads would disagree. Left to right could be your guide. Right to left could cause false pride. Cause left is loose and right is tight. And when I twist with all my might, it just won’t budge unless I’m turning, the way it goes… Just takes some learning. Besides this rhyme that don’t mean squat, how many fallacies have I got?

    • http://prinsenhouse.blogspot.ca/ Jeannie

      I want what he’s having.

      • nmcdonal

        Yeah, boy.

      • Bill

        Confounding Variables, if not identified, cause bias, and could even subvert justice. “If Supreme Court makes marriage, as it has been known since the creation of man and woman, unconstitutional, then only outlaws will have inlaws.”

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  • Edward Webber

    “I must have a reason why I believe my authority is authoritative! Maybe a better way to say it is: “Argument from human authority”. After all, if our premise that God is omniscient and omnipotent is accurate, He doesn’t need to give us premises. ”

    And here we have what is called Special Pleading, another fallacy. Everything is wrong except what i want to be true. Everything needs evidence except my claim. Arguments from authority are baseless except when i say so.

    As for the logic being a circular argument, you made a circular argument, but you making a bad argument does not make logic circular. That is an argument from incredulity, another fallacy. Logic is used because it has a prefect track record in making predictions. Using logic to make a prediction will always lead to the same conclusion. It is the most reliable means of objective conclusion anyone had devised.

    To claim logical fallacies are not very important is to say blind guessing is equal to evidence based prediction. Logic ensures everyone comes to the same conclusion based on the same premise. Fallacies are where rational thought goes to die.

    • nmcdonal

      I’m aware of Special Pleading, and I think you’re misunderstanding why “Special Pleading” is a logical fallacy. Also, it’s impossible to claim that logic has always made perfect predictions – you’d have to be omniscient to make that claim, so yours is an appeal to your personal experience, which I do not accept as authoritative.

      • Edward Webber

        “I’m aware of Special Pleading, and I think you’re misunderstanding why “Special Pleading” is a logical fallacy.”

        You’re welcome to think that, but you’d be wrong. Special pleading is a fallacy when you hold everything except your claim to a certain standard of evidence, which is precisely what you do when you claim everything requires a premise except your chosen deity. That is a perfect example of special pleading, and one I use in my logical fallacies lectures on a regular basis.

        “Also, it’s impossible to claim that logic has always made perfect predictions – you’d have to be omniscient to make that claim, so yours is an appeal to your personal experience, which I do not accept as authoritative.”

        And you fall for your own fallacy example, thinking because an argument is not proven right in front of you, at that very moment, it is wrong. In fact, logic is the only known method of making predictions and is instrumental in all of science. Without logic, blind guessing is all we would have, as using evidence, rational thought, skepticism, mathematics, physics, psychology, every single scientific endeavor (which is the only method we have to make accurate, repeatable predictions) is fundamentally based in logic. Without logic, you can’t make your fallacious circular argument of “god exists, because the bible says so, because the bible is the inspired word of god”.

        Your response highlights the fallacy of correlation, thinking just because you think someone is not specialized in something they must be wrong, dismissing their argument out of hand. You also make the mistake of assuming because I post on the internet I am uneducated in the subject matter, when in fact I do presentations on exactly this subject matter at the university level. Though, the beauty of science is you don’t have to take my word for it, you can simply follow the evidence.

      • http://timfall.wordpress.com/ Tim

        Wow, Edward. Nick didn’t make a single one of those assumptions you ascribe to him. Wow.

      • nmcdonal

        You’re interesting, Edward. I do have to echo Tim and say I don’t resonate with any of the opinions you just presented…especially the one about assuming you’re uneducated – your writing style gives your intelligence away. I actually would be sincerely interested in hearing your lectures!

  • http://www.facebook.com/david.vanlant David Van Lant

    After reading this, I’m not sure whether you have a very good grasp of these fallacies. It’s good to hear that you take them seriously, but you might want to point out their limitations with greater depth.

    I’ve never heard anyone make a statement like the example you use for moral equivalence, Abortion is just like the holocaust”. I have read more than a few authors who have pointed out that the line of reasoning that lead to abortion on demand in the U.S. ran parallel and fed into the reasoning the Nazis used to justify their war machine and the death camps that followed in its wake. Methinks you used a straw man for your example. Your example of an appeal to ignorance may be another one, “You can’t prove God doesn’t exist; therefore He does.” My anecdotal experience has been that this shoe is usually on the atheistic foot—though I haven’t kept a running tally.

    Your example of a slippery slope fallacy is interesting: “If we allow homosexuals to marry, we must allow humans to marry dogs and cats and multiple partners, etc.” As soon as New York State had no sooner legalized same-gender marriage, a suit a party filed suit claiming that his right to multiple marriage partners was being denied. Peter Singer is the Ira W. DeCamp Professor of Bioethics at Princeton University. He says that mutually satisfying sexual activities sometimes occur between people and animals. As long as sex with animals shouldn’t be illegal as long as it doesn’t involve cruelty to the animal, it shouldn’t be illegal. In march of this year, Yale hosted a special sensitivity training event. Sexologist, Dr. Jill McDevitt, invited attendees to consider a range of sexual behaviors including bestiality, incest, and accepting money for sex. She suggested that we ought not judge others concerning stuff like this since we all sources of embarrassment in our lives. Prominent voices in academia are suggesting that consensual sexual unions between adults and minors should be decriminalized. Funny how that works. You might want to reflect upon that one a bit for a future blog maybe

    BTW: Most folks who take logical fallacies seriously don’t use the word “argument” to refer to shouting matches. They claim to use them to help people think through their opinions carefully. O, and idiots aren’t the only folks who fall into the habits fallacious reasoning—it’s a universal “human” habit.

    • http://timfall.wordpress.com/ Tim

      I’ve heard the “abortion as holocaust” statement many times over the years.

    • nmcdonal

      That’s funny, David – you’re the second person to comment that this post is full of straw men…and my reply is – Yes, of course it is! That’s because I’m not actually arguing with anyone in this post…I’m just randomly pulling examples from a hat, real and fictional alike.

  • Art

    One really cannot have a decent discussion anymore. If one disagrees with another’s position, the second party simply attacks: Eg. I say that I have reservations about mixed marriages. My debater automatically accuses me of racism.
    I say that homosexuality is contrary to scripture. Thus, I am homophobic. Ad hominem?

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