6 ms·

Logical fallacies

91 points by uladzislau 14y ago

lowboy 14y ago
I look forward to replying to misguided online arguments with a simple link. If everyone started doing that, no one would be committing logical fallacies anymore! https://yourlogicalfallacyis.com/slippery-slope https://yourlogicalfallacyis.com/slippery-slope
- malkia 14y ago
  I have a sense that what you've said (If everyone started doing that) is another form of fallacy, but I myself might be putting some fallacy here... oh well...
  - lowboy 14y ago
    Whoosh
    - Zuider 14y ago
      Was your first comment intended as irony? When arguing with others it is best to employ the principle of charity, even to the point of improving the other party's arguments to make them as strong as possible, and then pointing out where you think they are wrong. It is best to study fallacies in order to avoid making them, rather than throwing them at others in the manner of the proverbial religious hypocrite who 'read ye good booke in order to rake all the blessings unto himself, and to shovel all the curses unto his neighbours'.
      - lowboy 14y ago
        I agree that the principle of charity should be employed. Sometimes though, the conversation benefits from someone knowing why their arguments aren't solid.
- comex 14y ago
  And sure enough, someone has done this in another front page post: https://news.ycombinator.com/item?id=5391677 https://news.ycombinator.com/item?id=5391677 (edit: which is why, even if the parent is somewhat tongue in cheek, I'm complaining about it, heh.) The problem is that fallacies are not always fallacious. In fact, I'd guess that the majority of online arguments which people label with names of fallacies are not completely invalid, though they may be less valid than other arguments. The fallacy in calling something a fallacy, so to speak, is that while an argument that includes a fallacy cannot rigorously prove that something is true, your typical discussion where fallacies are brought up is not an attempt to rigorously prove something, and cannot be, because it's about an inherently subjective statement or one which not enough information is available to prove or disprove. To advance the discussion in that case, an argument need only demonstrate that the statement is somewhat likely to be true - from a Bayesian perspective, that a rational actor should assign a higher probability to the statement being true than if he did not consider the argument - and many "fallacious" arguments satisfy this criterion. For example, a slippery slope argument is best substantiated by justifying why doing X is actually likely to lead to doing Y, but even without substantiation, pointing out that Y is a possible outcome logically makes X a slightly worse idea to consider, and there is a lot of room in between for partially but not fully substantiable arguments. Or to pick a random example from the site, an appeal to nature is fallacious because "because something is 'natural' it is therefore valid" is not necessarily true, but while it's easy to put excessive credence in the correlation between "natural" and "good", that doesn't mean there is no correlation: in the absence of stronger evidence to the contrary, "it's good because it's natural" is a valid starting point. Even the mainstay of fallacies, ad hominem, is subject to this: because arguing about subjective points necessarily involves taking a bunch of factors and assigning them essentially arbitrary weights (theoretically based on one's experience of what factors have proved accurate in the past, but still arbitrary), it's perfectly valid to argue that because someone has demonstrated bad judgement in the past (especially about a similar judgement call, as in the post I cited), their assignment of weights in this case is more likely to be incorrect. A response of "this is fallacy X" is itself quite valid as a heuristic argument - an argument containing a fallacy is less likely to be valid than an argument not containing a fallacy - but it's not sufficient to completely dismiss most arguments, and those who would use the rhetoric of logical fallacies to purport to do so, linking to a well-designed web page that says "your argument is invalid", are essentially committing the fallacy of arguing from authority. While certainly not all arguments deserve well-reasoned responses, just claiming that an argument is a fallacy is generally not a well-reasoned response, and in practice it tends to be rude and unproductive. Linking to a description of a logical fallacy carries a certain implication of "your argument is so bad that you need to be educated about the basics of fallacies". It's like saying RTFM - reasonable in response to a poorly formed or low-effort question, but rude in response to a high-quality one.
tsm 14y ago
As good as it is to identify these, it's worth pointing out that another fallacy is the assumption that the point a fallacious argument is trying to prove is wrong because it has a fallacy. It's possible to be right but still commit a fallacy in your argument.
- huckfinnaafb 14y ago
  This is a fallacy listed, "the fallacy fallacy", first column second row on the left with the symbol of a fractal.
- potatolicious 14y ago
  Fallacies do not in and of themselves disprove an argument - but I usually see them as a barometer for the quality of discourse and the character of the person making the argument. An argument strongly compromised by fallacies, made by someone otherwise intelligent, suggests to me disingenuity and intellectual dishonesty - and it affects how willing I am willing to engage in debate in return.
tsm 14y ago
I've found Wikipedia's list[0] to be both more complete and more Ctrl-F -able, but this is certainly attractively laid out and has good descriptions. 0: http://en.wikipedia.org/wiki/List_of_fallacies http://en.wikipedia.org/wiki/List_of_fallacies
- jrichardson 14y ago
  hey, site owner here. the idea for the site was to show the most common fallacies in clear language and pretty visuals. For a comprehensive list i highly recommend the fallacy files' taxonomy: www.fallacyfiles.org/taxonomy.html
JacobAldridge 14y ago
I studied formal Logic in high school (sadly, we were the second last cohort before it was discontinued due to lack of interest). Undoubtedly one of the best decisions I ever made, for examining my own thinking and arguments as much as those around me. Logical Fallacies was one of my favourite elements. (Deductive logic is fabulous as well, but of limited application in a real world of probabilities.) If I could wave my magic wand and change education, logic would be right up there with entrepreneurial economics as a mandatory class to support kids understanding how the world works (and how it can work in their favour).
tsewlliw 14y ago
Read this as a list of effective ways to communicate your point beyond mere facts. If anyone has ever said your appeals are dry, sprinkle in these lightly.
tedsanders 14y ago
The biggest fallacy I'd add is Mood Affiliation: http://marginalrevolution.com/marginalrevolution/2011/03/the-fallacy-of-mood-affiliation.html http://marginalrevolution.com/marginalrevolution/2011/03/the...
andrewflnr 14y ago
The first one it showed me was "slippery slope", and I don't think that's a fallacy. It may be an invalid argument or prediction depending on the evidence, but it's not structurally invalid the way ad hominem and tu quoque are. Why is it there?
- jarrett 14y ago
  I'm assuming it's there because it's a popular bad argument. Well, it's an argument that's often bad. Slippery slopes can actually happen in the real world. But I suppose anyone making a slippery slope argument has the burden of showing that the slipping is likely to occur.
  - andrewflnr 14y ago
    Yes, the burden of proof for a prediction (slippery slope is an instance of a prediction) lies with the party making the prediction. The exact same goes for any argument, and such a prediction should get the same respect as any other potentially flawed argument. If someone is saying "A will cause Z OMG!" without a strong causal chain, the fallacy you want is probably "non sequitur", or you point out what other thing is wrong with their reasoning. But you don't just assume the argument is invalid, as you do with formal fallacies, because slippery slopes are indeed real. At the risk of going too meta, someday am I going to have to deal with some idiot who thinks "slippery slope" is a formal fallacy, because they were all lumped together like this? If the site gets enough traffic, it will get some people who can't tell the difference, who will come away with the wrong impression. Not that many, but the possibility is, IMO, an indicator that lumping them together like this is a bad idea.
    - nitrogen 14y ago
      At the risk of going too meta, someday am I going to have to deal with some idiot who thinks "slippery slope" is a formal fallacy... It already happens elsewhere. You can observe an ongoing trend and justify the expectation that it will continue using the motivations and past behavior of the actors involved, and someone will still say, "Slippery slope, I win!"
zeteo 14y ago
As long as you're not doing pure mathematics, you can't always speak on purely logical ground. Aristotle himself, who invented logic and whose picture is on this poster, wrote a different book called The Art of Rhetoric in which he fully approves of deploying e.g. appeals to emotion or authority. Most of these "fallacies" are actually good heuristics within normal discourse: even if they don't produce full logical confidence, they are still very useful in ambiguous or time-sensitive contexts (a.k.a. everyday life).
- jiggy2011 14y ago
  Yes, this is very true. It is pretty close to impossible to have an argument at bar or internet forum level without committing something that resembles a logical fallacy. Refer to something written by an expert rather than demonstrating it directly yourself? Appeal to authority. Suggest that a particular source of information may be unreliaible? Ad hominem Voice a concern over the direction some policy appears to be taking? Slippery Slope. Many arguments are also based on statistics rather than directly on logic. Logical fallacies can be used to expose highly axiomatic thinking though.
  - lowboy 14y ago
    Your examples are too broad and/or poorly defined. An appeal to authority fallacy has to be without reason backing up the appeal other than the fact that they are an authority. You can suggest that a source of information might be unreliable because of a poor track record in the the domain, or a conflict of interest - that's not ad hominem. One can speak against the direction of a policy without committing a slippery slope fallacy by not making unsubstantiated claims about what will happen. If you can cite examples of similar policies that have led to effect Y happening with rational explanations for the causes along the way, then that would avoid the fallacy.
    - jiggy2011 14y ago
      Well, for example if somebody asked me the circumference of the earth and I replied with "40,075 km" how do I actually know that? I certainly have never measured it, so all I can do is cite sources of information which are assumed to be authorities. I can be relatively confident in my reply by citing multiple sources of information but I'm still ultimately relying on something I can't realistically provide other evidence for. According to wikipedia the second could possibly fall under "Circumstantial Ad hominem" in that suggesting a source has bias does not necessarily make them incorrect. Though this depends on the nature of the argument. I think the third is more tricky to pin down because it is going to depend again on the nature of the argument. You may suggest concern about some policy without a concrete example of X leading to Y because it may not have happened before. But again this depends on the nature of the argument. I think my problem is more with the way in which logical fallacies are abused in internet arguments rather than the fallacies themselves. For example somebody saying "You are wrong to be concerned about policy X because slippery slope fallacy".
DanielRibeiro 14y ago
Another great visualization of logical fallacies: http://www.informationisbeautiful.net/visualizations/rhetological-fallacies/ http://www.informationisbeautiful.net/visualizations/rhetolo...
hnriot 14y ago
What a wonderfully worded website and poster. Wit and humor and intelligence are a powerful combination.
suyash 14y ago
Reminds me of my logic class in college, very well laid out and it serves as a reminder to watch our yourself and others while falling for one of these fallacies.
d4n3 14y ago
Have you considered the .is TLD? yourlogicalfallacy.is/ad-hominem
evolve2k 14y ago
5. Potato
lucb1e 14y ago
I can't help but think of politicians while reading these.
notum 14y ago
A blog (and a book) related to the subject: http://youarenotsosmart.com/ http://youarenotsosmart.com/ I really enjoyed the book, fun read.
ableal 14y ago
Also: http://en.wikipedia.org/wiki/The_Art_of_Being_Right http://en.wikipedia.org/wiki/The_Art_of_Being_Right , "The Art of Being Right: 38 Ways to Win an Argument (1831) [...] written by the German philosopher Arthur Schopenhauer in sarcastic deadpan." Rhetorical training was a paying job back in the days when public speaking was a major source of entertainment. It's a pity it is not more widely taught, for self-defense purposes.

91 points by uladzislau 14y ago

I look forward to replying to misguided online arguments with a simple link. If everyone started doing that, no one would be committing logical fallacies anymore! https://yourlogicalfallacyis.com/slippery-slope https://yourlogicalfallacyis.com/slippery-slope

malkia 14y ago
I have a sense that what you've said (If everyone started doing that) is another form of fallacy, but I myself might be putting some fallacy here... oh well...
- lowboy 14y ago
  Whoosh
  - Zuider 14y ago
    Was your first comment intended as irony? When arguing with others it is best to employ the principle of charity, even to the point of improving the other party's arguments to make them as strong as possible, and then pointing out where you think they are wrong. It is best to study fallacies in order to avoid making them, rather than throwing them at others in the manner of the proverbial religious hypocrite who 'read ye good booke in order to rake all the blessings unto himself, and to shovel all the curses unto his neighbours'.
    - lowboy 14y ago
      I agree that the principle of charity should be employed. Sometimes though, the conversation benefits from someone knowing why their arguments aren't solid.
comex 14y ago
And sure enough, someone has done this in another front page post: https://news.ycombinator.com/item?id=5391677 https://news.ycombinator.com/item?id=5391677 (edit: which is why, even if the parent is somewhat tongue in cheek, I'm complaining about it, heh.) The problem is that fallacies are not always fallacious. In fact, I'd guess that the majority of online arguments which people label with names of fallacies are not completely invalid, though they may be less valid than other arguments. The fallacy in calling something a fallacy, so to speak, is that while an argument that includes a fallacy cannot rigorously prove that something is true, your typical discussion where fallacies are brought up is not an attempt to rigorously prove something, and cannot be, because it's about an inherently subjective statement or one which not enough information is available to prove or disprove. To advance the discussion in that case, an argument need only demonstrate that the statement is somewhat likely to be true - from a Bayesian perspective, that a rational actor should assign a higher probability to the statement being true than if he did not consider the argument - and many "fallacious" arguments satisfy this criterion. For example, a slippery slope argument is best substantiated by justifying why doing X is actually likely to lead to doing Y, but even without substantiation, pointing out that Y is a possible outcome logically makes X a slightly worse idea to consider, and there is a lot of room in between for partially but not fully substantiable arguments. Or to pick a random example from the site, an appeal to nature is fallacious because "because something is 'natural' it is therefore valid" is not necessarily true, but while it's easy to put excessive credence in the correlation between "natural" and "good", that doesn't mean there is no correlation: in the absence of stronger evidence to the contrary, "it's good because it's natural" is a valid starting point. Even the mainstay of fallacies, ad hominem, is subject to this: because arguing about subjective points necessarily involves taking a bunch of factors and assigning them essentially arbitrary weights (theoretically based on one's experience of what factors have proved accurate in the past, but still arbitrary), it's perfectly valid to argue that because someone has demonstrated bad judgement in the past (especially about a similar judgement call, as in the post I cited), their assignment of weights in this case is more likely to be incorrect. A response of "this is fallacy X" is itself quite valid as a heuristic argument - an argument containing a fallacy is less likely to be valid than an argument not containing a fallacy - but it's not sufficient to completely dismiss most arguments, and those who would use the rhetoric of logical fallacies to purport to do so, linking to a well-designed web page that says "your argument is invalid", are essentially committing the fallacy of arguing from authority. While certainly not all arguments deserve well-reasoned responses, just claiming that an argument is a fallacy is generally not a well-reasoned response, and in practice it tends to be rude and unproductive. Linking to a description of a logical fallacy carries a certain implication of "your argument is so bad that you need to be educated about the basics of fallacies". It's like saying RTFM - reasonable in response to a poorly formed or low-effort question, but rude in response to a high-quality one.

tsm 14y ago

As good as it is to identify these, it's worth pointing out that another fallacy is the assumption that the point a fallacious argument is trying to prove is wrong because it has a fallacy. It's possible to be right but still commit a fallacy in your argument.

huckfinnaafb 14y ago
This is a fallacy listed, "the fallacy fallacy", first column second row on the left with the symbol of a fractal.
potatolicious 14y ago
Fallacies do not in and of themselves disprove an argument - but I usually see them as a barometer for the quality of discourse and the character of the person making the argument. An argument strongly compromised by fallacies, made by someone otherwise intelligent, suggests to me disingenuity and intellectual dishonesty - and it affects how willing I am willing to engage in debate in return.

tsm 14y ago

I've found Wikipedia's list[0] to be both more complete and more Ctrl-F -able, but this is certainly attractively laid out and has good descriptions. 0: http://en.wikipedia.org/wiki/List_of_fallacies http://en.wikipedia.org/wiki/List_of_fallacies

jrichardson 14y ago
hey, site owner here. the idea for the site was to show the most common fallacies in clear language and pretty visuals. For a comprehensive list i highly recommend the fallacy files' taxonomy: www.fallacyfiles.org/taxonomy.html

JacobAldridge 14y ago

I studied formal Logic in high school (sadly, we were the second last cohort before it was discontinued due to lack of interest). Undoubtedly one of the best decisions I ever made, for examining my own thinking and arguments as much as those around me. Logical Fallacies was one of my favourite elements. (Deductive logic is fabulous as well, but of limited application in a real world of probabilities.) If I could wave my magic wand and change education, logic would be right up there with entrepreneurial economics as a mandatory class to support kids understanding how the world works (and how it can work in their favour).

tsewlliw 14y ago

Read this as a list of effective ways to communicate your point beyond mere facts. If anyone has ever said your appeals are dry, sprinkle in these lightly.

tedsanders 14y ago

The biggest fallacy I'd add is Mood Affiliation: http://marginalrevolution.com/marginalrevolution/2011/03/the-fallacy-of-mood-affiliation.html http://marginalrevolution.com/marginalrevolution/2011/03/the...

andrewflnr 14y ago

The first one it showed me was "slippery slope", and I don't think that's a fallacy. It may be an invalid argument or prediction depending on the evidence, but it's not structurally invalid the way ad hominem and tu quoque are. Why is it there?

jarrett 14y ago
I'm assuming it's there because it's a popular bad argument. Well, it's an argument that's often bad. Slippery slopes can actually happen in the real world. But I suppose anyone making a slippery slope argument has the burden of showing that the slipping is likely to occur.
- andrewflnr 14y ago
  Yes, the burden of proof for a prediction (slippery slope is an instance of a prediction) lies with the party making the prediction. The exact same goes for any argument, and such a prediction should get the same respect as any other potentially flawed argument. If someone is saying "A will cause Z OMG!" without a strong causal chain, the fallacy you want is probably "non sequitur", or you point out what other thing is wrong with their reasoning. But you don't just assume the argument is invalid, as you do with formal fallacies, because slippery slopes are indeed real. At the risk of going too meta, someday am I going to have to deal with some idiot who thinks "slippery slope" is a formal fallacy, because they were all lumped together like this? If the site gets enough traffic, it will get some people who can't tell the difference, who will come away with the wrong impression. Not that many, but the possibility is, IMO, an indicator that lumping them together like this is a bad idea.
  - nitrogen 14y ago
    At the risk of going too meta, someday am I going to have to deal with some idiot who thinks "slippery slope" is a formal fallacy... It already happens elsewhere. You can observe an ongoing trend and justify the expectation that it will continue using the motivations and past behavior of the actors involved, and someone will still say, "Slippery slope, I win!"

zeteo 14y ago

As long as you're not doing pure mathematics, you can't always speak on purely logical ground. Aristotle himself, who invented logic and whose picture is on this poster, wrote a different book called The Art of Rhetoric in which he fully approves of deploying e.g. appeals to emotion or authority. Most of these "fallacies" are actually good heuristics within normal discourse: even if they don't produce full logical confidence, they are still very useful in ambiguous or time-sensitive contexts (a.k.a. everyday life).

jiggy2011 14y ago
Yes, this is very true. It is pretty close to impossible to have an argument at bar or internet forum level without committing something that resembles a logical fallacy. Refer to something written by an expert rather than demonstrating it directly yourself? Appeal to authority. Suggest that a particular source of information may be unreliaible? Ad hominem Voice a concern over the direction some policy appears to be taking? Slippery Slope. Many arguments are also based on statistics rather than directly on logic. Logical fallacies can be used to expose highly axiomatic thinking though.
- lowboy 14y ago
  Your examples are too broad and/or poorly defined. An appeal to authority fallacy has to be without reason backing up the appeal other than the fact that they are an authority. You can suggest that a source of information might be unreliable because of a poor track record in the the domain, or a conflict of interest - that's not ad hominem. One can speak against the direction of a policy without committing a slippery slope fallacy by not making unsubstantiated claims about what will happen. If you can cite examples of similar policies that have led to effect Y happening with rational explanations for the causes along the way, then that would avoid the fallacy.
  - jiggy2011 14y ago
    Well, for example if somebody asked me the circumference of the earth and I replied with "40,075 km" how do I actually know that? I certainly have never measured it, so all I can do is cite sources of information which are assumed to be authorities. I can be relatively confident in my reply by citing multiple sources of information but I'm still ultimately relying on something I can't realistically provide other evidence for. According to wikipedia the second could possibly fall under "Circumstantial Ad hominem" in that suggesting a source has bias does not necessarily make them incorrect. Though this depends on the nature of the argument. I think the third is more tricky to pin down because it is going to depend again on the nature of the argument. You may suggest concern about some policy without a concrete example of X leading to Y because it may not have happened before. But again this depends on the nature of the argument. I think my problem is more with the way in which logical fallacies are abused in internet arguments rather than the fallacies themselves. For example somebody saying "You are wrong to be concerned about policy X because slippery slope fallacy".

DanielRibeiro 14y ago

Another great visualization of logical fallacies: http://www.informationisbeautiful.net/visualizations/rhetological-fallacies/ http://www.informationisbeautiful.net/visualizations/rhetolo...

hnriot 14y ago

What a wonderfully worded website and poster. Wit and humor and intelligence are a powerful combination.

suyash 14y ago

Reminds me of my logic class in college, very well laid out and it serves as a reminder to watch our yourself and others while falling for one of these fallacies.

d4n3 14y ago

Have you considered the .is TLD? yourlogicalfallacy.is/ad-hominem

evolve2k 14y ago

5. Potato

lucb1e 14y ago

I can't help but think of politicians while reading these.

notum 14y ago

A blog (and a book) related to the subject: http://youarenotsosmart.com/ http://youarenotsosmart.com/ I really enjoyed the book, fun read.

ableal 14y ago

Also: http://en.wikipedia.org/wiki/The_Art_of_Being_Right http://en.wikipedia.org/wiki/The_Art_of_Being_Right , "The Art of Being Right: 38 Ways to Win an Argument (1831) [...] written by the German philosopher Arthur Schopenhauer in sarcastic deadpan." Rhetorical training was a paying job back in the days when public speaking was a major source of entertainment. It's a pity it is not more widely taught, for self-defense purposes.