Thou Shalt Not Commit Logical Fallacies [poster]
yourlogicalfallacyis.com
yourlogicalfallacyis.com
I was getting annoyed at the oversimplified, vague, and/or unclear explanations on the poster. It's great to have a poster cataloging logical fallacies, but it's not so great if it doesn't actually explain them very well.
So I go to the home page of the site, where the first sentence reads:
"A logical fallacy is usually what has happened when someone is wrong about something."
FACEPALM.
The validity of a logical argument has NOTHING to do with the actual veracity (rightness or wrongness) of the propositions. This is basic stuff. Logic is the process of figure out what other things we know based on what we already know. If what we think we know is wrong, then we can make all the logically correct arguments we want and we'll still be drawing wrong conclusions.
On a completely different coin, nobody ever won an argument by treating it as a game of Spot the Logical Fallacy. All you'll win playing that game is a reputation for being insufferable.
It's worse than that. Paying too much attention to rigour and the mathematical validity of arguments unduly privileges strict logical argumentation over "traditional" informal argumentation.
Outside of technical areas there are almost no arguments amenable to pure logical argumentation. Think about it - why would you be arguing over something that can be mechanically deduced with certainty? In most circumstances logical syllogisms and the like are used only as "glue" to hold the real argument together.
We should recognise that arguments using these "fallacies" don't have absolute persuasive power, but we shouldn't go so far as to say that they can have no persuasive power at all.
Thereby committing a fallacy himself in the form of a straw man.
For example I often see people winning casual arguments by overusing emotive language , belittling the opinion of their opponent or by misrepresenting (or misunderstanding) what they are saying.
You're right that the logical coherence of an argument doesn't have any intrinsic bearing upon the proposition that it supports being either true or false, but this does not invalidate the point that when people are wrong, they're more often than not guilty of committing fallacies in both their reasoning and their defence of their point.
Also, the idea of the site is to be very simple rather than comprehensive. Preaching to the choir is all good and well, but I'm more interested in spreading knowledge to children and people who haven't been exposed to or understood these concepts previously (however many uber nerds have emailed me saying that they've enjoyed it and hung the poster up).
From the FAQ section: The point of the site is to make common logical fallacies easily understood, so listing every single one isn't really what it's about. If you want to learn more about logical fallacies check out this comprehensive interactive list of all the formal and informal fallacies.
Hasty generalization :)
I have found that when people are wrong, it's usually because they are incorrect about the facts that they're basing their argument on.
That said, I will say that the poster explanations were frustrating for me. I've studied formal logic via computer science, but not enough argumentation or philosophical logic -- so some of these fallacies were new to me. For example "no true scotsman" -- but the explanation did nothing to help me understand it. I'm type of person who learns by example, but your examples are so cutesy and weird that I can't actually relate them back to anything useful. Something about sugar in porridge? What I want is to be able to recognize these when I see them, but I'm just not getting it from your explanation. Real-world examples would be MUCH better.
Part of why I'm frustrated is I've been wishing for a resource like this for a long time -- someone who really understands argumentation, clearly and simply explaining logical fallacies, with real-world examples. I've read about "straw man" repeatedly, over and over -- definition after definition -- and I still am not confident that I could identify it if I saw it. Very frustrating. Feels like a lost opportunity. Maybe it's working for others, not me though. sorry
On a more constructive note, it seems to me that discussions of fallacies are nearly useless without first talking about deductive/inductive logic, validity & soundness, strong/weak and cogency.
I've noticed a common trend in arguments of the following sort:
A: No Communist dictatorship has ever had long term economic prosperity. B: What about the United States? It's had incredible economic growth for over a hundred years. A: The United Sates isn't an communist dictatorship. B: That's the No True Scotsman fallacy.
I won't argue that the Americans you talked to can give a reasoned condemnation of communism, but with its historical baggage the burden tends to swing the other way. It's hard to have a rational argument with a lot of people about Nazism, but it's hard to criticise people for trusting that it's not for them.
This is on the poster.
Slippery slope -- Asserting that if we allow A to happen, then Z will consequently happen too, therefore A should not happen.
Slippery slope is not necessarily a fallacy -- it is only a fallacy if the warrant is extreme. If we were arguing about dropping lit cigarette butts into the trash and we both agreed that fires were bad and I made the claim that we shouldn't drop cigarettes in the trash because they often cause fires (and cited data to that effect) there would be no fallacy in my argument.
Appeal to authority -- Using the opinion or position of an authority figure, or institution of authority, in place of an actual argument.
This one actually infuriates me because it may be the most wrongly used logical fallacy. First, because most people who use this argument are not making a logical deduction, they're making a statistical argument. To cite from Wikipedia:
The appeal to authority may take several forms. As a statistical syllogism, it will have the following basic structure:[1] Most of what authority a has to say on subject matter S is correct. a says p about S. Therefore, p is correct. The strength of this argument depends upon two factors:[1][2] The authority is a legitimate expert on the subject. A consensus exists among legitimate experts on the matter under discussion.
There is nothing wrong with this argument. The example given in the poster is very bad. As a PL student I have a bit of experience with formal methods and I'll remind everyone that the only things which can be proven using logic are those which follow directly from the definitions. In real arguments, these structures basically never exist. The truth never follows necessarily from the things people say, it's almost always a statistical argument. The fact that medical authorities used to think wrong things about the body didn't necessarily mean that it is or was wrong to believe in the body of scientific knowledge at the time. It only means that you have to be aware of the error margin in your statistics.
http://www.yourlogicalfallacyis.com/appeal-to-authority
http://www.yourlogicalfallacyis.com/slippery-slope
Your concerns seem to be addressed there.
Second, even if the extra links on the site were correct I don't see why that would make the poster itself any less wrong.
In any case, I see this poster as a cheat sheet: not something to learn from, but a quick reference for someone who has already done their homework and learned about those logical fallacies.
Argument from authority -- It is important to note with this fallacy that authorities in given fields may very well have valid arguments, and that one should not dismiss another's experience and expertise. To form an argument, however, one must defend it on its merits i.e. know why the person in authority holds the particular position that they do.
Only vaguely. You don't actually have to know what general relativity is or how it works to form an argument based on the statistical likelihood of physicists being correct. You don't really have to know "why" the person in authority holds their opinion, only that they are both an expert on the topic they are covering and that there is a general consensus among other experts on the same topic.
It is, of course, entirely possible that the opinion of a person or institution of authority is wrong; therefore the authority that such a person or institution holds does not have any intrinsic bearing upon whether their claims are true or not.
I'm not sure what this is trying to say, but there's certainly justifiable basis in believing that person's authority has an intrinsic bearing on the probability that their claim is true.
How is the quoted definition at all useful -- to either logicians or laymen?
It's only a fallacy to suggest that a slippery slope is logically entailed, i.e. to assert without further argument that it's logically necessary for Z to happen if A happens simply because Z is a more extreme form of A.
But slippery slopes certainly do exist empirically, especially with respect to politics, and given the actual nature of a particular political milieu, it can be entirely reasonable to suggest that implementing one policy makes it more likely for a more extreme version of that policy to come about in the future.
> Appeal to authority -- Using the opinion or position of an authority figure, or institution of authority, in place of an actual argument.
Same thing here. As you've said, it's entirely reasonable to apply a heuristic that gives greater credibility to a source whose statements have previously proven useful or valid than one that hasn't.
The fallacy of the appeal to authority is in assuming that a given statement is true because an 'expert' has made it, but it's entirely reasonable to expect that a person you regard as an expert is more likely to make statements that are valid in their own right.
The primary fallacy of those who excessively discuss logical fallacies is the assumption that most arguments actually are applications of deterministic logic intended to assert an unambiguously correct answer to an unambiguous question in the first place. Most arguments really involve the application of heuristics in complex and stochastic contexts, in order to establish an understanding that's marginally more useful than the status quo. Many arguments also involve attempts to reconcile competing conceptions of the desired end state, and are not simply disputes regarding the reasoning applied to obtain a presumptively agreed-upon end state. Formal deductive logic isn't the most relevant template in either of these scenarios.
For example: "the british medical association has said that smoking increases risk of cancer" therefor it is best not to smoke.
At which point you will get "Aha! You just committed appeal to authority and a slippery slope fallacy, you must be wrong!".
I suppose this is partly because in real life arguments we very rarely have sufficient knowledge in any subject to make concrete formal arguments based on direct observations, we are usually discussing the likelyhood of different things being true.
“Aristotle maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives' mouths.” ― Bertrand Russell, The Impact of Science on Society
There's a quote which I thought was from a friend of mine, but when I asked him, he denies ever saying it, so I'm not sure where it's from: "Philosophy is the history of bad arguments." I just quoted Russel, because he's a bit more of a respected authority on the subject.
While 'most of history' is a long time, the knowledge of a round earth has been around (and popular) since around 300 BC. It may be true that humans, and even that written (let alone verbal) histories, have been around for much more than 2000 years, the commonness of this myth warrants a different example. You wouldn't want to be seen supporting a position that only exists because many people think it is true, now would you :D
Sometime after I loaded the landing page but before I could click a link, the account/site went "poof".
You can also add it to Zazzle yourself and get it for a little cheaper, just make sure you put in the right dimensions, i.e. A2 (594x420mm or 23.4 x 16.5 inches) or A1 (841x594mm or 33.1 x 23.4 inches)
So now I think they are heuristics rather than absolute measurements. And we should use them to teach ourselves something about logic, but not others.