* H is false
* H is true
* H is false, and A is lying
* H is true, and A is telling the truth
* H is true, and A is lying
* H is false, and A is telling the truth
If we were all experts or had unlimited time and access to the same information as an argument's proponents, then the genetic fallacy would be hugely useful. With real-world constraints on time and information, it's almost always impossible to evaluate an argument separately from its proponent's commitment to truth.
 Previous HN discussion: https://news.ycombinator.com/item?id=7929203
His eyes lit up as he condescendingly explained to me that I had committed the fallacy of argument from authority. I hadn't PROVED that his system was wrong. I had merely stated that the natural world did not agree with his system. All I had done was show that the universe disagreed with him on quantum mechanics - there was no evidence that the universe was right and he was wrong. There's no reason to assume that the universe gets all the laws of physics right.
By the end of the afternoon, I'd managed to get him to firmly agree that no dog has four legs. His logic:
All cats have four legs.
Therefore, anything that isn't a cat doesn't have four legs.
All dogs are not cats.
Therefore, all dogs do not have four legs.
I pointed out that it was fairly obvious that there do exist dogs with four legs and that the argument was obviously fallacious (specifically at line 2). He chided me for making an Argument from Consequences. Just because his proof that no dog has four legs forces me to abandon my belief that I've encountered dogs with four legs doesn't mean that his proof is wrong. I must simply get used to accepting that I miscounted the number of legs on every dog I've ever met, no matter how unlikely that may seem.
You probably assume that this guy was trolling me. Heck, if someone told me the story, I'd assume that same as well. Unfortunately, he was deadly serious and was exuding a palpable excitement as he made increasingly brilliant and counter-intuitive discoveries during our discussion.
To any philosophy students who wonder why your major has such a dismal reputation, despite having the highest GRE scores of an undergraduate major and producing some truly interesting students, the answer is Greg.
I've seen people severely messed up by their own knowledge of biases. They have more ammunition with which to argue against anything they don't like. And that problem—too much ready ammunition—is one of the primary ways that people with high mental agility end up stupid, in Stanovich's "dysrationalia" sense of stupidity.
 - http://wiki.lesswrong.com/wiki/Dangerous_knowledge
 - http://lesswrong.com/lw/he/knowing_about_biases_can_hurt_peo...
Maybe Greg was just learning about logical fallacies and hadn't gotten all the way through? (Although in that case I don't think his philosophy undergrad was very good, since I think you're supposed to learn that during your bachelor's...)
What I find in practice with these (quite popular) lists of logical fallacies, is that they are usually written with the assumption that the reader is already familiar with the fundaments of logic and is able to correctly apply them.
This work is no different. While I do enjoy the style of the illustrations, we already have a glut of these things skipping to the juicy parts. What we don't have is approachable, accessible works, free of unexplained jargon, that explain for instance, what exactly a "premise" is. How to decide whether a piece of writing or speech contains an argument. How to correctly identify the conclusion of an argument, and connect it with its premises. And so on, for all the list of things that are usually misunderstood about these lists of "fallacies" by people who are… reallly.. genuinely new to logic.
The author starts down this road in his introduction: the rules of logic are not laws of the natural world nor do they constitute all of human reasoning.
Yep, and it's worse than that. Life is not a formal system where the quality of an argument is in any way associated with whether or not it should be heard. That sucks, but that's the way it is. Many terrible arguments are for things you should do. Many seemingly perfect arguments are in support of horrible things.
Human conversation is around persuasion. What these tools of rhetoric give you is a good way to identify cheap ways used to persuade folks -- and call them out on it. It doesn't prevent them from being used at all. In fact, every argument that's not about formal systems has some sort of fallacy as part of it. At the end of the day, you're sitting around weighing the imperfections of each side. And, because the quality of the argument doesn't really reflect the quality of the position being argued, putting too much work into this is a fool's game.
I love these lists, because they show people how others can manipulate them. For the same reason, I think folks should be exposed to a course or two on how legal arguments are made. I see a lot of lawyers on TV who are ready and willing to take any side of any argument -- and convince 90% of the folks watching that they're right. If we want a functioning democracy, we need to fix this.
But for technology folks who tend to think of things in boolean terms, we should remind ourselves that human issues are not geometric proofs for which we are searching for fallacies in an attempt to get the right answer. Instead it's a much tougher situation than that.
That mixes up the quality and sophistication of the arguers with general validity.
The problem is more that decision-making - especially political and economic decision-making - isn't evidence-based.
The fact that economists and politicians use rhetoric instead of reason suggests that you can't have a workable democracy without evidence-based policy.
I'd go further and suggest that knowingly lying to or misleading the public should be a serious crime punishable by jail time.
Lists like the one in this book aren't enough, because so few people understand there's a problem.
Eventually you should move on to the Bayesian/Frequentist definition of Science, but I'd start with the problems with empiricism. Maybe go on to the problems with induction after that. Might want to ask yourself why so many of the most brilliant people in history believed wrong things.
Are you saying that science should never be used to guide policy, because scientific conclusions are always debatable?
As it happens they are - for varying values of 'debatable.'
When you get a reasonable level of informed consensus - preferably one that has a reasonable chance of being undistorted by commercial interests - the debatability stops being interesting or relevant.
The problem isn't that conclusions aren't certain.
The problem is that political decision makers believe their personal opinions about policy and outcomes are at least as valid as those of full-time PhD-qualified professional researchers.
And voters believe them. Because rhetoric.
You don't need to know who Thomas Bayes was to understand how this leads to policy disasters.
You don't even need to believe that experts are always right. You just need to understand that they're more likely to be right than an amateur with a sharp suit, a financial sponsor, and a strong opinion.
What I got is a bunch of back-handed cartoon insults towards the groups the author dislikes.
Still nicely done though, and the pictures are great.
I think there is value in illustrating fallacies not merely in the abstract, but also by allusion to real-world examples—especially when the author's stated goal is to prepare his readers "to identify and avoid them in practice". For the most part, those examples are actual arguments I've encountered people make: that anthropogenic climate change must not be real because addressing it now could hurt the economy, or that Christianity is true because the Bible says so. Orthogonal to the ultimate truth value of global warming or religion, these particular arguments are objectively fallacious, and it is both fair and illuminating to call them out as prominent examples.
Maybe one could argue that the author is himself erecting a straw man by (for another example) lumping together UFO conspiracy theorists with the appeal to ignorance. However, one would have to show that (1) the appeal to ignorance is not actually representative of the kind of arguments most often put forth by UFO enthusiasts (it is, in my experience), and (2) that the author's objective with that passage was to discredit UFO enthusiasts, whereas I believe his objective was simply to demonstrate the fallacy of a specific type of argument which just happens to be most commonly employed (and which the audience will most readily recognize) in that context. Rinse and repeat for all the other allusions.
Great illustrations, though: yes, I think we can all agree on that :)
You over-sensitive liberals just need to grow a thicker skin...
I agree with grandparent for pragmatic reasons -- suggesting this book to a religious friend could easily be misconstrued by said friend as a back-handed insult.
Did you read page 42?
Excerpt: "... circumstantial ad hominem, is any argument that attacks a person for cynical reasons, by making a judgment about their intentions ..."
I probably liked that because appeal to authority is the one I get called out on most often, and now I can post a link in reply, from a Real Logician.
Which would be begging the question, of course, but at least I'd be mixing it up a bit.
Appeal to authority is _still_ a logical fallacy even if the authority is somehow relevant (the high priest says $DEITY exists, and he's clearly an expert of it. Or, the plumber says I need to change the pipes even though I can see they are not broken).
EDIT: the book author would probably argue the appeal to relevant authority may be a good argument, even if not a logical proof.
"Logical fallacies" are not formal logic, and when we're discussing we are forced to make tons of assumptions that are not "logically" guaranteed. Conversation and assessement of a complex reality has far more nuances than what can be handled with a "fallacy list".
The "ad hominen" for example is a very useful guide, because in real life, WHO says something tells us a lot about their motives, interests, possibility of hiding the truth etc, that merely WHAT they say.
Same way, "appeal to authority":
A is an authority on a particular topic
A says something about that topic
A is probably correct
I remember in high school when we were learning about logical fallacies in an English course and subsequently had a class debate about some subject (don't remember what it was). I was one of the two judges, and the teacher assigned two more students to "watch out for logical fallacies". The entire debate devolved into half-baked accusations of logical fallacy (especially accusations of false analogies for literally every analogy presented, regardless of whether or not the analogy was actually valid). It was at that point I figured out that sitting on one's haunches and whining that every argument is a logical fallacy does not an argument make.
A good argument made with bad intentions is still a good argument.
>Same way, "appeal to authority":
This book uses "appeal to irrelevant authority" aka "my dad says you're wrong."
In real life though you don't just have to evaluate the argument, but the whole situation. Who gives the argument, what motive he has for giving it, should you act on his argument now or later, etc.
For one, one can find at least one good argument for any side of an issue (and he can even conceal a better argument for the opposite side knowingly, to get you to do something).
Second, a good argument can still be used to make you do something that has you taken advantage of. It's not as if anybody making an argument to you is neutral and free of interests and motivations.
>This book uses "appeal to irrelevant authority" aka "my dad says you're wrong."
Yes, saw it, but sometimes "appeal to authority" is also found in such lists.
I agree with your parent here, though. There's almost always a good argument for any given thing, and often several.
It's sometimes useful to be able to say "yes, there is a huge pile of good arguments in favor of X here. And I don't have time to address each one. But it's important to note that the author of this pile of good arguments stands to make a great deal of money if people believe X, regardless of its truth."
It's kind-of like how you rarely trust the implicit or explicit claims in super long infomercials, even without examining the veracity of the evidence for the commercial's claims, or taking the time to think up counter-claims.
And if there aren't better arguments for the other things, then those are the things that should be done. If you're telling me that there are almost always equally good arguments for every possible choice in all decisions that are made, I'm disagreeing with that. If that's not what you're saying, I don't know what you're saying.
>It's sometimes useful to be able to say "yes, there is a huge pile of good arguments in favor of X here. And I don't have time to address each one. But it's important to note that the author of this pile of good arguments stands to make a great deal of money if people believe X, regardless of its truth."
It may be important to note, but it's not argumentation. If it's a good argument, accept that it's a good argument and move on. Just because people have a financial interest in an outcome doesn't mean that their arguments for that outcome are tainted in some undetectable way that can't be revealed by examining the argument itself. The personal stake in the outcome could have been initiated by a belief in the validity of the argument, rather than the opposite.
>It's kind-of like how you rarely trust the implicit or explicit claims in super long infomercials, even without examining the veracity of the evidence for the commercial's claims, or taking the time to think up counter-claims.
You don't need to attack the person making the argument or the medium delivering the argument in order to question its premises.
As a tangential but related point, I think this can be a very dangerous position.
Arguments aren't created in a vacuum, and neither is the lion's share of what makes an argument "good". This is true even discounting the fact that the dominant measure of argumentative quality is largely a function of persuasion.
Producing arguments takes a lot of work and money. That's basically the only reason think tanks and law firms exist. It's also where a lot of marketing money -- political or otherwise -- gets spent. Having really good arguments for something mostly indicates you've invested a lot of time, money, or both into constructing those arguments. (edit: note that this is not an indicator that the thing is actually true, which is the root of the problem).
edit: sometimes, as in science, the motive can be fairly pure. In those cases, even though lots of money is spent constructing the arguments, we can still very much trust the veracity of those arguments.
Sometimes, as in the case of many (not all) think tanks, somehow every argument and study produced always re-entrenches and provides support for a pre-existing viewpoint. I'm therefore far more inclined to view these with suspicion, which is really an ad hom but imho justified.
In real life premises are also part of the argument. Aside from mathematics and logic exersizes, there's no discussion that doesn't involve persuassion and arguments about the very premises (and on multiple levels).
That's one of the reasons that the pure mechanistic check of the operations/conclusion part that logical fallacies provide is very nearly useless.
And of course the "checking the premises" part is not mechanistic (that another problem with the formal check), and could also go ad-infinitum. For example, in a moral issue, the premises depend on your values, not some objectively verifiable external truth. On issues of personal interest, the premises depend on what benefits whom. Etc. On political issues the nuances and justifications for the premises are so rich that it's not even worth trying...
If we don't simply agree on the premises, an argument has to be made to support the ones we don't agree on, and that argument will have further premises. If we don't agree on those premises, an argument has to be made to support the ones we don't agree on, and that argument will have further premises.
Eventually we agree on premises, and work our way back up.
>the pure mechanistic check of the operations/conclusion part that logical fallacies provide is very nearly useless.
I think that it's the only important part of evaluating an argument. So our premises differ. If further arguments that you plan to make rest on the premise that the mechanistic checking of the chain of reasoning from premises to conclusion of an argument is very nearly useless, I may be able to recognize the soundness of this hypothetical argument, but never the validity.
> in a moral issue, the premises depend on your values, not some objectively verifiable external truth.
That I claim to have a moral value is an objectively verifiable external truth.
>On issues of personal interest, the premises depend on what benefits whom. Etc.
>On political issues the nuances and justifications for the premises are so rich that it's not even worth trying...
Isn't the entire political process an act of trying?
You kind of answer yourself by identifying the fact that premises are often called into question during the course of an argument:
> If we don't simply agree on the premises, an argument has to be made to support the ones we don't agree on, and that argument will have further premises. If we don't agree on those premises, an argument has to be made to support the ones we don't agree on, and that argument will have further premises.
Your parent's argument was that this can go on forever, and never really grounds out, which demonstrates the flaw in the "argumentation is reducible to mechanistic checking" mentality.
I pretty much agree with your parent, because you can see it even when you go all the way to the ground. A lot of evidence cannot get better than statistical, and statisticians sometimes argue about the best way to approach their field. Even for non-statistical arguments, there's some old beef in mathematics about aoc.
But even for most issues where these foundational questions aren't relevant, doing enough work to formalize arguments is intractable.
> That I claim to have a moral value is an objectively verifiable external truth.
That's not very useful when we're trying to make a moral decision and have different competing values. Most political discussions are utilitarian with a mix of various moral imperatives (e.g. optimize well-being, but abide by the constitution's letter and intent).
> Isn't the entire political process an act of trying?
I think he meant it's not worth trying to treat the arguments as chains of reasoning working from a closed set of premises.
Although I agree that the political process in most places could benefit from a bit more logic, it's worth noting that the political process is the act of trying to get power, not trying to reason soundly :-)
I'm not sure what all of this means. The arguments I'm referring to are formal operations on premises. Premises are the environment that arguments live in, and that's not a vacuum. One party claims to be right, states its premises, and how those premises lead to their conclusion. Attacking that argument means pointing out flaws in the reasoning or the premises. I'm not talking about convincing people, I'm talking about being right.
I don't understand how the rest of your comment relates to argumentation. It sounds more like a comment on marketing - and while marketing may use different arguments of varying quality, it is not in itself an argument.
This is a very vague sentence. What does "how those premises lead to their conclusion" mean?
A formal system?
If not a formal system, then I don't think "being right" is at all well-defined in this sentence. This case converges to the comment below on tractability, which I'll reply to shortly.
If you are referring to a formal system, then the rest of your comment actually is correct. But even in mathematics itself, codifying proof in a formal system is quite rare and practiced only by logicians, certain subfields of CS, and a few early adopters. edit: And, far more to the point, most arguments aren't and can't be mathematical in nature.
> Attacking that argument means pointing out flaws in the reasoning or the premises.
> I don't understand how the rest of your comment relates to argumentation.
The problem is that you're assuming arguments cost nothing -- in terms of money or effort -- to produce. But this simply is not the case. Even in the very best-case scenario of mathematics itself, proof search for even relatively trivial theories is incredibly costly (triple exponential). So even for tiny little factoids that are perfectly well-defined, constructing a valid argument can be intractable.
Now consider the more likely situation where the actual truth of the proposition is effectively unknowable (most of economics and politics) or very difficult to know a priori (a lot of modern science). The resources committed to producing argumentation is probably the most important indicator of the quality of arguments.
> It sounds more like a comment on marketing - and while marketing may use different arguments of varying quality, it is not in itself an argument.
Right, well, I claimed that a lot of marketing is argument construction. So yes, there are other aspects to most marketing as well. But argumentation is certainly part of it.
edit: various small mechanical errors, slight rewording of hastily written sentences.
I disagree with your premise. I believe that all arguments rest of the degree of truth of their premises, and formal methods are used to prove that the degree of truth in the conclusion springs from the degree of truth of the premises. That is definitional - there's nothing else that I would refer to as an argument. Informal fallacies are also formal fallacies, they're just a way of categorizing fallacies that are written in human language rather than mathematical language.
>The problem is that you're assuming arguments cost nothing -- in terms of money or effort -- to produce.
No, I'm not.
>Right, well, I claimed that a lot of marketing is argument construction. So yes, there are other aspects to most marketing as well. But argumentation is certainly part of it.
I'm only interested within this thread about the portion of marketing that is argument construction and analysis, and not in conflating argumentation with rhetoric, marketing, or propaganda. This is not to deny that those fields do use argumentation, along with the sciences, history, literature, theology, and all other fields.
I categorically wasn't referring to the choice of premises, but rather to the cost of finding and evaluating valid arguments themselves, even once premises are settled, for pretty much any interesting/realistic set of premises. That is, in your words, "how those premises lead to their conclusion"
The cost of finding a valid argument, or even deciding rather a prop is true without producing a witnessing argument, is more often than not intractable.
> No, I'm not [assuming arguments cost nothing -- in terms of money or effort -- to produce]
> I'm only interested within this thread about the portion of marketing that is argument construction and analysis, and not in conflating argumentation with rhetoric, marketing, or propaganda.
I assert these two statements are in direct contradiction, since I've provided several examples in this thread of how even and especially appeals to valid argumentation can be used as a form of rhetorical manipulation or propaganda.
Arguments, formal or informal, are costly to produce and even sometimes costly to evaluate.
People with vested interests can and do produce higher-quality arguments than those who don't have the means or simply don't care. Or people who want no action to happen can bog down the conversation. Or people who want something to happen can throw more resources at research and argument construction than their opponents for finite time, and win out.
And all of this even if we assume that every prop has a truth value and that finding that truth value is even decidable, which definitely is not the case.
> It may be important to note, but it's not argumentation.
Isn't it? The end effect is disregarding a certain set of arguments entirely. If completely ignoring the relevance of an argument isn't a powerful argumentative tool, I'm not sure what is.
> You don't need to attack the person making the argument or the medium delivering the argument in order to question its premises.
But isn't that exactly what's happening in the infomercial case? And surely we shouldn't waste our (bounded, finite) time addressing, point-by-point, infomercial arguments?
I have something more practical and less specific in mind as well. You'll find all manner of conspiracy theorists. The more serious ones can bash you over the head with truth claim after truth claim. At some point, in order to avoid endless rabbit holes, it becomes necessary to disregard certain arguments simply because of their source. I typically do this with a 9/11 truther friend (also chem trains and luminati (sp?) and so on), and only consider his factoids non-fictional when I hear them from other sources as well.
There's also an important distinction between attacking the source per se, and attacking the source's credibility/veracity in the argument at hand. We might be talking past each other due to that distinction as well.
edit: ambiguous grammar
Why would you do that? For me it's important to note because premises are assertions, and conflicts of interest raise the likelihood that the premises have been deliberately constructed as to be false or misleading. The idea that I would throw out someone's argument because I've decided that it must be wrong in advance seems ludicrous.
Arguments should rise or fall on their own merits.
>But isn't that exactly what's happening in the infomercial case? And surely we shouldn't waste our (bounded, finite) time addressing, point-by-point, infomercial arguments?
Why exactly wouldn't we, and why would we assume that the claims that are made in infomercials are uniformly false? The reason I don't waste my time vetting the arguments in infomercials is because I'm not currently interested in a juicer, not because of a belief that people who make infomercials are liars, no matter how consistent their arguments or verifiable their premises.
>I typically do this with a 9/11 truther friend (also chem trains and luminati (sp?) and so on), and only consider his factoids non-fictional when I hear them from other sources as well.
I don't. The reason I ignore truthers is because their logic is consistently bad, and their premises are usually demonstrably false. Those reasons came after listening to their arguments, not before. There are plenty of questionable elements in the official narrative, too, but they're not in the same order of magnitude as the leaps of logic made by truthers.
Because I have a finite amount of time in the world. Because we need to decide which policy to enact (or not) today and not in 20 years. Because producing and evaluating arguments takes time, and -- most importantly -- because bad actors exist.
> The idea that I would throw out someone's argument because I've decided that it must be wrong in advance seems ludicrous.
Witness e.g. Microsoft trolling standards committees into non-existence back in the day. I'm sure they had an endless supply of valid and brilliantly illustrated technical points to consider, but at some point you have to say "you're a bad actor, and I'm going to start disregarding your arguments because you're making the decision process intractable and, like it or not, something needs to be done eventually".
> The reason I don't waste my time vetting the arguments in infomercials is because I'm not currently interested in a juicer, not because of a belief that people who make infomercials are liars, no matter how consistent their arguments or verifiable their premises.
Right. You have an a priori opinion that you don't need a juicer (or whatever), and you stick with that instead of wasting time considering the commercial's many valid arguments about how buying a juicer will totally enhance your life.
edit: it's not that the infomercial guys are liars per se. It's just that you've decided that evaluating their arguments for why their product will make you happier probably isn't worth your time. And in most cases, I claim that most people make that decision precisely because the source is a paid advertisement. That's an ad hom dismissal of the argument that juicers save marriages (or whatever, can you tell I don't watch infomercials? :-) ).
> Those reasons came after listening to their arguments, not before.
It's the particular person, not any of his theories per se. If one of these theories was mentioned by another person (even someone I didn't know), I would probably investigate if I found the time. But this particular person proved his signal-to-noise ratio is too high long ago, so I stopped listening. That's ad hom, but it's also a cost-effective. I don't want to spend my finite time on this planet objectively analyzing the evidence for every conspiracy theory my friend happens to latch on to. And I think that's rational, even though it's ad hom. And the reason is that evaluating the veracity of arguments is time consuming, and I have finite time.
It doesn't take 20 years to evaluate an argument. If, on a case by case basis, there's an argument to be made that any of the proposed answers would be better than delaying a decision, then that's an argument too, with premises and reasoning that need to be evaluated.
>Right. You have an a priori opinion that you don't need a juicer (or whatever), and you stick with that instead of wasting time considering the commercial's many valid arguments about how buying a juicer will totally enhance your life.
Maybe I've phrased it wrongly, then. If I'm watching an infomercial, I'm evaluating its arguments. I don't seek out infomercials, because I'm not interested in a juicer. It usually doesn't take very long for infomercials about juicers to make a dubious health claim when I do catch them, though, so in the past I've rejected purchasing one on the merits.
edit: added "usually", in that I've watched infomercials that never made a dubious claim, and I've used products that have been featured in infomercials and been entirely satisfied.
Yes it can, and even in barely contrived scenarios if your proof calculus isn't nice enough.
More importantly, in very practical cases even not assuming adversarial (e.g. Microsoft on standards committees), it most definitely can take 20 years to find a valid argument. Exponential growth is serious stuff. Triple exponential growth is just stupid fast.
If you can't wait 20 years, then you have to move forward with arguments for not-valid-but-sometimes-true cases. And in this case, the agent with the most compute power can generate contradictions for opposing props more quickly and can also generate true instances matching his policy preferences more quickly. Thus, bounded argumentation often inherently favors the more resource-rich adversary.
And the same thing works in more informal settings as well.
One way to cope with this is to disregard arguments from known bad actors. We can discuss rather that's the correct course of action, but the need is a provable fact of the most useful formal systems and an observable fact of informal argumentation (I'm still not sure which you want to discuss, since your assumptions make me think you view all arguments as formal systems, but most arguments -- including this one -- clearly aren't in any meaningful sense of the word formalized).
Edits - there is another thing I do not understand. The breadcrumbs in the top left. Are they breadcrumbs? The > implies direction. Are the middle categories sorted? Is it a list of categories without hierarchies?
Informal Fallacy › Unwarranted Assumption › False Dilemma
All pages have Informal Fallacy.
Not 34. ;-)
> One should keep in mind that such arguments are fallacious only when they deal with propositions with objective truth values