Defending 42 Fallacies

One thing I have found interesting about making my popular (in both senses) work on fallacies readily available is that it generates some rather hostile criticisms. In fact, one such criticism, posted as a comment by argumentics,  was removed from this blog site.

When I found that the comment had been deleted, I was somewhat split in my view. On the one hand, allowing comments that go beyond criticism into hostility can be damaging to a blog by allowing the conversation to spiral down rapidly. On the other hand, criticisms should be taken seriously and addressed.

Of course, if someone wants his or her criticism to be taken seriously and considered an addition to the conversation, that person should present his/her comments in a suitable way. That is, in a civil manner.

While I will not reproduce the entirety of the deleted comments, I will present the criticisms made by this person (without the condescending remarks and personal attacks) and reply to them. This is mainly because I do not like to walk away from an attack.

Also, the criticisms raised by argumentics are not new-over the years the same sort of comments have arrived in my email. By addressing what I take to be misinterpretations of my work I hope to lower the chance of other people making the same mistakes.

Argumentics begins by claiming that there is “no single difference between your example of “Inductive Argument” and that of “Inductive Fallacy”. What resembles (and makes them both “inductive”) is that they are deductively invalid: their form is not that of a valid syllogism.”

Argumentics is in error here. What makes an argument inductive is not being deductively invalid. After all, affirming the consequent is an invalid argument but is not classified as an inductive argument.

While inductive arguments are all technically invalid (since an inductive argument can have all true premises and a false conclusion at the same time), they are not intended to be valid and are assessed by different standards.

Turning back to the examples themselves, they are different.

Example of an Inductive Argument
Premise 1: Most American cats are domestic house cats.

Premise 2: Bill is an American cat.

Conclusion: Bill is domestic house cat.

Example of an Inductive Fallacy
Premise 1: Having just arrived in Ohio, I saw a white squirrel.

Conclusion: All Ohio squirrels are white.
(While there are many, many squirrels in Ohio, the white ones are very rare).

The non-fallacious inductive argument is an inductive  syllogism (see comments below)and the specific example is a strong argument. After all, if it is true (which it is) that most American cats are domestic house cats and Bill is an American cat, it is very likely that Bill is a domestic house cat. In short, the truth of the premises makes the conclusion likely to be true and this makes the argument strong.

In the example of the fallacy, the inference is from one example (the white squirrel) to all Ohio squirrels. The truth of the first premise does not make the conclusion likely to be true, hence the reasoning is poor. It is, in fact, a classic example of a hasty generalization.

Argumentics also brings up a not uncommon comment, namely that my examples are not really arguments. For example, s/he asserts that the following is not an argument: “Equal rights for women? Yeah, I’ll support that when they start paying for dinner and taking out the trash! Hah hah! Fetch me another brewski, Mildred.”

Argumentics does raise a reasonable concern here. After all, the imaginary person does not clearly identify his premises or conclusion and could be taken as merely saying stuff rather than as committing an error in reasoning. As such, it would seem to be something of a leap to take this as a fallacy and also it could be contended that I should have provided an example with a clear conclusion and clear premises. For example, a “complete” example would look something like this:

Premise 1: I have mocked the idea of equal rights.
Conclusion: Therefore, women should not have equal rights.

However, the reason why I used the original example is that when people engage in fallacious reasoning in “real life”, they typically do so in a very rough and informal manner. In fact, sometimes it is so rough and informal that it might be a matter of reasonable dispute as to whether or not the person is actually even arguing. However, in the example I gave, the person seems to intend to reject the notion of equal rights for women on the basis of his making fun of the idea, which seems to be an appeal to ridicule.

I am willing to admit that this is a reasonable point of concern and is, in fact, one my students raise: how do we distinguish between a fallacy and someone merely saying things that sort of look like a fallacy (the same applies to non-fallacious arguments)? In some cases, we can clearly tell. In other cases, it can be a matter of judgment. What, I think, is important is being able to tell when good reasoning is absent-either because a fallacy is being committed or because reasoning turns out to be absent altogether.  At a later date, I should write more about this.

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31 Comments.

  1. I’m not sure I agree with the restatement of the equal rights argument you present. A (too?) charitable re-reading of it might be this:

    1. Women aren’t expected to pay for dinner when out with a man
    2. Women aren’t expected to take out the trash
    3. To have equal rights is to be expected to do all the same things as a man

    Therefore,

    4. Women should not have equal rights unless they can be expected to do all of the same things men are expected to do

    They may also be a suppressed premise about women not wanting to pay for dinner or take out the trash, but I don’t think it’s necessary for the argument to work.

    I should point out that all three of the premises seem clearly false to me, but I can at least understand why someone would use them.

    But I’m also guessing I might be too charitable because the person making that statement is either a) aiming for laughs and not truth or b)quite hateful of women.

    Thanks for posting the PDF of 42 Fallacies. It’s quite useful…it would be fun to run through it in a Critical Thinking course.

  2. Mike –

    Thanks for the pdf. In this post, you write:

    “Example of an Inductive Argument
    Premise 1: Most American cats are domestic house cats.
    Premise 2: Bill is an American cat.
    Conclusion: Bill is domestic house cat.”

    and then
    “The non-fallacious inductive argument is an inductive generalization”

    This argument is not a generalization–its conclusion is about a specific item, namely Bill.

    Rather than being a generalization, the example you have provided goes by the names “instantiation syllogism” or “quasi-syllogism”. It employs the result of a generalization “Most American cats are domestic house cats.”.

    You might change your example to one with a large, random sample, which will then cleanly contrast with what you call “Inductive Fallacy”.

    Notice also that the fallacy is fallacious even without the knowledge that “(While there are many, many squirrels in Ohio, the white ones are very rare)”. And in general, I don’t find it helpful to use locutions such as “an inductive argument can have all true premises and a false conclusion at the same time”, as if we knew the truth value of the conclusion at the time of the argument’s evaluation. We argue in order to expand our/our audience’s set of beliefs.

    All the best,
    Cathal

  3. Mark, although this time I’ve learned my lesson and I will leave “condescending remarks and personal attacks” aside, I still believe you are making two enormous confusions.

    1. “strength” vs. “reasonableness”

    To put it as roughly as I can: a poor argument is not a fallacy. Not at all and not even close. In fact, the connection between the two is so fragile and possibly misleading, that the first thing you did, in the theoretical preamble, is to separate the ‘error’ from the ‘fallacy’. Now let us see how this reflects on your examples.

    I’m glad we both agree that the arguments are inductive, but we still do not agree upon what is it that makes their “inductiveness”. You write: “What makes an argument inductive is not being deductively invalid. […] they are not intended to be valid and are assessed by different standards.” I agree with both these statements, but I do not agree with your application of them. If neither of the arguments are „intended to be valid”, then their conclusions in fact include a qualifier – like „probably”, or „plausibly”, „in all likelyhood” etc., although the actual inclusion of this qualifier in speech can be ommitted. Fully-fledged, not-deductively-valid versions of the conclusions would then be: „Bill is PROBABLY such-and-such cat” and „All squirrels are PROBABLY such-and-such”. In order for both the speakers and the analyst to „assess by different standards”, as you put it, to change deductive validity for this sort of scalar strength, they both have to recognize such qualifiers.

    But then, if this is the case, then the second argument is fallacious because its weak! You write: „The truth of the first premise does not make the conclusion likely to be true, hence the reasoning is poor. It is, in fact, a classic example of [the fallacy of] hasty generalization.” It is here that you make that enormous confusion and I believe you altered your examples in order for the confusion to pass unnoticed.

    What you said about the fallacious argument, „the truth of the first premise does not make the conclusion likely to be true”, can just as easily be said about your first example IF WE CONSIDER JUST THAT. Let’s see the strength of this argument: „Premise 1: Most American cats are domestic house cats. Conclusion: Bill is domestic house cat.”. Maybe Bill is a snake, or a rhynocerous or a door-knob. If we disregard the second premise, nothing tells us that snaky-Bill is not the case. We can get the same „first premise does not make conclusion strong” even if we would consider Premise 2 instead of Premise 1: „Premise 2: Bill is an American cat. Conclusion: Bill is domestic house cat.” Of course, maybe most American cats are anything but house cats. So, considering just the amount of strength the first premise draws on the conclusion, both arguments are fallacious! Bill being a door-knob is just as good a counter-example as an Ohio squirrel being black. I’m sure you got the point, but let me insist. If the truth of the first premise, and the amount of strength it passes on to the conclusion is what makes inductive arguments fallacious, if this is the criterion, then you should not have written “if it is true that most American cats are domestic house cats AND BILL IS AN AMERICAN CAT, it is very likely that Bill is a domestic house cat.”, but „if it is true that most American cats are domestic, it is very likely that Bill is a domestic house cat”. Door-knob-Bill would, in the second case, disagree.

    I have to leave now. When I’ll come back tonight, I will explain your second confusion, the one between „induction” and „generalization”. To give you a hint, let me point out that you say „The non-fallacious inductive argument is an inductive generalization”, so a „generalization” for an argument that passes from „MOST American cats” to „Bill”. I’m sure you see the fishiness of this.

    PS: I’m sorry about the trash-talk in the first post. Since we do not know each other, it was inappropriate, but at the same time, you can be sure it was nothing personal.

  4. 1. OK. So, to summarize: the fallaciousness of the second argument, according to your analysis, is its lack of strength. But I think it’s fair to say that its lack of strength is nothing logical (in the narrow sense, there’s nothing logically impossible with all the squirrels in the world being white, since “This squirrel is white” is not a tautology), but a weakness in the facts. As you say, “the white ones are very rare”. So the guy has it’s facts wrong. This – as you sensibly noted in the theoretical introduction – is not what fallaciousness is.

    Your way to get around this was to alter the examples in various ways so that their differences are more apparent than their basic similarity (that being their non-deductive character, upon which we agreed). The first alteration was inserting the mild quantitative “most” in the non-fallacious one (NF, from now on) and the impertinently inclusive “all” in the fallacious one (F). Your second way to alter them was to (inexplicably, in my opinion) suppress the F’s second premise. I think it’s not a coincidence that in this second premise, the “error” – as opposed to fallaciousness – would have been blatant. “If I see a white squirrels, all squirrels are white” is simply a false (or highly improbable, but not necessarily impossible) statement. Using it will lead to error. The third way to alter this was to not include any qualifiers (e.g. “probably”).

    Returning to the starting point: an error is not a fallacy. The F is the argument of someone being in error (not knowing that “If this than that” is false). The NF is the argument of someone being right about things. However, as regards the NF, state of affairs does not create fallaciousness. If it would, and if NF was wrongly using the “Most these are such-and-such”, it would make it a fallacy also. That is why I said that your examples confuse “strength” and “fallaciousness”.

    2. As regards your notion of induction, the previously announced second confusion, I will take the statement “the non-fallacious inductive argument is an inductive generalization” as a simple blunder. I’m sure you won’t consider the step from “most” to “Bill”a generalization, and from “one squirrel” to “all squirrels” not one.

    3. The question whether the “equal rights example” is an argument or not lays on the way we reconstruct the natural language form and turn it into a more robust, straightforward, premise-conclusion form. Now, I rely my reconstruction on the commitments entailed by the speech acts X (let’s call him X) performs as regards the opinion at issue (say, “Women should be given equal rights”). The rhetorical question is either the act of his positioning (“Equal rights? (Are you mad?)”) or a simple phatic question (“Equal rights? (…is what you are talking about?)”). Interpreted as “positioning”, it is a commissive (committing X to the statement “Women should NOT be give equal rights” or “IT IS NOT THE CASE THAT…”). Interpreted as phatic question, it is an indirect directive (he looks like he’s waiting for an answer, but his not). The second sentence is, quite clearly, also a commissive. In an ironic way – acting as if predicting a future time for changing his commitment, and since that will never happen, at least according to him – the speaker is making the statement with the intention to state his position: “I DO NOT AGREE that …”. This is what I rely my analysis on. What do you rely on, Mike? What if the speaker says: “I was not arguing for “they should not be given equal rights”, I was just telling you I do not support that, and that I think very little of that”, what will you tell him then?

    PS: If you have time, please follow my blog this week. I will give a full account of some other problems your PDF has. I really do believe they are not just trifling matters, and that thinking the subject of fallacy in such way can be seriously unproductive.

  5. Cathal,

    Oh, I do know that the example I gave is an inductive syllogism. Since part of the post was about civil and non-civil criticisms, I intentionally made what would be an obvious “error” so as to see what people would say. Would it be a civil correction (as you so graciously provided) or a venomous carpet bombing, complete with attacks on my intelligence, education, hygiene and choice in beverages?

    I’ve “corrected” my “error” in the post above, with a note to refer to the comments.

    Also, I do know that the fallaciousness of the hasty generalization does not depend on such knowledge. I did not intend for it to be taken as “proof” that the reasoning was fallacious. Rather, I was just remarking about Ohio squirrels. When I was OSU, there were these famous albino squirrels that were considered good luck to see-especially right before tests.

    As far as the remark about inductive arguments being able to have all true premises and a false conclusion, I just note that as a quality they do, in fact, possess. Saying that does not seem to assume that we know the truth value of the conclusion when assessing the argument.

    In any case, thanks for your comment.

  6. Eric,

    It might be the case that I am in error. In cases where people are presenting such a rough and informal (maybe/maybe not) argument, it can be challenging to sort out what is actually going on. On one hand, perhaps the person is intending to make an argument using mockery in place of evidence. On the other hand, perhaps the person is just saying stuff.

  7. Argumentics,

    In the hasty generalization, the error does seem to be one of reasoning. That is, the person would be drawing a conclusion that is not warranted by the size of the sample. As you note, the person is not making a claim that is logically impossible.

    Perhaps what is occurring is that we are operating with different definitions of “fallacy.” In this popular work (aimed at a general audience) I use the term as it is used in critical thinking: an error in reasoning or, a bit more precisely, an argument whose premises fail to warrant the conclusion. In the white squirrel example, the error is in regards to the process of making a generalization, which I take as a mistake in reasoning. Now, if you have a different definition of fallacy, then that would change things.

    Right, an error is not a fallacy. A fallacy is, at least as I see it, a specific error-one of reasoning. In the case of strength, an inductive fallacy can be defined in terms of its lacking adequate strength. That is, the logical connection between the premises and the conclusion is not adequate. Unlike deductive fallacies, whether an inductive argument has hit the fallacy level of weakness can be a matter of some debate. However, there are some very well established informal and inductive fallacies, such as hasty generalization. Again, if you would prefer another term for these fallacies, that is fine. To borrow from Locke’s remarks on personal identity and terms, we just need to be sure we are clear what we mean by our words.

    In the case of the equal rights, I would tend to go by what the person seems to intend to be doing. Such a remark would seem to be rejecting equal rights on the basis of mockery. However, maybe that is not the case. This does show a practical problem-namely how do we sort out what a person is doing. Since the 42 fallacies was first written (back in the 1990s) I did start to rethink the appeal to ridicule-perhaps it might be better classified as a slanter (as Moore & Parker do). In any case, I am open to revising the work.

    In any case, thanks for your comments.

  8. MIke –

    Thanks for the reply.

    I should have made clear that I meant both points in a teaching context (as I presume your pdf hopes to be) –
    that a straightforward case of generalization (from a large, random sample) would serve better to exhibit “Inductive Fallacy” than a quasi-syllogism (indeed, one might replace your current example on the grounds that quasi-syllogism isn’t an induction at all – but that’s another story),

    and,

    that one might avoid saying true premises and false conclusion “at the same time” in case students/readers think that this is a definition of or a necessary condition for ‘being an inductive argument’. I noticed that this locution was causing my students confusion. Specifically, I think the confusion was felt at the simultaneous ideas that ‘the conclusion is well-supported’ and that ‘the conclusion is (or even “could turn out to be”) false’. I would be interested to know if you or others have had anything like this experience.

    One might instead say that the conclusion can “turn out to be” false, to ensure that students realize that this (e.g. the rarity of white squirrels) is *additional* evidence and that the given argument is, as it stands, strong. My preferred locution in class is to note the possibility that there might be another, stronger, argument which contradicts the conclusion, and speak of the ‘total evidence’ rule.

    Regards,
    Cathal

  9. Induction is the only sure way that we can know anything. Deduction is tautalogous and doesn’t show us anything at all.

    Inductive arguments are always correct. I can’t see how the cat example given above, and the other examples, are an appropriate description of induction.

    I think that induction has been misrepresented.

  10. John,

    While I might be misunderstanding your view of deduction, it does seem that deduction can show us many things. I have heard people claim that deduction does not give us new knowledge because the conclusion does not take us beyond the premises. However, it does seem that the conclusion of a deductive argument can show us something we did not know before. To use an analogy, the answer to a calculation does not take us beyond the “premises”, yet the results of a calculation can be quite surprising. Also, certain philosophers such as Descartes would (and did) argue that deduction can lead us to knowledge. Of course, these folks could be dead wrong (and not just dead).

    While I might also be in error about what you take induction to be or what you mean by correct, your claim seems to be mistaken. After all, inductive arguments can be “incorrect” in that they can be weak or fallacious. For example, a hasty generalization is a form of inductive reasoning, yet is not correct reasoning.

    I’m going by the standard definition of induction (the sort used in basic logic and critical thinking books). However, if you are using the term in a different way, then I probably have no real dispute with you.

  11. Cathal,

    Thanks for the clarification.

    It does seem that my use of an inductive syllogism might be creating more confusion than good. When I revise the 42 fallacies I plan to update it quite a bit-the PDF is essentially a minor clean up of the fallacies write ups I did almost two decades ago. Of course, I am not excusing my mistakes as mere youthful indiscretions. :)

    I have found that some people do get confused by the fact that a conclusion can be well supported, yet false (or could be false). The notion of validity also seems to be confusing-people generally want to take validity as meaning the same thing as truth. So, for example, I will have students ask “so, a valid argument is one with true premises, right?” Because of this, I spend a fair amount of time going over the distinction between the truth of premises and the logical relations between them.

  12. Mike,

    I want to use the standard meanings of induction and deduction.

    From there, I can say that the value of deduction is that it can sign-post what we have forgotton or cannot take in in one go. Thus, deduction has a logical basis only in that it is an aid for those individuals who, valiantly enough, suffer from schematic or pictorial impairment. For logical acts are, after all, pattern recognitions in some form.

    A hasty X looks more like a misapplication of X than a limitation of it.

    The outcome of a calculation does not take us beyond the premises, true; although it is the employment of a “deductive” step as the premise for an induction that might surprise us (viz the calculation example), and not any deductive step.

  13. John,

    Interestingly, Plato also seems to take a similar sort of view. The highest level (rational intuition) is above the level that involves the use of hypothesis and symbols.

    I suspect that logicians would take issue with the view that the use of deductive logic is a crutch for those who are impaired. But, I suppose the same could be said about people who need to use formulas to engage in calculations.

    Some authors do take the view that “bad” arguments do not really count as deductive or inductive arguments. For example, I’ve seem some critical thinking books that take the position that all deductive arguments are valid, while the invalid ones are simply not deductive arguments. Presumably the same can be said of inductive arguments. I do not have any deep commitment to the labels, provided that people are clear in what they mean.

  14. Inductive arguments are a fallacy.

  15. How delighted I am to see polite and erudite discourse on what is actually not intellectual nit picking, but a very important topic.

    Now a trained philosopher I am not, to my chagrin, so the use of terms is somewhat strange to me, although I have much to say on topics of philosophy.

    Let me understand the use: By deductive logic, you (philosophers of qualification, and one hopes quality) are stating that the deductive ‘answer’ is intrinsic in the proposition in the same way that x= +- 2 is intrinsic in x squared equals 4?

    In other words, it is merely a different and perhaps more insightful and often useful, but no richer, description (or transform) or restatement of the same proposition? A mere exercise in logic or mathematics?

    Whereas inductive reasoning is the abstraction from the particular to a generalised abstract case, such as

    “I met a black man, and he couldn’t do sums, therefore all black man are innumerate” sort of thing as an example of a truly fallacious argument or “all stones dropped from a given tower fall to earth at very nearly the same speed, so there is a rule governing the rate at which stones fall, that is independent of their weight” as an example of a truly useful one?

    I.e. what you are saying its that deductive arguments are demonstrably true and if they are not, they are flawed deductive arguments, whereas all inductive arguments are unprovable, because they are not logical, but dependent on the consistency with which their predictions are met in the real world?

    I.e. Scientific theorems in the Popperian sense?

    So one might say that a deductive argument is one that implies through rules of logic the conclusion as implicit in the proposition set, whereas an inductive argument works the other way around. By positing the solution, one merely says that at the very best, the proposition set is not inconsistent with it.?

    So an inductive arguments goes like ‘I have never seen any unicorns in London, therefore there are no unicorns in London’

    (over here, squirrels are red, grey and black: we have no white ones, so Unicorns, I suppose, will have to do)

    I am a great fan of information theory.

    By the above a deductive argument adds no information, though it may result in ‘lossless compression’.

    But an inductive argument is in fact a restatement of reality into a hugely compressed form. With a great deal of information potentially lost.

    I.e. F=ma is a restatement of thousands upon thousands of experiments that have been done, and may yet be done, that completely ignores all the local conditions under which they were done, and the exact shape and size of the objects under test..etc etc. We cant say that it is exactly true, merely that in general we have never, allowing for all those local variations found it to be false. So in terms of its compressibility it actually becomes a very useful shorthand way of saying something about reality as we find it.

    And may leads to other propositions that can also be tested..

    I seems me, that we are saying that inductive reasoning is always suspect, but immensely powerful when it turns out to be a fair shorthand way of representing a data set.

    So that the concept of ‘cat’ as an inductive proposition exists only as a pattern matching algorithm in our brains, and does nothing whatever to reproduce the infinite variety of possible cats in in the world, or imaginary ones outside..but does give us an associated suite of suitable responses when dealing with a real life data set that matches our concept of ‘catness’..

    That does cover perhaps David’s point that all inductive arguments are fallacies, in that they simply can never be proved demonstrably true, but that is no bar to their validity, or at least usefulness anymore than ‘I saw a cat’ is inevitable a hugely compressed representation of a data set that in general comprises the experience of ‘catness’ but, due to our shared experience of cats gets the general idea across of what my experience has been.

    A deductive argument is therefore wrong only because of false logic.

    An inductive argument is wrong even if its logic is flawless, if it doesn’t match reality. Because presumably its always incomplete, it’s always a general maxim derived from a particular data set, and the possibility of further data that disproves it existing has to be always considered.

    See my offensively racist example above.

    If that particular black man was indeed the only black man in existence, then the extension from the particular to the general is valid but trivial and adds nothing. It is in fact a deductive argument at that point. If he is not, then it may be deeply flawed. It MAY still be correct. My dog cant do sums, therefore all dogs are innumerate, is perhaps a pretty useful inductive bit of reasoning…

    is that really the nub of the issue? that deductive reasoning assumes the general case, and derives a particular form of the result, whereas inductive reasoning takes the particular and attempts to formulate a general case from it?

    In which case all deductive reasoning is strictly

    IF the general case is true
    THEN the particular case follows,

    whereas the inductive case should be written more as…

    IF these particular cases are truly representative,

    THEN we may formulate the general case as follows…

  16. How delighted I am to see polite and erudite discourse on what is actually not intellectual nit picking, but a very important topic.

    Now a trained philosopher I am not, to my chagrin, so the use of terms is somewhat strange to me, although I have much to say on topics of philosophy

  17. Join the club..:-)

    The problem with trained philosophers, is that they seem to have forgotten how useful and important it is…

    Present company excepted of course ;-)

  18. “How delighted I am to see polite and erudite discourse…”

    Leo,

    In the space of one thread, in your first contributions to this site, you accuse professional philosopher James Garvey of being in need of lessons in critical thinking for not knowing about ‘the evidence for AGW that contradicts the hypothesis’, you suggest JJM (Jmiret) may be ‘trolling’ because she asks you to provide some small shred of said evidence and does not accept that links to random comments in newspaper articles count as such, and you suggest, by way of alluding to a misquotation of the Queen in Hamlet, that I am insincere – ‘protest too much’ – when I point out the dubious connections the scientific failings of the random denialist your wife googled up a video of to ‘support’ your conspiracy theories about anthropogenic global warming (a subject on which you claim to be “neutral”).

    Mike writes, as if he were addressing you personally that “if someone wants his or her criticism to be taken seriously and considered an addition to the conversation, that person should present his/her comments in a suitable way. That is, in a civil manner.” And now you say you are ‘delighted’ to see polite and erudite discourse?

    On the way to Damascus were you?

  19. Some authors do take the view that “bad” arguments do not really count as deductive or inductive arguments. For example, I’ve seem some critical thinking books that take the position that all deductive arguments are valid, while the invalid ones are simply not deductive arguments. Presumably the same can be said of inductive arguments

  20. Mike writes, as if he were addressing you personally that “if someone wants his or her criticism to be taken seriously and considered an addition to the conversation, that person should present his/her comments in a suitable way.

  21. Great website. An inductive argument is wrong even if its logic is flawless, if it doesn’t match reality. Because presumably its always incomplete, it’s always a general maxim derived from a particular data set, and the possibility of further data that disproves it existing has to be always considered.

  22. I liked your book and website :)

  23. It is difficult to differentiate a lie a fallacie, surely the comporatmiento each person finds meaning and an opposite thing to another.

  24. Complete irrelevant question –

    What is the right age to introduce formal Logic principles to children? Thanks and Regards.

  25. There’s no difference between the ‘cat’ example and the ‘squirrel’ example except sample size, none at all. If one is a fallacy, the other is a fallacy- unless somebody wants to put forward a deductively rigorous definition of the sample size you need to make a valid induction.
    That said, of course the cat argument is more cogent- it’s got a much higher chance to be true based on the evidential (inductive) case. But cogency isn’t concerned with fallacy.
    Another example of this same sort of problem is trust. Your mother/wife/friend/whomever says “There’s a cake in the fridge”. You immediately form the belief “There’s a cake in the fridge”. That’s an argument from authority fallacy- you aren’t allowed to do that with deduction. But that doesn’t mean you aren’t allowed to reason that way, that’s what induction is for- an opportunity to reason about things when the conclusion isn’t self-evident from the premises.
    To the question of ‘how can we tell when somebody is committing a fallacy’, it’s not really that tricky- somebody is committing a fallacy when they make a fallacious argument in an attempt to support a deductive conclusion. If they want to say that something is certain because something is likely, (such as in the cat case), that’s a fallacy. If they insert the word ‘probably’ (or the ‘probably’ is implied because you know what they are driving at and aren’t obsessing over fallacies like a first year philosophy student), then there is no fallacy.

    “Strength” of an argument has nothing to do with it’s fallacious nature. A deductive argument does not have strength- it is either valid or invalid. Anything else has a fallacy in it somewhere. Mike seems to be using a more general understanding of the word fallacy, something like “Mistakes you can make which result in a bad argument”. But a fallacy isn’t that (or rather, it isn’t just that). A fallacy is specifically what makes an argument not deductively valid. Outside of deduction there are no fallacies, there is just a sliding scale of cogency.

  26. Venkat,

    That would depend on the kid and the method of introduction. While I am no expert on children and their education, I’d say that they should start with logic at the same time they start learning math. I would start with the simplest logic at first, then build on that. Kids really should be exposed to logic as soon as possible, but in the states the first real exposure is generally in college (if at all).

  27. Es verdad, resulta algo difícil saber cuando realmente se esta diciendo la verdad, es difícil diferenciar la verdad de la mentira, ya que deducir algo simplemente por hacerlo podría provocar que lancemos un juicio, el cual no sabemos si es verdad o no, lo único que resta es creer a ciegas y esperar a ver los frutos. Fruto malo= Mentira… Fruto bueno= Verdad.

  28. True, it is somewhat difficult to know when you really telling the truth, it is difficult to distinguish truth from falsehood, and to deduce something simply because it could cause us to launch a trial, which we do not know if it’s true or not, all remainder is believing blindly and expect to see the fruits. Lie bad fruit … Fruit = good = Truth.

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