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Rocketboom on Reasoning and Logical Fallacies
Posted: 13 April 2007 06:15 AM   [ Ignore ]
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Check it out.

Not bad! Although it is well to remember that some arguments may be good even though they are not actually [i:ca2c821e3e]logically valid[/i:ca2c821e3e].

:wink:

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Posted: 13 April 2007 06:15 AM   [ Ignore ]   [ # 1 ]
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Rocketboom on Reasoning and Logical Fallacies

Check it out .

Not bad! Although it is well to remember that some arguments may be good even though they are not actually logically valid.

:wink:

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Posted: 13 April 2007 07:02 AM   [ Ignore ]   [ # 2 ]
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Logical validity is a very tight straightjacket. Any argument of the type:

X’s fingerprints on the door
X’s motive
X’s method
X’s lacking alibi
—————-
X did the crime

... is not logically valid. This is nonetheless structurally identical to the way scientists work when they give a so-called “inference to the best explanation”. That explanation is not logically forced by the evidence, but it is the one that seems simplest and most elegant.

Further, it is a good argument to say:

Most scientists who study X believe Y
—————
Y is true

E.g.: most biologists believe in Darwinian evolution, therefore Darwinian evolution is true. (Or, it should be believed true).

But—nota bene!—this is only a form of the fallacious argument of “appeal to the majority” or “appeal to authority”.

This is one reason why I think people who teach classes in critical thinking should go very easy on these supposed fallacies. They are fallacies of logic, not necessarily fallacies of argument.

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Posted: 13 April 2007 04:07 PM   [ Ignore ]   [ # 3 ]
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Your examples are certainly not deductively valid, but how do you define inductive logic, Doug?  It seems that they would fit into that framework.

Occam

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Posted: 13 April 2007 04:27 PM   [ Ignore ]   [ # 4 ]
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[quote author=“Occam”]Your examples are certainly not deductively valid, but how do you define inductive logic, Doug?  It seems that they would fit into that framework.

Good point, and perhaps they would. But my point is rather that the standard fallacies are fallacies of deductive logic, and whatever else one may say about the virtues of induction, it is not deductively valid.

Every swan I have seen up to now has been white
——————————-
Every swan is white

... is not a deductively valid argument. This should be obvious, since there is no contradiction in its being false—e.g., there might be black swans on an undiscovered island somewhere. (As in fact there are black swans).

Fallacies of “appeal to majority” or “appeal to authority” might actually be inductively valid ... depends on whether they have been probabilistically accurate in the past ... !

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Posted: 14 April 2007 12:12 PM   [ Ignore ]   [ # 5 ]
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I think some of the classical critical thinking fallacies have a partial liklihood of truth or of having some degree of truth.  It’s important to recognize their lack of rigorous deductive logic, but that doesn’t mean we should discard them without further consideration. 

Most of science is probabalistic and subject to modification, not given to the certainty of deductive logic, however, if we ignore all of the life experience, we can’t really arrive at many non-obvious conclusions.

Occam

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Posted: 14 April 2007 12:14 PM   [ Ignore ]   [ # 6 ]
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Absolutely.

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Posted: 15 April 2007 09:46 AM   [ Ignore ]   [ # 7 ]
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[quote author=“dougsmith”] But my point is rather that the standard fallacies are fallacies of deductive logic, and whatever else one may say about the virtues of induction, it is not deductively valid.

Every swan I have seen up to now has been white
——————————-
Every swan is white

... is not a deductively valid argument. This should be obvious, since there is no contradiction in its being false—e.g., there might be black swans on an undiscovered island somewhere. (As in fact there are black swans).

(law of non-contradiction?)
Right, induction is the logical move of identity from a paticular to the universal. “I have seen a thousand apples and they were all red (particular examples), therefore, all apples are red” (universal). Same thing as you mentioned about the swans and the discovery of black swans in Australia.

Deduction is the move from a universal to the particular…“All birds have feathers (universal). This creature has feathers, therefore, it is a bird (particular).

Fallacies of “appeal to majority” or “appeal to authority” might actually be inductively valid ... depends on whether they have been probabilistically accurate in the past ... !

Ad populum is invalid. The appeal to authority (ipse dixit) is only invalid when the “authority” in question is not actually an “authority” about the topic in question. Such as, “My friend is a physicist and he says Koi should not be kept in an aquarium but rather outdoors in a pond.”

The title of “physicist” is not a qualification alone to determine how best to care for fish or opine on the aquarium hobby lest they invoke chemistry and biology but yet that is not the primary concern of study for a physicist.

I only used the example of Koi because I was instructed by the “experts” not to keep Koi in a tank yet my Koi are doing just fine nonetheless going on 6 months. So much for my “authorities” both in person and on the net.

Regardless, that is an excellent link and any authority is subject to be challenged given the introduction of new evidence. Gotta luv the ideals of the Enlightenment and free thought.

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Posted: 15 April 2007 10:07 AM   [ Ignore ]   [ # 8 ]
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[quote author=“Occam”]
Most of science is probabalistic and subject to modification

Just to get my two cents in, I’m of the opinion all science hence all knowledge is based on probability and degree of certainty and subject to modification. For those who disagree, I just want to ask, “And what Sir/Madam do you do with new facts?”

not given to the certainty of deductive logic, however, if we ignore all of the life experience, we can’t really arrive at many non-obvious conclusions.
Occam

Inductive logic is antecedent to deductive logic so at the end of the day we must admonish the Socratic disavowel of knowledge I think. Some things “seem” true…....until they are falsified….........which is the process of inductive logic then which a deductive claim is made based on the previous claims or findings…..yet at some point in time those claims may be falsified with further epistemic discovery and technology.

So yeah, it is a matter of how much confidence we can place on a certain claim or theory which is based on the evaluation of the evidence for such claims or theories. But it is a good thing that this is a part of the logical process of the scientific method.

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Posted: 19 November 2010 10:30 AM   [ Ignore ]   [ # 9 ]
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IMO, a big problem is logic teachers (whether as instructors or as writers of books). Telling each other why the other guy is wrong is a lot of fun. There’s also the ‘freak show’ aspect of it: in introductory psychology classes, the section on crazy people is hands down the most popular.

As Dougsmith pointed out, there are (legitimate) arguments from authority as well as (merely fallacious) appeals. The real weakness of arguments from authority is that while they are arguments for believing that X, they are not explanations of X. Fingerprints, broken glass and an empty safe are arguments that there was a thief, but they aren’t explanations of his action.

Another problem in logic classes is that they confuse students on the square of opposition. It’s common to claim that the particular statements (‘Some S is/is not P’) are ‘existence-entailing’ while the universals (‘All/No S is P’) are not. But many particular truths do not entail existence (‘Some wizards are Harry Potter’s enemies’); a little more uncertainly, many universals are at least meant as existence-entailing (‘All samples of carbon have six protons in their atoms’ nuclei’). It would be better to say that existence or non-existence is established distinct from the basic logical statements. This is likely so even in the modern predicate logic, where it is attempted to ‘bake’ existence right into the particular operator (instead of ‘some S’ we have ‘There exists an x such that’)

Chris Kirk

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Posted: 19 November 2010 11:13 AM   [ Ignore ]   [ # 10 ]
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Wow, this is a thread from the ages. I’m almost tempted to ask where you found it, though I already know the answer. LOL

[quibble] I don’t consider “fingerprints/broken glass/empty safe—> thief” to be an argument from authority; rather, it’s a kind of inference to the best explanation. Though you’re right about arguments from authority generally. They (purport to) give a reason to believe X without providing any real understanding of X.[/quibble]

I’m not sure I get the force of your last paragraph. “Some wizards are Harry Potter’s enemies” has to be read with respect to a particular fictional literary context. In that context there exist ...

Similarly “All samples of carbon have six protons”: [I can’t flip the A so you’ll have to take that as read] A(x) if x is a sample of carbon then x has six protons. Conversationally we already know we have x in hand so we don’t need to be reminded of that in the formalism, but it isn’t there to begin with.

Perhaps I’m missing your point.

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Posted: 19 November 2010 04:04 PM   [ Ignore ]   [ # 11 ]
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dougsmith - 19 November 2010 11:13 AM

Wow, this is a thread from the ages. I’m almost tempted to ask where you found it, though I already know the answer. LOL

[quibble] I don’t consider “fingerprints/broken glass/empty safe—> thief” to be an argument from authority; rather, it’s a kind of inference to the best explanation. Though you’re right about arguments from authority generally. They (purport to) give a reason to believe X without providing any real understanding of X.[/quibble]

I’m not sure I get the force of your last paragraph. “Some wizards are Harry Potter’s enemies” has to be read with respect to a particular fictional literary context. In that context there exist ...

Similarly “All samples of carbon have six protons”: [I can’t flip the A so you’ll have to take that as read] A(x) if x is a sample of carbon then x has six protons. Conversationally we already know we have x in hand so we don’t need to be reminded of that in the formalism, but it isn’t there to begin with.

Perhaps I’m missing your point.

and therefore, God exists, no? Kidding. But debates in one of the naturalism threads got me thinking on a related issue: the immunity of an overarching theory to refutation.

I thought the article i’d read was ready to hand, but I’ll have to dig for it. But let this stand as a preliminary: existence entailment isn’t a necessary consequent of distinguishing between universal and particular statements. Theories have universal statements at their core, and since universals are nowadays couched explicitly without an existential quantifier, they *seem* to be immune to observing counterexamples. If I make ‘All water flows downhill’ a core part of my theory, and I (seem to) see some water going uphill, I cannot question the universal. This may be a poor example, but i’m writing quickly and have to be elsewhere soon.

This isn’t directly related to the debate about miracles that Write4U and I have run into; however, there’s troubling issues lurking in the background about uh, ‘overarching’ scientific statements, and changing or jettisoning them. Divorcing universal statements from entailing that their relations really exist *appears* to untie them from the empirical moorings of observation. (Never mind what it means for putative miracles; maybe sometime you and I could discuss Hume’s argument against miracles from chapter X of his Inquiry. You go first and state his case, or the modern version of it.)

Something Lewontin said chilled me, that we *have to* believe in naturalism as a principle. I find that a little scary, downright religious even - unless it only means *within* the natural sciences. But his claim seemed metaphysical, not merely about scientific practice.

Well, this is not very organized. I’d prefer to either divorce *all* statements from existence entailment, or go back to the aristotelian scheme and only do ‘real’ logic upon statements whose existences we already know obtain - as premisses, that is; the whole point of dialectic is to gain conclusions we lack more direct knowledge of.

And so rifling through old topics I happened on this one . . . and now I have to read some papers I have stored on the topic.

Chris Kirk

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Posted: 19 November 2010 06:30 PM   [ Ignore ]   [ # 12 ]
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inthegobi - 19 November 2010 04:04 PM

I thought the article i’d read was ready to hand, but I’ll have to dig for it. But let this stand as a preliminary: existence entailment isn’t a necessary consequent of distinguishing between universal and particular statements. Theories have universal statements at their core, and since universals are nowadays couched explicitly without an existential quantifier, they *seem* to be immune to observing counterexamples. If I make ‘All water flows downhill’ a core part of my theory, and I (seem to) see some water going uphill, I cannot question the universal. This may be a poor example, but i’m writing quickly and have to be elsewhere soon.

This isn’t directly related to the debate about miracles that Write4U and I have run into; however, there’s troubling issues lurking in the background about uh, ‘overarching’ scientific statements, and changing or jettisoning them. Divorcing universal statements from entailing that their relations really exist *appears* to untie them from the empirical moorings of observation. (Never mind what it means for putative miracles; maybe sometime you and I could discuss Hume’s argument against miracles from chapter X of his Inquiry. You go first and state his case, or the modern version of it.)

I’m still not quite getting the problem here. If what you mean is that there could be empty laws of the form [A(x)(y), if x then y], that is, in a universe without x and y, then I suppose you’re right. But so what?

Re. epistemology, the point of careful observation is to discover if we’ve found a universal. That’s not decided by logical form; the [truth/applicability of the] logical form comes after.

inthegobi - 19 November 2010 04:04 PM

Something Lewontin said chilled me, that we *have to* believe in naturalism as a principle. I find that a little scary, downright religious even - unless it only means *within* the natural sciences. But his claim seemed metaphysical, not merely about scientific practice.

I’m not familiar with Lewontin’s claim, so can’t speak to it. Perhaps what he means is that we have to assume things occur for reasons.

inthegobi - 19 November 2010 04:04 PM

Well, this is not very organized. I’d prefer to either divorce *all* statements from existence entailment, or go back to the aristotelian scheme and only do ‘real’ logic upon statements whose existences we already know obtain - as premisses, that is; the whole point of dialectic is to gain conclusions we lack more direct knowledge of.

And also I’m not familiar with the Aristotelian program you suggest. Seems to me that all logic, by definition, is in the form of a hypothetical. “If x then y” is the basis of all logic, really. The rest is metaphysics.

Perhaps set theory is metaphysics, then. I’m OK with that.

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Posted: 28 November 2010 02:36 AM   [ Ignore ]   [ # 13 ]
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That text she was reading from in the video is one of the ones I learned from. I assure you the section the chapter on fallacies was concerned mostly on inductive reasoning! Fallacies are referring to rhetorical argument mostly. But they do define real errors in reasoning. The text the girl from the website was reading from was a full general overview of logic. So although it has one small chapter devoted to fallacies, it does not sufficiently go into all the details that other references do.

“The Appeal to Authority” as it is labeled in The Art of Reasoning says,

An authority is someone whose word carries special weight, someone who can speak with authority because of expertise in some area of knowledge such as law, science, or medicine. It is perfectly appropriate to rely on the testimony of authorities if the conditions of credibility are satisfied. If they are not satisfied, however, appealing to authority is fallacious.

[p.118 The Art of Reasoning with Symbolic Logic,Expanded Vers., David Kelly, W.W.Norton & Company, New York: 1990]

It then goes on to explain those conditions. Another book dedicated on fallacies make this a little more clearer by labeling the fallacy, “Irrelevant or Questionable Authority”,

    Irrelevant or Questionable Authority

    Definition:  This fallacy consists in attempting to support a claim by quoting the judgment of one who is not an authority in the field, the judgment of an unidentified authority, or the judgment of an authority who is likely to be significantly biased in some way.

[p.122 Attacking Faulty Reasoning, Second Ed., T. Edward Damer. Emory & Henry College, Wadsworth Publishing Co., Belmont California: 1987]

Likewise, all of the fallacies are given the same attention to such concerns. It is understood that we humans have to tolerate certain types of induction for practical purposes. Our brains are evolved to induce the external environment of the world to feed our body’s cells. If we had to wait until we could deduce certainty about our environment, we wouldn’t have made it as far as we did. But we still have to recognize induction for what it is: uncertain in open domains.

Technically, all the fallacies are true as defined. It doesn’t mean someone calls them appropriately though.

By the way, I highly recommend Attacking Faulty Reasoning to everyone. I think it should be a mandatory read for any educational subject requiring proving a point.

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Posted: 28 November 2010 08:15 PM   [ Ignore ]   [ # 14 ]
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I don’t want to get involved in this latest turn of the thread, but I do have one comment on Inthegobi’s first post.

many universals are at least meant as existence-entailing (‘All samples of carbon have six protons in their atoms’ nuclei’). It would be better to say that existence or non-existence is established distinct from the basic logical statements.

  The parenthetical statement is a tautology by definition.  The different elements are defined by the number of protons (Atomic Number) in their nuclei.  Carbon is defined as having an atomic number of six.  If it had five or seven protons it wouldn’t be carbon, but rather boron or nitrogen.

Occam

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Posted: 27 December 2010 08:21 AM   [ Ignore ]   [ # 15 ]
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Occam noted:
‘The statement [‘carbon atoms have six protons’] is a tautology by definition. . . . Carbon is defined as having an atomic number of six.

Thanks much for catching the mistake: I two-thirds agree.

The statement ‘all samples of carbon etc.’ is *not* existence-entailing. (For suppose the elements were not made up of protons, neutrons and electrons: a sci-fi writer might still make up a physics where carbon atoms have six protons.) Altho’ Occam didn’t say this, that’s where his criticism ends up. I fumbled the example.

Occam also calls it a definition. That’s right too.

But it’s not a tautology. That would be a statement that’s true by its logical form alone. ‘If it’s raining, then it’s raining’ - that’s a tautology; ‘It’s either raining or it’s not raining’ - another one. If you put a foreign word or nonsense syllable in place of ‘raining’, the sentences would still be true. Occam may be thinking that ‘Carbon atoms have six protons’ is the tautology ‘C is C’. However there is different knowledge on each side: I have to know already that there’s carbon and what it is in some manner, and i have to know what protons and atoms are, and even what ‘6’ is.

Thanks for the correction.

Chris Kirk

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