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Thanks to everyone who responded to my proposal for a logic series!

I welcome any input about what times & days would be best to post the installments. Right now, I'm thinking Monday, Wednesday, & Friday afternoons or evenings, though as more complex subjects come up — or other business unexpectedly eats my time — I may subtract, add, or shift days "sideways" a bit.

At any rate — following the order in my notebook — I'll begin the 1st of several discussions of informal fallacies past the Kos Wingding.

Last time, in my "sample lesson", I gave the basic definitions of propositions & arguments. Here they are again [UPDATE: Definition of "proposition" simplified per suggestion from commenter ends with space]:

A proposition is a statement that may be either true or false.
An argument is a group of propositions that may be either valid or invalid. An argument typically has premises & a conclusion.
(Feel free to review the above link to the diary if you need examples & further explanation.)

Today I will begin the 1st of a series of diaries on informal fallacies.

Basically a fallacy is any kind of mistake in logic. Mind you, nobody has ever made a complete list of all possible ways that someone can think wrongly, so only so much listing & classifying of fallacies can be done. None the less, logicians generally divide fallacies into formal, those which make mistakes in terms of truth & falsehood of propositions, usually through invalid argument forms, & informal, those mistakes that arise from unclear language (ambiguity) or language that's beside the point (relevance).

This diary will focus on several fallacies of ambiguity. (I'll include some of their alternative names so as to help you research these on your own. I prefer to use everyday English forms that I find easy to remember & relay to others, but many textbooks traditionally use Latin & Greek names or potentially obscure technical terms.)

Emphatic Ambiguity (Accent).
Many mistakes can result from placing stress on the wrong part of a statement, or for that matter leaving the appropriate stress unclear. This is especially true for members of an online community, since they cannot see each others' facial expressions or hear each others' voices giving the precise intonation that shows that this is the proper sense which was meant. (An old example: Think how the saying "Woman — without her, man would have nothing!" looks without punctuation.)

Grammatical Ambiguity (Amphiboly).
Sometimes the way a particular statement is phrased makes its precise meaning difficult to figure. (Shakespeare readers will remember "No man of woman born shall harm Macbeth" — & Greek historian Herodotus relays this from the Oracle at Delphi: "If Croesus attacks the Persians, he will destroy a great empire." (If only he knew which one...) Also, what does someone mean who says "I hope this diary gets precisely the attention it deserves"?)

Lexical Ambiguity (Equivocation).
Certain words, whether due to being homophones or having more than 1 popular meaning, can be confusing as well. (Classic humorous illustration: "Some cats chase bugs. My cat chases bugs. Therefore, my cat is some cat!)

Well, I think that will do for now. Please feel free to ask questions in the comments, & I (or other commenters) will try to answer them. Also, I'd welcome any helpful contributions or suggestions.

9:59 PM PT: UPDATE: Definition of "proposition" simplified per suggestion from commenter ends with space.

Originally posted to Brown Thrasher on Wed Apr 04, 2012 at 02:33 PM PDT.

Also republished by Systems Thinking and Logic and Rhetoric at Daily Kos.

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Comment Preferences

  •  very good (6+ / 0-)

    interesting diary.  look forward to reading more in this series.

  •  Lovely. I see this all the time... The Weakness of (5+ / 0-)

    language and grammar is the inexactness of connotative meanings. There is an self-published author I have read on Nook that constantly does the homophone error. He uses 'here' for 'hear' for example... It takes a a moment to catch it but it never fails to amuse me. If he had an editor they would proof read. Come to think of it I need an editor to proofread.

    Often I notice how in the end I find I actually agree with someone who has made an argument that at first blush pissed me off. The main reason we were at odds is that we misunderstood each other or saw different emphasis on parts of thier written words. Or even more frigging annoying is that they use a term I find perjorative and react to that term ignoring the rest of what they are saying.

    Anyway good diary. Been years since I took logic.

    Proud Slut...Fear is the Mind Killer

    by boophus on Wed Apr 04, 2012 at 03:23:11 PM PDT

    •  Indeed, one of the things about "natural" language (3+ / 0-)
      Recommended by:
      boophus, ranger995, Old Lefty how form definitely does_not_ always follow function.

      Sure, we have declarations, questions, commands, & exclamations — but, that said, questions can be rhetorical, acting like declarations, or they can be polite ways of commanding someone to do something ("Why don't you tell me what's bothering you?"); commands can ask for information in the style of questions, lots of things can turn into exclamations, & so on...

      In logic, & philosophy in general, changing definitions or language-uses in mid-stream is not only bad form, but can_really_ make a mess out of things (& tends to indicate confused thinking at best, or at worst somebody trying to play a rhetorical "shell game" on you.)

      I guess that's why informal logic tends to come 1st in the textbooks — to make sure people get in the habit of stating their ideas clearly & precisely.

      Tell Congress: DON'T BREAK THE INTERNET! Learn about the OPEN Act.

      by Brown Thrasher on Wed Apr 04, 2012 at 07:06:30 PM PDT

      [ Parent ]

  •  Will you eventually be bringing this around to (4+ / 0-)

    how this relates to political rhetoric and messaging?

    Stop the party of Gut & Spend policies that gut our Earned Benefits programs like Social Security and Medicare and spends on deeper and deeper tax breaks for the wealthy elite.

    by jillwklausen on Wed Apr 04, 2012 at 04:53:27 PM PDT

  •  Thanks for following up. (3+ / 0-)
    Recommended by:
    phonegery, Brown Thrasher, linkage

    I look forward to the rest of the series, especially if you get into how it relates to both the internal, kossak-to-kossack arguments, and the external, kossack-to-lying-illogical-winger arguments, with examples.

    Oh, and pardon the preemptive argumentum ad hominem against the wingers. I would argue it has the merit of accuracy ;)

    Tipped and Rec'd.

    The problem with going with your gut as opposed to your head is that the former is so often full of shit. - Randy Chestnut

    by lotusmaglite on Wed Apr 04, 2012 at 05:04:23 PM PDT

    •  I'm glad you're interested! (2+ / 0-)
      Recommended by:
      ranger995, linkage

      Indeed, one could spend a whole diary digging through examples of personal-attack & "genetic" fallacies.

      It'd be great if such a discussion ended up helping to fend off a right-wing sophist or even simmering down a future "pie fight" (though I'll be happy at this stage to get the help of some Kossack logicians, teachers, & debaters to help me work on my own rhetorical skills...).

      Tell Congress: DON'T BREAK THE INTERNET! Learn about the OPEN Act.

      by Brown Thrasher on Wed Apr 04, 2012 at 07:53:55 PM PDT

      [ Parent ]

  •  Reposted to Systems Thinking - N/T (2+ / 0-)
    Recommended by:
    Brown Thrasher, ranger995

    "Upward, not Northward" - Flatland, by EA Abbott

    by linkage on Wed Apr 04, 2012 at 05:51:37 PM PDT

  •  Philosophy, ESPECIALLY Logic, has always (2+ / 0-)
    Recommended by:
    Brown Thrasher, linkage

    escaped me, but then it was never presented quite as clearly -- or simply (and this is a good thing) -- as this.  Thanks, BT.  Tipped and recced (and when you get to political rhetoric and messaging, there's a new group that will republish this).

    All it takes is security in your own civil rights to make you complacent.

    by Dave in Northridge on Wed Apr 04, 2012 at 07:02:07 PM PDT

  •  Request for clarification (2+ / 0-)
    Recommended by:
    Brown Thrasher, linkage

    I'd like to share my reactions to this diary and the proposed series in order to understand the goal. My confusion is this: I feel like you're conflating two topics that aren't as closely connected as most people think.

    The first of these topics is actual mathematical logic. That's where you seemed headed with your definition of "proposition". We'd continue with truth functions, syllogisms, and the rest of propositional logic, then leap to predicate calculus, and onward. It would be interesting to see how far you could go while targeting a lay audience. (Full disclosure: My own field is computational logic, unlikely to be interesting here.)

    The second topic is what we might call "rhetoric" or "argumentation" or even just "debate": Being aware of fallacies and flaws in arguments or information presented to you, how people manipulate your emotions rather than your reason, the nature of "proof" in nonmathematical reasoning (and the unacceptable substitutions for proof frequently encountered) and so forth. You start to tackle this in your treatment of ambiguity.

    This second topic is IMHO more important in political settings, and certainly seems to be what people are eager for, based on the comments. I myself think that studying "real" logic isn't all that relevant. The syllogism "Some men are Greeks, Aristotle is a man, therefore Aristotle is a Greek" is invalid, but understanding exactly why and learning about implication and quantification and Venn diagrams doesn't help much in understanding political discourse, because this isn't typically the sort of invalidity we need to learn to cope with and be on guard against (though the terminology can be helpful). And yet I always run across the sentiment that somehow studying formal logic will improve our debating skills. The skills we really need are much harder.

    I'd be interested to hear your reaction to my point of view and your intent for the series. Possibly you disagree with me entirely, or possibly you just mean to use the word "logic" in a more informal sense, as when you distinguish between formal and informal fallacy.

    If you do intend to cover formal logic, then certainly I'm in 100%, and I'll try not to be overly pedantic in commenting on the material. But as long as I'm writing: Your definition of "proposition" makes me uneasy. I don't think a proposition needs to be "falsifiable" or "factual" and certainly not "about reality". I'd say it like this: a proposition is a sequence of words to which we can assign a truth value, either "true" or "false". This is purely a grammatical concept and has nothing to do with the real world, which might or might not be the determiner of whether "true" or "false" is the correct truth value. "Snow is white" is a proposition, as are "I journeyed hither a Boeotian road" and "There is no God but Allah" and "A scout is reverent" and "x equals 3". Non-propositions include "love" and "running quickly" and "Where are you?" and "Damn it!", because these don't admit of being designated "true" or "false". "Thoughts fly far", to take your example, is certainly a proposition, since it has the correct grammatical form---it can be labelled either true or false, though we might disagree on which is correct.

    I suppose that there's no longer any question about the falsehood of the proposition "Ends With Space is not going to be pedantic".

    Anyway, I look forward to the series.

    •  Thanks for your input. (0+ / 0-)

      I was certainly hoping to get some critical comments to help my presentation (& yes, some degree of pedantry is called for here).

      Since I'm planning on referring to previous diaries as the series develops, I will definitely update (or completely revise & re-diary?) the inaugural "lesson" to correct any hastily-written inaccuracies such as those you mention. (& yes, upon reflection, my definition indeed sounded more like an attempt to describe a scientific hypothesis than the much simpler concept of a proposition).

      As for the overall purpose of the series, political applications definitely constitute one of the driving points — though one can certainly take the raw basics of this subject many different directions, & in that sense I think I'd err if I confined the import of the early definitions too quickly.

      Tell Congress: DON'T BREAK THE INTERNET! Learn about the OPEN Act.

      by Brown Thrasher on Wed Apr 04, 2012 at 09:35:09 PM PDT

      [ Parent ]

  •  Oh, I thought this was gonna be about Ps and Qs (2+ / 0-)
    Recommended by:
    Brown Thrasher, linkage

    as in

    If P then Q

    "If you don't sin, then Jesus died for nothing!" (on a sign at a Mardi Gras parade in New Orleans)

    by ranger995 on Wed Apr 04, 2012 at 08:48:19 PM PDT

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