It might seem like I’m doing a terrible job of keeping my promises about what posts will be coming.  After all, you were supposed to get a review for The Golden Verses of Pythagoras last week, and instead you got a peculiar review for a trio of short stories.  You were also promised a post on logical fallacies following the review for The Art of Thinking Clearly, but ended up with a post on linguistics, instead.  However, I do eventually get around to keeping my promises, and compared to a few other examples on the site, this one is happening relatively quickly.

Unlike in The Art of Thinking Clearly, which never bothered to define what a logical fallacy actually is before proceeding to list more than ninety of them, or at least what the author claimed were fallacies, we will begin with a definition.  The precise definition might vary a little from person to person, or depending upon the context, but this is mine.  A logical fallacy is a systemic flaw in the sequential process of deriving conclusions that can occur in any application of that method of deliberation, and can result in achieving erroneous end states.  Significantly, it does not include cases of failure to implement logical processes in the first place, nor does it apply in most cases to innate traits of neurophysiology.

If that definition seems a little complicated, don’t worry: I’ll be explaining the definition and its components in excruciating detail before proceeding with the identification of my significantly shorter list of “true” logical fallacies.  Also, I do realize the irony of spending a preponderance of this post on a custom definition after railing against just that in books like Justice as Fairness in last week’s post.  In my defense, this effort has more to do with refining a definition and applying it than it does with a genuine redefinition.

Our first task should be to define the terms that we are attempting to define: logical fallacy.  Logic is a way of thinking in which each successive conclusion is based upon those preceding.  A fallacy being a way in which something does not perform its intended function, a logical fallacy can be more simply defined as a case in which the application of the mode of thinking characterized by sequential concluding arrives at an erroneous result.  However, I do not like the term “case” in this application, because a logical fallacy should reflect something more fundamental about the mode of thought in question; it should reflect a systematic flaw by which the application of sound logic fails to lead to a valid conclusion.

Therefore, I instead assert that a logical fallacy is a systemic flaw in the sequential process of deriving conclusions that can occur in any application of that method of deliberation, and can result in achieving erroneous end states.  It is the systemic element that primarily separates my definition from the one implicit in the list of “fallacies” provided in The Art of Thinking Clearly.  A logical fallacy is not merely a case of logic being misapplied, or not applied at all, but a case where the discipline of logic is applied and supports an invalid conclusion.  These are not tendencies, effects, or similar, neurophysiological interferences with the functioning of logic, but actual problems with the application of logic itself.

My list of logical fallacies includes:

  1. Slippery Slope Fallacy: in which an application of logic leads to an irrationally extreme conclusion
  2. Coincidence Fallacy: in which causation and correlation are confused at some point in the logical process
  3. Certitude Fallacy: in which a conclusion is reached based on an intermediate step which is treated as more factual than it might actually be
  4. Sunk Cost Fallacy: in which continued investment is justified by past investment
  5. Confidence Fallacy: in which greater credence is lent to conclusions derived by native logic than conclusions derived by external logic
  6. Hindsight Fallacy: in which a result is framed as logical/inevitable after it has occurred, even if that result would have been neither beforehand
  7. Exceptions Fallacy: in which an application of logic justifies an exception to previous logic
  8. Occam’s Razor Fallacy: in which proper application of Occam’s Razor leads to hasty conclusions and unsupported determinations of causation and correlation
  9. Correlation Fallacy: in which two or more data points are considered related with insufficient supporting evidence
  10. Causation Fallacy: in which causation is inappropriately inferred based on correlation or application of pure logic, such as Occam’s Razor
  11. Insular Fallacy: in which a conclusion is reached based purely on logic and inference, without incorporating evidence
  12. Breadth Fallacy: in which logic reached an incorrect conclusion by being applied through a limited dataset or knowledge base (“when you have a hammer, everything’s a nail”)
  13. Detail Fallacy: in which one of two logical conclusions is treated as more valid based on being presented in greater detail (related to the Confidence Fallacy)
  14. Justification Fallacy: in which logic is applied to explain an illogical action, event, result, or occurrence
  15. Rational Actor Fallacy: in which logic fails to account for its own absence
  16. Applicability Fallacy: in which logic as a mental tool is applied in situations in which that mode of thinking is inappropriate or inadequate – a circumstance in which it is not acknowledged that the universe is not bound to be logical
  17. Reasonableness Fallacy: in which a logical conclusion is reached and accepted or rejected based on its apparent “reasonableness”
  18. Alien Fallacy: in which logic is applied to a completely unfamiliar circumstance upon which the thinker has insufficient information to support any step in the sequential process of conclusion
  19. Discontinuity Fallacy: in which trends are followed without consideration for potential deviations from trend that are not reflected in the available data

This is not intended to be an exhaustive list, nor is it presented in any particular order.  You’ll notice that it is much shorter than the list presented in The Art of Thinking Clearly; recall that I am asserting that only actual problems with logic itself can qualify as logical fallacies, not other mental habits, processes, or lack thereof that can lead to logic being misapplied or not applied at all.  Even some of those listed here could be considered on the line between applying specifically to logic, and applying to a larger sense of cognition.  What can be said of this list is that these are factors that I attempt to consider when I am applying logic.

Of the nineteen fallacies presented, I consider Slippery Slope, Coincidence, Sunk Cost, Exceptions, Correlation, and Causation to be the most prevalent, pernicious, and deleterious.  We’ve posted before about Slippery Slope and Exceptions, and I think Sunk Cost is relatively clear, but I intend to dedicate an entire post in the near future to discussion coincidence, correlation, and causation, both as logical fallacies and in a larger sense.  So you have that to eagerly anticipate.  Just don’t necessarily expect it to be next Tuesday’s post.

Where I do agree with Dobelli is that it is probably impossible to complete expunge from our thinking all of these fallacies, whether my list or his (although some of Benjamin Franklin‘s techniques might help).  Especially in the case of the innate tendencies, habits, and products of our native neurophysiology and the basic functioning of our brains and bodies the best we can hope to do is be sufficiently aware of them that we can identify and correct when we are being misled when it is most important.  With logical fallacies like those in my list, we can work to expunge them from our thinking with deliberate practice, training, and attention, but even then we are still apt to make mistakes and apply logic in such a way that it leads us into a fallacy.  Bluntly, logic is an imperfect tool with which to understand the universe, and there is only so much that can be done to hone it.

That is not an excuse, however, to forgo logic entirely, as it is a wonderfully useful tool of cognition under a wide variety of circumstances.  I think of it almost as compromise between intuition (or instinct, if you prefer, but that opens up a whole different conversation about the nature of instinct) and the scientific method.  Logic is slower, but more accurate, than intuition, while being faster, but less accurate, than the scientific method, which is why, despite its fallacies and shortcomings, I still advocate for the application of and training in logic as a cognitive technique.  What becomes dangerous is treating it as the only technique, or worse, as a final statement of judgement upon a subject.

Crucially, logic is not about building a winning argument.  There are techniques for crafting winning arguments, and while they might share certain traits in common with logic, they are distinct from that cognitive process.  Conflating the two is dangerous, and why even the most academic and rigorous of debates can fail to inform or even be productive on the issue.  Aristotle was writing about rhetoric, not about logic, however much there might be superficial similarities.

For all of its flaws, as demonstrated by the list of fallacies above, logic is a powerful tool with which to approach problems, and especially so when applied in conjunction with other tools and with awareness of the fallacies that could hamper its operation.  Yes, it can be used to justify almost anything, but it can also be a way to quickly and rationally approach problems, situations, and discussions in a way that is far more rigorous than the proverbially gut check.  To conclude, well, there’s really only one viable way to end a post about logical fallacies: live long, and prosper.

2 thoughts on “Logical Fallacies

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