Logical Fallacy
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List of Formal Logical Fallacies with examples
November 10, 2020 - List of formal fallacies: Affirming the consequent, Fallacy of the undistributed middle, Denying the antecedent, Affirming a disjunct, Denying a conjunct.
deductive argument that is invalid due to faulty reasoning, regardless of the truthiness of the conclusion
Wikipedia
en.wikipedia.org › wiki › Formal_fallacy
Formal fallacy - Wikipedia
2 weeks ago - An error in the sequence will result in a deductive argument that is invalid. The argument itself could have true premises, but still have a false conclusion. Thus, a formal fallacy is a fallacy in which deduction goes wrong, and is no longer a logical process.
What exactly is a formal fallacy?
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January 21, 2025ELI5: Formal and Informal Fallacies
A formal fallacy is an argument where the given information doesn't support the conclusion that is made. An informal fallacy occurs when there is a flaw in the reasoning, but not necessarily with the logic. Examples: Formal Fallacy: If a computer turns on, then it is working. The computer is working. The computer turns on. (The problem with this argument is that some computers will not work, but still turn on. It assumes that the premise is always true. This fallacy is called Affirming the Consequent.) Informal Fallacy: Carbon Dioxide is a gas. Carbon Dioxide is a solid. All gasses are solids. (This is called a hasty generalization, and is a problem with the reasoning, not the logic.) More on reddit.com
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February 27, 2013Formal or Informal Fallacy?
It doesn't matter. You shouldn't waste your time trying to categorize fallacies or give them names or anything like this. Your life will be better if you just ignore all of this stuff. Don't get sucked down the fallacy rabbit hole. There's nothing good down there.
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February 1, 2015Are informal fallacies pointed out too broadly?
I have been preparing for this moment for more than a year . More on reddit.com
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October 10, 2014Videos
07:05
Logical Fallacies Part 1: Formal and Informal Fallacies - YouTube
Learn Logic: Formal and Informal Fallacies [SUB ESP]
Formal and Informal Fallacies - YouTube
Formal Fallacies, an intro to formal logic
07:05
CRITICAL THINKING - Fallacies: Formal and Informal Fallacies - YouTube
Lumen Learning
courses.lumenlearning.com › publicspeakingprinciples › chapter › chapter-6-formal-fallacies
Formal Fallacies | Principles of Public Speaking
Without thinking too hard you can probably think of one counter-example. Let’s try one more: Some doctors are not MDs. Therefore, some MDs are not doctors. While the first premise is true (there are other types of doctors), the second is clearly not true. ... Chapter 6 Formal Fallacies.
Quizlet
quizlet.com › 112555813 › chapter-8-formal-fallacies-and-fallacies-of-language-flash-cards
Chapter 8 - Formal Fallacies and Fallacies of Language Flashcards | Quizlet
a formal fallacy in which the speaker assumes that two things related to a third thing are otherwise related to each other Structure: All X's are Y's. An F is a Y. Therefore, F is an X. Example: All cats are mammals.
Wikipedia
en.wikipedia.org › wiki › List_of_fallacies
List of fallacies - Wikipedia
3 days ago - A condition X is sufficient for Y if X, by itself, is enough to bring about Y. For example, riding the bus is a sufficient mode of transportation to get to work. But there are other modes of transportation – car, taxi, bicycle, walking – that can be used.
Quizlet
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Logic Quiz #4 Flashcards | Quizlet
Study with Quizlet and memorize flashcards containing terms like What is a Fallacy?, Two examples of Formal Fallacu, What is a formal fallacy? and more.
CliffsNotes
cliffsnotes.com › cliffsnotes › subjects › literature › what-is-formal-fallacy
What is formal fallacy?
Both of these examples start out with statements about "some" girls, not all girls. You could safely assume that Julie might have been born with blue hair and that Amy might have long hair.
Internet Encyclopedia of Philosophy
iep.utm.edu › fallacy
Fallacies | Internet Encyclopedia of Philosophy
See Hasty Generalization or ... for examples. An irrelevant appeal to the motives of the arguer, and supposing that this revelation of their motives will thereby undermine their reasoning. A kind of Ad Hominem Fallacy. ... The councilman’s argument for the new convention center can’t be any good because he stands to gain if it’s built. Formal fallacies ...
Khan Academy
khanacademy.org › partner-content › wi-phi › wiphi-critical-thinking › wiphi-fallacies › v › formal-informal-fallacy
Fallacies: Formal and Informal Fallacies (video)
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Pressbooks
pimaopen.pressbooks.pub › intrologic › chapter › 2-2-logical-fallacies
2.2 Logical Fallacies, Formal and Informal – An Introduction to Logic
In our fallacious version, the second premise affirms the ‘then’ part (consequent) instead of the ‘if’ part (the antecedent). That is the formal error! One way to prove the invalidity of the invalid form is to create a counterexample that produces true premises and a conclusion known to be false. For example:
Quizlet
quizlet.com › 498600158 › logic-chapter-4-informal-fallacies-flash-cards
Logic, Chapter 4: Informal Fallacies Flashcards | Quizlet
A formal fallacy is: This is an example: All beagles are dogs. (T) All poodles are dogs. (T) Therefore, all beagles are poodles.
Logical Fallacies
logicalfallacies.org
Logical Fallacies - List of Logical Fallacies with Examples
A comprehensive list of logical fallacies with definitions and examples. Learn to identify formal and informal fallacies in arguments.
Britannica
britannica.com › philosophy & religion › philosophical issues
formal and informal fallacy summary | Britannica
There are many kinds of informal fallacy; examples include argumentum ad hominem (“argument against the man”), which consists of attacking the arguer instead of his argument; the fallacy of false cause, which consists of arguing from the premise that one event precedes another to the conclusion that the first event is the cause of the second; the fallacy of composition, which consists of arguing from the premise that a part of a thing has a certain property to the conclusion that the thing itself has that property; and the fallacy of equivocation, which consists of arguing from a premise in which a term is used in one sense to a conclusion in which the term is used in another sense.
Amateur Logician
amateurlogician.com › home › formal fallacies
Formal Fallacies - Amateur Logician
April 25, 2024 - If P were a necessary condition for Q, then Q could not occur without P. Confusing sufficient and necessary conditions produces this fallacy. Q can be the case without P being the case.
Quizlet
quizlet.com › 286303381 › formal-fallacies-flash-cards
Formal fallacies Flashcards | Quizlet
(Latin for "it does not follow"), in formal logic, is an invalid argument. -In a non sequitur, the conclusion is either true or false, but the argument nonetheless asserts the conclusion to be true and is thus fallacious.
QuillBot
quillbot.com › home › formal and informal fallacies
Formal and Informal Fallacies
May 9, 2022 - Most formal fallacies are errors of logic: the conclusion doesn’t really “follow from” (is not supported by) the premises. Either the premises are untrue or the argument is invalid. Below is an example of an invalid deductive argument.
Reddit
reddit.com › r/askphilosophy › what exactly is a formal fallacy?
r/askphilosophy on Reddit: What exactly is a formal fallacy?
January 21, 2025 -
According to textbooks and Wikipedia, a formal fallacy is a argument that is rendered invalid by a flaw in its logical form, aka an argument where you can tell it is invalid just by looking at its form (hence the word formal) and not content. However, how can these so called logical fallacies like "denying the antecedent" be invalid just by looking at the form, when there are obviously cases like that that are deductively valid? Here are some examples I came up with:
(R->R), ~R, ∴～R (P=Q)
((R v S)->S), ~(R v S), ∴～S (~P entails ~Q alone)
(R->(S & ~S)), ~R, ∴~(S & ~S) (Q is a contradiction)
All these forms are cases of "denying the antecedent" but are obviously deductively valid, in the sense that if the premises are true, the conclusion must be true. Then, only SOME arguments like "denying the antecedent" that are "formally invalid" are actually invalid, not ALL. And so, knowing an argument is formally invalid does not really tell us whether it is valid or not, which does not help at all. Therefore, I think there actually cannot be such thing as a formal fallacy.
(well, I guess there IS one form of argument that can be said to be formally invalid, and that would be an argument where all premises are logical tautologies and the conclusion is a logical contradiction...but no one who discusses formal fallacies ever talks about this, so)
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Here's an argument: All men are mortal. Socrates is a man. Therefore Socrates is mortal Before we formalize it, it sure looks valid in natural language, and it's a standard example given around the world of a valid argument. So let's formalize it in propositional logic. A B Therefore C That's formally invalid. Is this the kind of example you're thinking of? If so, formal validity and invalidity are dependent on the formal system being used. It's formally invalid in propositional logic and formally valid in quantificational logic. If we used propositional logic to formalize it, we wouldn't say "it has an invalid argument form", we'd say "it has an invalid argument form in propositional logic", and since it appears pretty clearly to be valid in natural language, we'd take that as a reason to formalize it with quantificational logic instead of propositional logic. If the argument used modal concepts and looked invalid in propositional and quantificational logic, the right decision might be to use a modal logic. It seems to me that the problem isn't with the concepts of validity and invalidity, the problem is the choice of which formal system to use when evaluating validity/invalidity. This raises some big questions, like how to know which formal system to use, whether or not there's such a thing as "one true logic" (and if so, then which one), how best to interpret arguments in natural language, and the relationship between formal systems and natural language in general.
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A formal fallacy or invalid inference is just one for which there exists a model where it is false. Wrt propositional logic, that means an assignment of truth values where the assumptions are true but the conclusion false (Fact: there are exactly 2^n assignments of truth values for every set of formulae with n variables). Correspondingly, a formula \phi is a valid inference (or a logical consequence of) a set \Gamma iff this inference is true in every model.
Pressbooks
pimaopen.pressbooks.pub › introphilosophy › chapter › 1-4-fallacies-the-basics
1.4 Fallacies – The Basics – Introduction to Philosophy
1 month ago - Formal fallacies occur in arguments that use bad (invalid) form. The scope of this course does not permit extensive examination of a wide range of argument structures, or forms. So, there will not be extensive consideration of fallacies arising from defective form. We will, none-the-less, look briefly at two examples of formal fallacies; each results from invalid (defective!) use of an argument form that we visited earlier in our examination of the deductive argument types.
Quizlet
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Chapter 8: Formal Fallacies and Fallacies of Language Quiz Flashcards | Quizlet
A fallacy consisting of a conditional claim as one premise, a claim that denies the antecedent of the conditional as a second premise, and a claim that denies the consequent of the conditional as the conclusion.
Quizlet
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Logical Fallacies Flashcards | Quizlet
The Fallacy of Relevenceconclusion could not be false but the premises could beBegging the Questiona rational person wouldn't believe the premises unless they already believed the conclusion God e.g.Fallacy of Equivocationtrades on ambiguity, only resolve is to make premise implausible or argument no cogentSlippery Slopesequence of premises, first premise seems innocent and others are conditional (operator if...then), premises together entail a false conclusion.