Formal and Informal Fallacies

Logical Fallacies are commonly divided into formal and informal. Formal fallacies occuring in Syllogisms are called Syllogistic fallacies.

  • A valid argument has a correct formal structure. A valid argument is one where if the premises are true, the conclusion must be true.
  • A sound argument is a formally correct argument that also contains true premises.

Ideally, the best kind of formal argument is a sound, valid argument. Formal logic is not used to determine whether or not an argument is true, they do not take into account the soundness of an argument, but rather its validity.

Informal fallacies - arguments that are logically unsound for lack of well-grounded premises.

The use of fallacies as rhetorical devices is prevalent when the orator’s goal is eliciting common agreement rather than correctness of the reasoning. The argument should be recognized as unsound and the conclusion regarded as unproven.

There are only Informal Fallacies in this list.

Improper Premise Fallacies

Also called Question-begging fallacies. A false premise is an incorrect proposition that forms the basis of an argument or syllogism. Since the premise (proposition, or assumption) is not correct, the conclusion drawn may be in error. However, the logical validity of an argument is a function of its internal consistency, not the truth value of its premises.

Fallacy Other names and comments
Circular Reasoning circulus in probando, circular logic reasoner begins with what they are trying to end with
Begging the Question petitio principii, type of Circular Reasoning, argument’s premises assume the truth of the conclusion, instead of supporting it
Loaded Language using language and phrases with strong connotations to invoke an emotional response and/or exploit stereotypes
Loaded Question plurium interrogationum, fallacy of many questions, fallacy of presuppositions
No true Scotsman appeal to purity

Faulty generalizations

Faulty generalization – reach a conclusion from weak premises. Unlike fallacies of relevance, in fallacies of defective induction, the premises are related to the conclusions yet only weakly support the conclusions. A faulty generalization is thus produced.

Fallacy Other names and comments
No true Scotsman Accident
Survivorship Bias Cherry-Picking Fallacy
False Analogy argument by analogy, faulty analogy
Hasty Generalization jumping to conclusions, secundum quid, fallacy of insufficient statistics, hasty induction
Inductive fallacy Conclusion is made of premises that lightly support it. Close to Hasty generalization
Misleading Vividness Going deep into details to exaggerate importance. Close to Appeal to Emotion
Overwhelming Exception Proviging to many opposing facts to lower impression from initial statement
Thought-terminating cliché Phrase to end the debate with a cliché rather than a point.

Questionable cause

This group of logical fallacies is described by first - “Cum hoc ergo propter hoc” and has 3 subgroups.

is either inappropriate deduction (or rejection) of causation or a broader failure to properly investigate the cause of an observed effect.

Fallacy Other names and comments
Cum hoc ergo propter hoc Correlation without but implies causation - two non-related events correlate by coincidence
Post hoc ergo propter hoc False Cause - after this, therefore because of this
Wrong direction Reverse causation - the consequence of the phenomenon is claimed to be its root cause
Ignoring a common cause Spurious relationship is confused for causation
Gamblers fallacy Monte Carlo fallacy - if an event occured more frequently than normal in the past it is less likely to happen in the future
Inverse gambler’s fallacy unlikely outcome of an event, if this event has occurred many times before.
Single Cause Fallacy Complex cause, reduction fallacy, Causal Oversimplification - there is a single, cause of an outcome
Furtive fallacy Outcomes are asserted to have been caused by the wrongdoing by decision makers
Magical thinking Claming of causal relationships between actions and events
Regression fallacy The flaw is failing to account for natural fluctuations

Relevance fallacies

These are distractions from the argument typically with some distracting sentiment that seems to be relevant but isn’t really on-topic.

Fallacy Other names and comments
Appeal to the stone argumentum ad lapidem- dismissing a claim as absurd without demonstrating proof for its absurdity
Argument from ignorance appeal to ignorance, argumentum ad ignorantiam - claim is true because it has not been proven false
Argument from incredulity appeal to common sense - We cannot imagine how this could be true. It must be false
Argument from repetition argumentum ad nauseam, argumentum ad infinitum - repeating an argument until noone discusses it any more (vs proof by assertion)
Argument from silence argumentum ex silentio - claim is true because no any evidence from an authoritative source
Ignoratio elenchi irrelevant conclusion, missing the point - argument not addressing the issue in question

Red Herring fallacies

Red Herring are a specific sub-class of Fallacies of Relevance that is distinguished by specific intent to mislead and detracto from the main factual point of discussion. Red Herring Appeals group:

Fallacy Other names, sub-classes and descriptions
Ad Hominem Circumstantial ad hominem / Appeal to motive, Poisoning the well, Kafka-trapping, Tone policing, Traitorous critic fallacy
Tu Quoque appeal to hypocrisy, whataboutism - part of Ad Hominem fallacies group
Name Calling Simplified argumentum ad personam (Personal Attack)
Appeal to Authority argument from authority, argumentum ad verecundiam - not proofing argument but citing a expert’s opinion
Appeal to accomplishment it is true because of the accomplishments of the proposer.
Appeal to consequences argumentum ad consequentiam - it is true otherwise consequences would be bad
Appeal to Emotions Appeal to fear, Appeal to flattery, Appeal to pity, Appeal to ridicule, Appeal to spite, Pooh-pooh, Wishful thinking
Appeal to nature a thing is good because it is natural
Appeal to novelty argumentum novitatis - It’s good because it is new
Appeal to poverty argumentum ad Lazarum - it is true because the arguer is poor (or it is false because the arguer is wealthy).
Appeal to Tradition argumentum ad antiquitatem - it is right because it has been like this for a long time
Appeal to wealth argumentum ad crumenam - it is true because the arguer is wealthy (or it is false because the arguer is poor)
Argumentum ad baculum appeal to the stick, appeal to force, appeal to threat - if you do not agree I can force you to
Argumentum ad populum appeal to the majority,appeal to widespread belief, bandwagon argument - it is true because many people think so
Association fallacy things are the same because they share some property

Other Red Herring Fallacies

Fallacy Other names, sub-classes and descriptions
Courtier’s reply criticism is dismissed respondent to criticism claims that the critic lacks sufficient knowledge or training
Association fallacy things are the same because they share some property
Ipse dixit bare assertion fallacy - a claim made as dogmatically true, without any without support
Bulverism psychogenetic fallacy - if the arguer is biased, then the clame itself must also be false. Close to Ad Hominem Circumstantial
Chronological snobbery argument claimed incorrect because was held in the same timeframe with another false statement
Fallacy of relative privation not as bad as,appeal to worse problems, incl. First World problems - dismissing an argument because there are important problems to solve
Genetic fallacy something is true or right because of its origin
I’m entitled to my opinion discrediting all other arguments because of freedom of thought
Moralistic fallacy Inferring factual conclusions from evaluative premises, - It is true because it has to be like this in proper way.
Naturalistic fallacy incl. Is-ought fallacy - inferring evaluative conclusions from purely factual premises
Straw man misrepresenting an opponent’s argument by broadening or narrowing the scope of a premise and refuting a weaker version
Texas sharpshooter fallacy improperly asserting a cause to explain a cluster of data
Two wrongs make a right occurs when it is assumed that if one wrong is committed, another wrong will rectify it
Vacuous truth a claim that is technically true but meaningless

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