Logical Fallacies


Hasty generalization. Making a generalization from a ridiculous small sample. Requires enough empirical evidence to become warranted and convincing.

Relevance fallacy. Argument may be sound but misses the point. Red herring – Diverting the argument to unrelated issues

straw man – Over simplifying one’s argument

ad hominem – Insulting someone’s character

begging the question – Assume the conclusion of an argument, a kind of circular reasoning

non-sequitur – Making jumps in logic

bandwagoning – Asserting that everyone agrees

either/or fallacy – Creating a “false dilemma” in which the situation is oversimplified

card-stacking – Selectively using facts

false equivalence / false analogy – Making false or misleading comparisons

Appeal to the stone  – dismissing a claim as absurd without demonstrating proof for its absurdity.

Appeal to ignorance  – assuming that a claim is true because it has not been or cannot be proven false, or vice versa.

Appeal to common sense – “I cannot imagine how this could be true; therefore, it must be false.”

Argument from repetition (argumentum ad nauseam, argumentum ad infinitum) – signifies that it has been discussed extensively until nobody cares to discuss it anymore; sometimes confused with proof by assertion

Argument from silence (argumentum ex silentio) – where the conclusion is based on the absence of evidence, rather than the existence of evidence.

False compromise, fallacy of the mean – assuming that the compromise between two positions is always correct.

Begging the question (petitio principii) – providing what is essentially the conclusion of the argument as a premise.

Shifting the burden of proof  – I need not prove my claim, you must prove it is false.

Circular reasoning  – when the reasoner begins with what he or she is trying to end up with; sometimes called assuming the conclusion. Circular cause and consequence – where the consequence of the phenomenon is claimed to be its root cause.

Continuum fallacy (fallacy of the beard, line-drawing fallacy, bald man fallacy) – improperly rejecting a claim for being imprecise.

Correlation proves causation (post hoc ergo propter hoc) – a faulty assumption that because there is a correlation between two variables that one caused the other.

Suppressed correlative – where a correlative is redefined so that one alternative is made impossible.

Divine fallacy – arguing that, because something is so incredible, it must be the result of superior, divine, alien or paranormal agency.

Double counting – counting events or occurrences more than once in probabilistic reasoning, which leads to the sum of the probabilities of all cases exceeding unity.

Equivocation – the misleading use of a term with more than one meaning (by glossing over which meaning is intended at a particular time).

Ambiguous middle term – a common ambiguity in syllogisms in which the middle term is equivocated.

Definitional retreat – changing the meaning of a word to deal with an objection raised against the original wording.

Fallacy of accent – a specific type of ambiguity that arises when the meaning of a sentence is changed by placing an unusual prosodic stress, or when, in a written passage, it’s left unclear which word the emphasis was supposed to fall on.

Fallacy of composition – assuming that something true of part of a whole must also be true of the whole.

Fallacy of division – assuming that something true of a thing must also be true of all or some of its parts.

False attribution – an advocate appeals to an irrelevant, unqualified, unidentified, biased or fabricated source in support of an argument.

Fallacy of quoting out of context – refers to the selective excerpting of words from their original context in a way that distorts the source’s intended meaning.

False authority – using an expert of dubious credentials or using only one opinion to sell a product or idea. Related to the appeal to authority fallacy.

False dilemma (false dichotomy, fallacy of bifurcation, black-or-white fallacy) – two alternative statements are held to be the only possible options, when in reality there are more.

False equivalence – describing a situation of logical and apparent equivalence, when in fact there is none.

Fallacy of many questions (complex question, fallacy of presupposition, loaded question, plurium interrogationum) – someone asks a question that presupposes something that has not been proven or accepted by all the people involved. This fallacy is often used rhetorically, so that the question limits direct replies to those that serve the questioner’s agenda.

Causal oversimplification – it is assumed that there is one, simple cause of an outcome when in reality it may have been caused by a number of only jointly sufficient causes.


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The scientific Method

Wed Apr 26 , 2017
(from wikipedia) The scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry is commonly based on empirical or measurable evidence subject to specific principles of reasoning. The Oxford Dictionaries Online define the […]

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