Informal Fallacies
Fallacies of Ambiguity
| Common Name | Technical Name | Short Description |
| Ambiguous grammar | Amphiboly | Ambiguous premise due to poor grammar, often misplaced prepositional phrases. |
| Accent | ||
| Intended tone of voice is uncertain | ||
| Which word to stress is unclear. | ||
| Out of context | ||
| Hypostatization | Treating abstract terms as concrete terms. | |
| Division | Assuming the part has the properties of the whole. | |
| Composition | Assuming the whole must have a certain property because of it's parts. | |
| Equivocation | Using multiple meanings of the same word. | |
| Suppression of the agent | Passive voice used to veil, misplace blame or glory. | |
| Ambiguous collective | "'They' ought to do something about that." |
Fallacies of Presumption
| Common Name | Technical Name | Short Description |
| Overlooking facts | ||
| Sweeping generalization | "They are all like that." | |
| Hasty generalization (converse accident) | My Volkswagen has low maintenance therefore they all do. | |
| False dilemma | (see below) | |
| Evading the facts | ||
| Begging the question | petitio principii | |
| Stating a conclusion as a premise | "It is bad because it is bad." | |
| Circular argument | Extended version of the above. | |
| Subsuming a particular | Forcing a particular to take on all the problems of larger group. | |
| Epithets | Use of strong emotional terms to strengthen a weak point. | |
| Complex question | The question presumes the truth it queries. "Have you stop beating your wife?" | |
| Special pleading | "But this is the exception." | |
| Distorting the Facts | ||
| False or weak analogy | "It tastes like chicken." | |
| False or weak cause | "Killing turkeys causes winter." | |
| post hoc ergo propter hoc | After this, therefore because of this. Arguing from temporal sequence to a causal relationship. |
|
| pre hoc ergo propter hoc | Before this therefore causing this | |
| cum hoc ergo propter hoc | Two things happen at the same time or place, so one is assumed to be the cause of the other | |
| Common Cause Joint Effect |
Two things happen at the same time, so it is assumed that they have a common cause. | |
| Gratuitous Inculpation Spurious Causation |
Attributing an effect to a cause which (who) did not do it. | |
| False Dilemma False Dichotomy |
bifurcation | "Ideas are like a light switch, either totally on (right) or totally off (wrong). |
| Slippery slope | "If you take a teaspoon of cough syrup with alcohol, you will soon become a debauched drunk." | |
| Biased statistics Suppressed evidence |
"90% of all doctors SURVEYED said taking aspirin will make your nose fall off." | |
| Irrelevant thesis | ignoratio elenchi | |
| Red herring | Introducing an irrelevant subject to divert attention | |
| Straw man | Misrepresenting an opposing view so that it is easy to attack. | |
| Fallacy of accident | dicto simpliciter | Assuming that if it is true in the general case it is true in this case. |
| Shifting the burden of proof | You are the one who needs to prove me wrong. |
Fallacies of Relevance
| Common Name | Technical Name | Short Description |
| Personal Attack | ad hominem | |
| Genetic fallacy | Attack based on background or origin. | |
| Abusive | Attacking the person rather than the thesis. | |
| Circumstantial | Implying the person has vested interests | |
| You too | Tu Quoque | Saying the person does not act in light of their thesis. |
| Poisoning the well Ridicule |
An attempt to preclude discussion by attacking the opponents credibility. | |
| Group appeal | ad populum | Call to join the larger group and their ideas |
| Appeal to pity | ad misericordiam | Trying to persuade by by arousing pity |
| Appeal to Authority | Merely citing an authority | |
| Unqualified authority | ad verecundiam | |
| Authority of the one | "The teacher says ... ."" | |
| Authority of the many (Bandwagon) | "All my friends are doing it!" | |
| Authority of the select few | "No wise person would ... . | |
| Authority of tradition | "We have always done it this way!" | |
| Appeal to ignorance | ad ignorantiam | Claim of truth due to lack of opposing evidence |
| Appeal to fear (force) | ad baculum | Using threat of force |
| Prejudicial Language | Using words that provide a motive for belief without providing support for that belief. | |
| consequensmacherei | Ascribing to an author thoughts of sentiments which he did not expressly utter in this connection. | |
| Irrelevant thesis | ignoratio elenchi | |
| Red herring | Introducing an irrelevant subject to divert attention | |
| Straw man | Misrepresenting an opposing view so that it is easy to attack. | |
| Fallacy of accident | dicto simpliciter | Assuming if it is true in the general case it is true in this case. |
Miscellaneous Fallacies
| Common Name | Technical Name | Short Description |
| Misleading Vividness | "I saw a plane crash on TV. I will never fly again." | |
| Misuse of averages | "He has one foot in boiling water and the other on dry ice, so on average he is comfortable. | |
| Existential Fallacy | "If I can define it, it must exist." | |
| Attempt to prove a negative | It is very difficult if not impossible to prove that something does NOT exist. |
Some other sites about informal fallacies include:
http://www.nizkor.org/features/fallacies/
http://www.smouse.demon.co.uk/logargnew/logargs.htm
