Classic Flaws

Flaw types in the LSAT

Misread conditionals

reads the conditionals supplied in the premises incorrectly, the order of the sequence is incorrect

Omitted Options

A logical error in an argument where an author assumes a conclusion by ignoring alternative possibilities, third variables, or competing explanations. (The 3 types are new factor, no relationship and backwards causation)

Whole-to-Part

assumes what is true for a group or a whole must also be true for each individual part or member

Part-to-Whole

assumes that since the factors or details of the parts are true, then it must be true for the whole

Overgeneralization

occurs when an argument takes a small or limited set of evidence and incorrectly assumes it applies to a broad, sweeping conclusion

Survey Problems

When questionnaire design, data collection, or physical land measurement produces inaccurate results that fail to represent the truth (types: biased sample, biased questions, survey liars, small sample size, and other contradictory surverys)

False Starts

when an argument assumes that two comparison groups in a study or situation are completely identical in every way except for one single factor

Possibility ≠ Certainty

occurs when an argument incorrectly assumes that because something is possible (or not proven false), it must be true, or because something is not proven true, it must be false

Implication

occurs when an argument incorrectly assumes that a person or group believes the logical implications of their stated beliefs

False Dichotomy

presents an issue as having only two choices when actually more options exist

Straw Man

when someone changes or exaggerates an opponent's argument to make it easier to attack

Ad Hominem

targets a person's character, motives, or traits instead of refuting their actual claim

Circular Reasoning

occurs when an argument uses its own conclusion as a premise for support, offering no outside proof

Equivocation

when the author changes the meaning of a word throughout an argument

Appeal Fallacies

Occurs when an argument relies on an invalid appeal to authority, or invalid appeal to public opinion instead of actual evidence

Irrelevant

where an argument presents premises that do not actually support the claimed conclusion

Percentages ≠ Numbers

where someone treats a percentage change as if it represents an actual number change, or vice versa