Logic: Exam 1

belief bias

believing an argument because it aligns with your views, not because it's logically sound

Thinking a poorly supported claim about the benefits of organic food is true just because you prefer organic products.

belief bias example

availability heuristic

overestimating the likelihood of events that are easy to remember

Fearing plane crashes more after hearing recent news stories about them, despite their rarity.

availability heuristic example

conjunction fallacy

assuming specific conditions are more probable than a general one

Believing it's more likely for someone to be a vegetarian and an environmental activist than just a vegetarian.

conjunction fallacy example

halo/horns effect

letting one good or bad trait influence your opinion of someone

Thinking someone is competent in all areas because they're good-looking.

halo/horns effect example

affect heuristic

making decisions based on emotions rather than evidence

Investing in a company because you like its products, not because its financials are strong.

affect heuristic example

confirmation bias

focusing on information that confirms your beliefs and ignoring the rest

Only reading news that aligns with your political views.

confirmation bias example

confirmation biases

self-verification, imposter syndrome, self-handicapping

self-verification

seeking information that confirms your self-concept

A person who sees themselves as a good leader only notices feedback that praises their leadership.

self-verification example

imposter syndrome

doubting your abilities and feeling like a fraud

Believing you need to be qualified for your job despite evidence of your competence.

imposter syndrome example

self-handicapping

creating obstacles to excuse potential failure

Procrastinating on a project to blame the lack of time for poor performance.

self-handicapping example

argument

 reasoning process where premises are given to support a conclusion, a way to justify beliefs or opinions using evidence or logic

fallacy

mistake in reasoning or argument that leads to incorrect conclusions

argumentum ad hominem

when someone attacks the person making an argument rather than the argument itself

Dismissing someone's views on health because they smoke.

argumentum ad hominem example

ad misericordiam

appealing to pity or guilt to win an argument, instead of presenting logical reasons

Arguing for a deadline extension because of personal stress, not because of issues related to the assignment.

ad misericordiam example

straw man

misrepresents someone's argument to make it easier to attack

Saying someone who promotes energy conservation hates modern technology.

straw man example

ignoratio elenchi

providing an argument that may be valid but does not address the issue in question

Arguing for better schools in a healthcare debate.

ignoratio elenchi example

ad verecundiam

citing an authority as evidence in an argument when the authority is not an expert on the facts relevant to the argument

Using a celebrity's opinion as proof of a scientific fact.

ad verecundiam example

plurium interrogationum (many questions fallacy)

combining multiple issues into a single argument as if they are one, forcing a simplistic answer to a complex issue

Asking someone if they've stopped being irresponsible, presupposing they were irresponsible before.

plurium interrogationum example

shifting the burden of proof

demanding the opponent prove their point instead of the speaker proving their own

Claiming an invention works and asking others to prove it doesn't.

shifting the burden of proof example

petito principii (begin the question/circular reasoning)

assuming in the premise what the argument seeks to prove

Saying democracy is the best form of government because democratic countries are superior.

petito principii example

false analogy

making a comparison between two things that are not truly comparable

Arguing that cars and bicycles should follow the same traffic laws because they're both modes of transportation.

false analogy example

hasty generalization

making a broad generalization based on limited or insufficient evidence

Assuming all high school students dislike math based on a few interviews.

hasty generalization example

opst hoc ergo propter hoc

assuming that because one event followed another, the first event caused the second

Believing a dance caused it to rain because rain followed the dance.

post hoc ergo propter hoc example

cum hoc ergo propter hoc

 assuming two events occurring together have a cause-and-effect relationship

Assuming ice cream sales cause shark attacks because both rise in summer.

cum hoc ergo propter hoc example

slippery slope

arguing that a small first step will lead to a chain of related (negative) events

Claiming that raising taxes slightly will eventually lead to extreme government control.

slippery slope example

affirmation of the consequent

assuming that because the consequent in an implication is true, the antecedent must also be true

If it rains, the ground is wet. The ground is wet, so it must have rained (ignoring other reasons the ground could be wet).

affirmation of the consequent example

ad ignorantiam

claiming something is true because it has not been proven false

Asserting that there must be life on other planets because no one can prove there isn't.

ad ignorantiam example

the gambler’s fallacy

believing that past random events affect the likelihood of future random events

Thinking a coin is due to land on heads after several tails in a row.

the gambler’s fallacy example

false dilemma

presenting two options as the only possibilities when more exist

Claiming you must either fully support a policy or completely oppose it, with no middle ground.

false dilemma example

contradiction

proposition never true

satisfiable

there is min. 1 situation where proposition true

tautology

proposition always true

counter-example

case that disproves a statement or theory

2 logically equivalent propositions

they are true under exactly the same conditions or false under exactly the same conditions

syllogism

argument with specific characteristic

meta-theorems

general facts

in syllogism: A, B

predicates

in syllogism: argument

3 predicates, one of them is a “middle term” in both premises, conclusion relates to other two