Understanding Arguments and Logical Fallacies

Statement

A sentence that can be true or false.

Argument

A series of statements supporting a conclusion.

Premise

A statement supporting an argument's conclusion.

Conclusion

The final statement derived from premises.

Conclusion indicators

Words indicating a conclusion: so, therefore, hence.

Premise indicators

Words indicating premises: because, since, firstly.

Intermediate conclusion

A conclusion serving as a premise for another. -

P1 - i am allergic to most nuts

IC - i am probably allergic to walnuts

C - i shouldnt eat this cake with walnuts in it

Deductive argument

An argument where conclusion necessarily follows premises.

hillary clinton must be intelligent because shes a lawyer and lawyers are intelligent

Inductive argument

An argument where conclusion extends beyond premises.

everytime i have eaten oysters i have been sick, so oysters must always cause sickness

Cogent inductive argument

A strong inductive argument with true premises.

Conductive argument

An argument with convergent premises supporting a conclusion.

P1 - they are friendly

P2 - they keep you active

C - you should buy a dog

Valid argument

An argument where true premises guarantee a true conclusion.

all politicians are liars. john is a politician. therefore, John is a liar

Sound argument

A valid argument with all true premises.

most cats have tails. most cats have ears. there is at least one cat with a tail and ears

Standard form of an argument

Structure: P1 - P2 - C.

Linked argument structure

Premises connected to a single conclusion.

edinburgh is in scotland. scotland is in the uk. edinburgh is in the uk

Serial argument structure

Sequential premises leading to a conclusion. involves an intermediate conclusion

Convergent argument structure

Multiple premises supporting a single conclusion. also known as conductive

Analogical explanation

Compares concepts to aid understanding.

life is like a box of chocolates

Analogical argument

Argues similarity between two objects based on properties.

callum and harris both have brown hair

harris is pretty

therefore, callum is pretty

Counter examples

Examples disproving a universal statement.

"all swans are white" - this swan is black

Informal fallacy

an argument which may be formally valid yet is fallacious because it has false premises

Ad hominem abusive

Attacks opponent with irrelevant insults.

i aint listening to harris because he is clapped

Ad hominem circumstantial

Accuses opponent of self-interest in argument.

im not buying harris's shoes off of him because he only wants my money

Ad hominem tu quoque

Attacks opponent's past actions instead of argument. im not buying thse shoes harris told me to because he said they were ugly a couple days ago

Confirmation bias

Favoring information that confirms existing beliefs.

Fallacious appeals to emotion

Using emotion instead of reason to persuade.

my dad told me to finish my dinner because there are starving africans out there

Legitimate appeals to emotion

Emotionally valid reasons for argument.

you should bring me to the hospital because i just broke my leg and it hurts

Post hoc ergo propter hoc

Assuming causation from sequential events.

i failed my exams because i didnt take vitimans on the days i had them

Lexical ambiguity

A word with multiple meanings.

you should call me a taxi

Syntactic ambiguity

A sentence with multiple grammatical interpretations.

the child ate the cookies on the couch - the child OR the cookies could have been on the couch

illegitimate appeals to authority

Claim accepted based on authority without justification.

my friend told me no one checks if you have your phone with you in the exam so i think itll be okay

Legitimate authority

Expertise and reliability in a specific field. miss davidson told me that kant was a deontologist

Slippery slope argument

Claiming one action leads to a series of undesirable outcomes.

if we legalise cannabis then everyone will buy it

then everyone will be high all the time

then babies will start smoking weed

Acceptable slippery slope argument

Logical progression of consequences in an argument.

we shouldnt vote for brexit. if brexit happens, our imports will cost more money. if that happens, everything will cost more. if that happens, inflation will skyrocket.

Inappropriate analogies

Differences undermine the reasoning in analogies.

truth

relevance

number of points

Denying the antecedent

formal fallacy

Form: If P then Q; Not P; therefore not Q.

if it is monday then we have philosophy period 6

it aint monday

we dont have philosophy period 6

Affirming the consequent

Form: If P then Q; P; therefore Q.

if it is monday we have philosophy period 6. we have philosophy period 6, therefore it is monday