Logic Flashcards
logic is the study of rational argumentation. it’s objective.
Belief is not same as logic. Reasons for beliefs: - self interest - consistency - coercion - aesthetics
argument has conclusion and premises. every argument has only one conclusion, only one! no conclusion, no argument. but argument can have any number of premises.
It’s crucial to correctly identify the conclusion and not misunderstand conclusion with premises and vice versa, otherwise it will lead to misargument.
Conclusion indicators:
therefore, so, hence, ergo, thus.
But these words not always lead to conclusions. i.e. “so” can means “very”
Premise indicators-
Because, Since, Given that.
again, not every use of these words point out a premise. i.e. Since I’m hungry, I want to eat …. This is not a premise.
Sometimes there are no indicators words before premises. as long as we can naturally insert “because…” “ therefore”
sometimes we skip some obvious premise (called suppressed or implicit premise) in an argument, which is called Enthymeme.
two types of arguments: deductive and inductive.
deductive is that conclusion is no broader than premises - non ampliative - the conclusion is contained within the content of premises. it moves from broad to narrow. the conclusion is absolutely certain.
induction is from narrow to broad, so conclusion is only probable and not certain.
An argument should be validated by two dimensions : validity and well-grounded
Validity: it’s about the structure-whether conclusion follows premises. it doesn’t judge whether premises are actually true or not.
well-grounded: based on only true premises
when an argument is both valid and well-grounded, it’s a sound argument.
formal logic concerns about on validity/form of an argument while informal logic looks at acceptability of an argument.
what are the typical fallacies of informal logics?
- circular argument i.e. A is because A
- (semantic) equivocation: it occurs when a key term or phrase in an argument is used in an ambiguous way, with one meaning in one portion of the argument and then another meaning in another portion of the argument.
- distinction without difference - The assertion that a position is different from another position based on the language when, in fact, both positions are the same – at least in practice or practical terms. i.e.
- use leading question (a connotative language) to beg the agreement - there is no grounded evidence to support it
an example of distinction without difference
Sergio: There is no way I would ever even consider taking dancing lessons.
Kitty: How about I ask my friend from work to teach you?
Sergio: If you know someone who is willing to teach me how to dance, then I am willing to learn, sure.
an example of equivocation
Examples: I have the right to watch “The Real World.” Therefore it’s right for me to watch the show.
what is fallacy of appealing to authority?
when appealing to authority, there are 3 requirements
- authority has to exist, not based on hearsay “I heard from somewhere that …”
- authority has to be an expert
- the authority to be object, impartial.
what is fallacy of appealing to common opinion?
something is true is because it’s widely believed.
what is fallacy of novelty?
“new is better is just because it’s new” is a fallacy.
what is fallacy of appealing to tradition?
something is true is because it exists for a long time.
what is fallacy of analogy/disanalogy?
faulty analogy is that drawing an inference from an analogy which has no similar structure of another thing.