Principles of Reasoning Exam 1 Flashcards
proposition
anything that is capable of being true or false (has true values)
is water=h2o a proposition?
yes
is dad! do the perfect case! a proposition?
no, it is an imperative statement (command or request)
is water=sodium chloride a proposition?
yes, it is a statement that can be either true or false
do the sentences below express the same proposition?
1. the snow will melt before the end of next week
2. the end of the week will come after the snow melts
-no, the first sentence implies the snow melting in relation to the end of the week; the second sentence implies the end of week in relation to the snow melting
connectives
link propositions to other propositions
examples of connectives
and, if, or, not, then, because, before, after,while, when, either
is this an example of a connective component:
the Milky Way is 100,000 light years across the universe, and that’s news to me
no, even though the word “and” is being used, the second part of the sentence is not a proposition, but an imperative sentence
is this a connective component:
if the sun disappeared right now, then the sky would go dark in 8 minutes
yes, the first part of the sentence is a hypothetical proposition which could be proven true or false, and the second statement is a proposition that can be proven true or false as well
is this a connective component:
the statement on this slide is not true
no, although it uses not, this is an example of the liar paradox, and it is not a proposition statement combined with another
other examples of propositions
- baltimore is to the north of canada
- batman wold beat superman in a fight
- if my phone is working, then it is charged
argument
when at least one premise is put forward in a favor of a conclusion
conclusion indicators
therefore, thus, hence, consequently
premise indicators
since, because, given that, granted
deductive argument
aim to show that a conclusion is guaranteed if all the premises are true
valid argument
guarantees a true conclusion if the premises are all true
sound argument
valid+all true premises=sound
inductive argument
aim to show that the conclusion is probable given its premises
strong argument
-has a probable conclusion given all true premises
what is the premise:
since my phone is working, it must be charged
my phone is working
what is the conclusion:
batman would beat superman in a fight, and superman would easily beat joker in a fight. so batman would easily beat joker in a fight
batman would easily beat joker in a fight
independent premise
separate lines of evidence in favor of a conclusion
dependent premise
premises that work together to support the conclusion
subconclusion
a premise that supports a conclusion, and that conclusion itself is a premise for another conclusion
fallacies
bad arguments
subjectivist
I believe it, so it’s true
appeal to majority
everybody believes it, so it’s true
ad hominem
something’s wrong with you, so you’re wrong
appeal to authority
they’re an expert, so they’re right
(could be the wrong kind of authority or the authority might not represent the consensus position)
false alternative
failing to account for other possibilities
post hoc
A happened before B, so A caused B
hasty generalization
it happened once, so it happens all the time
accident
it’s generally the case, so it’s definitely the case in this instance
composition
the parts have a characteristic, so the whole thing has that characteristic
(part to whole)
division
the whole thing has a characteristic, so the parts have that characteristic
(whole to part)
begging the question
assuming the conclusion is true in the premises
equivocation
changing the meaning of a term mid-argument
appeal to ignorance
you can prove it isn’t true, so it is true
diversion (red herring)
changing the subject
straw man
misrepresenting an opponent’s argument to make it easier to attack
cognitive bias
psychological tendencies that lead to reasoning errors (not the same as fallacies)
confirmation bias
tendency to more easily find evidence that supports our preconceptions, but not evidence against it
halo effect
when you like someone, it is easier to notice their good qualities than their bad ones
belief bias
mistaking an argument with a conclusion you like for a good
argument/mistaking an argument with a conclusion you don’t like for a bad argument
belief bias example
I agree with the conclusion, that means it’s a good argument
hindsight bias
judging events as predictable after they have already happened
hindsight bias example
-i knew that was going to happen
-i should have known
representative heuristic
judging events that something belongs to a group based on a stereotype
representative heuristic example
thinking someone is a librarian because they look like one
availability heuristic
judging how frequently events happen by how quickly examples come to mind
availability heuristic example
ever since jaws came out, shark attacks have been up
anchoring
judging a quantity based on a reference point
anchoring example
those shoes were $350 before they went on sale, now they’re $250, that’s $100 cheaper
cognitive dissonance
the uncomfortable feeling that results are from behaving out of step with your self-concept
cognitive dissonance example
a frugal person might feel a negative emotion if they go on a shopping spree
attribution bias
attributing your own behaviors to external factors and other people’s behavior to internal factors
attribution bias example
I lied because I was in a tough situation, but you lied because you’re a bad person
invalid argument
when it is possible for all the premises to be true and the conclusion to be false
unsound argument
when it is either invalid or does not have all true premises
what must a deductive argument be?
sound
can a sound argument have some false premises?
no, because a sound argument must be valid and have all true premises
can a valid argument have all true premises and a false conclusion?
no, because a valid argument guarantees a true conclusion
can a sound argument have a false conclusion?
no, because a sound argument must be valid and have all true premises, and a valid argument guarantees a true conclusion
can a cogent argument have all true premises and a false conclusion?
yes, because a cogent argument makes the conclusion probable, not certain, therefore it could be false
can a valid argument have all false premises?
yes, because as long as the conclusion follows the premises, those premises could be true or false
can an invalid argument have a true conclusion?
yes, because invalidity refers to the conclusion not following the premises, but the conclusion could happen to end up being true
can an unsound argument have a true conclusion?
yes, because there could be one true premise, one false premise, but the conclusion just happens to be true
cogent argument
strong+all true premises
which are the fallacies of relevance?
subjectivist, appeal to majority, appeal to emotion, appeal to force, straw man, red herring
which are the inductive fallacies?
appeal to ignorance, hasty generalization, post hoc
which are the fallacies of presumption?
false alternatives
which are the fallacies of ambiguity?
composition, equivocation
fallacies of ambiguity
fallacies that involve unclear language or unclear concepts
fallacies of presumption
fallacies that involve unwarranted assumptions
inductive fallacies
fallacies that involve insufficient evidence
fallacies of relevance
fallacies where the premises are irrelevant to the conclusion
appeal to emotion
attempting to win an argument by manipulating emotions such as fear or pity
appeal to force
in which someone tries to convince others to accept a conclusion by using threats, intimidation, etc.
