reasoning Flashcards
reasoning
involves using knowledge within systems of formal logic
you have some knowledge of the world and how things are causally linked that allow you to come to some conclusion
2 types of reasoning
* inductive reasoning
* deductive reasoning
inductive reasoning
specific facts = draw general conclusions
going from specific facts and drawing general conclusions from them
* primary ways to make predictions and generate knowledge about the world
Plato, Aristolte, Wundt, Skinner were all mortal….therefore all humans must be mortal
deductive reasoning
general claims - asks what follows from these premises (go to more specific claims from there)
All humans are mortal. James is a human. Therefore James is normal
more research
which type of reasoning can you be more certain of
* has to do with how you think about things
syllogisms
basic reasoning puzzle – given premises, does the conclusion follow?
– uses deductive reasoning
example:
* all men are mortal
* socrates is a man
* therefore, socrates is mortal
syllogisms that don’t follow logically
If spot is a lizard
spot is not a lizard
therefore, spot is not an animal
if you clean your room, I will give you $10
you do not clean up your room
therefore, I do not give you $10
syllogisms that follow logically
no democrats are conservatives
some Americans are conservatives
therefore some Americans are not democrats
no healthy things are cheap
some vitamin pills are cheap
therefore, some vitamin pills are not healthy things
why are syllogisms hard
belief bias: the tendency to think that a syllogism is valid if its conclusions are believable
true and valid are not equivalent
true: the way the world as we know it works
valid: logically follows from premises
we are bias to see what we believe to be true to be logically valid as well
syllogisms do not reflect how people view the world
most of the time we use knowledge about the world and if the conclusion is believable, we say its logical even if it doesn’t formally make sense
we tend to confuse something that follows logically vs something that is valid
what makes it difficult?
* quantifiers
* negation
quantifiers make syllogisms hard
the word “some”
none of the athletes is a student
some of the clerks are students
therefore
valid inference: some of the clerks are not athletes
negation makes syllogisms harder
a refusal or denial of something
if it is friday night, then Bill is drunk.
It is Friday night
therefore Bill is Drunk
if it is Friday night, then Bill is drunk
Bill is not drunk
Therefore it is not Friday night
(doesn’t say anything about if he is not drunk)
syllogisms summary
- better at reasoning if we do not use quantifiers and negation
- better when consistent with beliefs
propositional reasoning
an assertion (or proposition) that is tested
Today is Monday
– is it Thursday?
– respond if true (yes or no)
have a statement and you answer if it’s true or not
wason card selection task
making syllogisms more complicated
rule: if a card has an “A” on one side then it has a “4” on the other side
A B 4 7
– to test this, cards A and 7 must be turned over
A only 33% turned over
A and 4 45% turned over
A and 7 4% turned over
propositional reasoning – Modus Ponens
Latin - mode that affirms
If P, then Q
P.
Therefore Q
testing A
propositional reasoning – Modus Tollens
latin: the way in which this is denied (finding a case in which this rule is broken)
- you need to find an example where Q is false
If P, then Q.
Q is false (or not Q)
Therefore P is false (or not P)
testing the 7 because if there is an A behind, you have an example card that disproves the rule
people get more hung up on this part
why is the Wason Card selection task so difficult?
falsification principle: to test a rule, you must look for situations that falsify the rule
tendency to try to affirm the rule each time
training in logic doesn’t help: researchers found little improvements for college students who had just taken a logic course
experience with situations help
wason card selection vs experience
if a person is drinking beer, then that person is over 19
found that if you put the same problem in an experience than you do fine
* using real world knowledge
to test this rule – should pick the drinking beer option and the NOT over 19 option to see if the rule applies
seeing if the not over 19 are drinking beer to negate the rule
confirmation bias
the tendency to only look for information that supports your existing beliefs
Wason 246 task
* find a rule that generates correct 3 number sequence
* 2-4-6 is a correct sequence
* search for the rule by testing as many sequences as you want
the rule is that the sequence has to increase
* people guess with similar patterns
* you figure it out by suggesting numbers going down
rarer for people to come up with sequences that breaks the rule, which makes it harder to determine the rule
the 2-4-6 task
Twenty
* tested a variation of the 246 task
* participants were instructed to find two rules rather than just one
rules:
* DAX: 3 accendng numbers (Wason’s original rule)
* MED: any other triple (does not obey the DAX rule)
each time a triplet of numbers was suggested by participants, they were told if it was either a DAX or a MED triplet
people were much better at discoverng the DAX rule than in Wason’s original study
– shows how the way a task is presented affects how it is tackled
DAX is providing sequences that breaks rule, people are less likely to fall into the confirmation bias
** harder for people to come up with example that disprove rather than proving a problem
scientific reasoning and confirmation bias
confirmation bias can influence science
hypothesis testing:
* generate an explanation for some phenomenon
* design experiment to test it
confirmation bias:
* if results confirm hypothesis more likely to believe it is true
how do we fight against this tendency?
* falsification principle: look for situations that falsify the hypothesis
scientists are more likely to come up with stuff to confirm a hypothesis rather than one that negates it
reasoning – implications
reasoning is not just abstract logic
experience affects reasoning
assumptions we make are critical
* our believes and experiences at how the world works
* in effect they add premises
general knowledge of the world will affect how you judge a conclusion
