test #4/final Flashcards
subarguments
SUBARGUMENTS: an argument within an argument that provides indirect support for the main argument/conclusion
INTERMEDIATE CONCLUSION does two things at once: is the premise in the main argument and conclusion of the subargument and
a premise part of a subargument if it offers reason/support/evidence for another premise
a premise in the main argument can be a conclusion of a subargument!!!
tips on a subargument
- identify premise and conclusion indicators
- identify argument patterns
- if a premise is offered in support of another premise, then its a subargument
- add justifications on the subarguments and make sure they make sense
- the premise of the subargument always goes above the premise/conclusion it supports
subarguments and implicit premises
we could add implicit premises to make the subargument/main argument valid
adding implicit premises is not adding subarguments, its just making explicit what the author intended to mean
- only add them when the primciple of charity allows it
- always label them in your reconstruction
- adding implicit premises is not necessarily cheap validity
- adding implicit premises where appropriate can help us better evaluate the argument
- making these implicit premises explicit makes it easier to question the reasonability of the subarguments
implicit/linking premises are usually IF - THEN premises
the point of evaluating arguments
evaluating arguments is NOT about being hyper-critical, excessivelt negative, nit-picky, or “winning”
evaluating arguments IS about figuring out:
- what is reasonable to believe (since we want to get at the truth) (i.e. believing)
- what is not reasonable to believe (since we want to avoid error) (i.e. disbelieving/suspending judgment)
and since our beliefs inform/shape our actions, evaluating argument IS also about figuring out:
- what actions are reasonable to perform
- what actions are not reasonable to perform
6 basic rules of argument evaluation
1) don’t criticize an argument by (merely) denying its conclusion
- disagreeing/having a different opinion isn’t enough to defeat the argument or deem it invalid/non-cogent
- be open-minded
- watch out for disconfirmation bias (being excessively critical of arguments whose conclusions we happen to not like, or whose conclusions we already thought were false)
- you should focus on premises and give reasons, such as the following:
- a) if the argument is ill-formed, point out that the premises just don’t support the conclusion
- b) if the argument is valid, focus on whether the premises are r/j/r to believe (even if the argument is valid, the premises may be unreasonable to believe– its not a strong argument)
- c) if the argument is cogent, focus on whether the premises are r/j/r to believe and whether the argument is defeated (its not a strong argument)
- so, your criticisms should be that it is ill-formed, the premises are not r/j/r, or the argument is defeated
2) don’t accept an argument simply because you believe the conclusion
- agreeing with/liking the conclusion doesn’t mean the argument is well-formed/ a good argument
- watch out for confirmation bias (when we’re biased in favor of arguments that support views that we already hold)
- recall that true conclusions can have weak arguments! (-ill-formed) (bad arguments are not good just because their conclusion is correct/you agree with it)
- you should focus on reasons and whether an argument provides good reasons for believing the argument
- dont do this because you might accept other arguments with the same conclusions even if theyre no good, and also other people might see you as a critical thinker whose opinion is worth considering
3) direct your criticisms at individual premises (or inferences)
- criticisms should focus on:
- a) individual premises as not r/j/r to believe because either you have good reason to believe the premise is false or suspend judgment about it
- b) individual inferences as either invalid or not cogent (even if the premises are r/j/r, they may not necessarily be enough support for the conclusion)
- dont just say there is something is wrong with the argument, direct your criticism to something specific
4) make your criticisms of premises substantial
- substantial criticisms must include reasons to think that the premise really is false, or reasons to think that suspension of judgment is the proper attitude to take toward the premise
- the simple assertion that it might be false is insubstantial
- a substantial criticism of a premise gives reasons to think the premise is not r/j/r to believe because either you have good reason to think the premise is false or to suspend judgment about it
- insubstantial criticisms may appear to be significant but actually fail to identify a real flaw in the argument; they use argument stoppers (e.g. “that premise hasn’t been proven”, “that’s your opinion”, “that’s just a subjective judgment”)
- opinions without reason is worthless
5) don’t accept the conclusion of two competing arguments
- its fundamentally irrational to believe a contradiction/that both arguments are equally strong
- its irrational because youre believing that some claim is both reasonable to believe and not reasonable to believe
- if so, suspend judgment about the merit of both arguments
- two competing arguments cant both be strong, but they can both be weak
6) don’t (merely) object to intermediate conclusions of compound arguments
- this is like rule 1, just with subarguments (compound arguments)
- in a subargument, you shouldn’t just criticize a premise (with a dual hat role) but criticize the reasons offered for that premise or the inference leading to it
- exception: it is legitimate to object to an intermediate conclusion when you think the sub-argument is inductive and defeated
guidelines for evaluating/criticizing (certain types of) premises (just list them)
1) specific factual claims
2) generalizations
3) compound sentences
- conjunctions
- disjunctions
- conditionals
guidelines for evaluating/criticizing (certain types of) premises (SPECIFIC FACTUAL CLAIMS)
1) SPECIFIC FACTUAL CLAIMS
- based on the total available evidence you have at a given time, you should either believe, disbelieve, or suspend judgment about such claims
- recall: the higher the stakes, the more evidence we require for believing a premise
guidelines for evaluating/criticizing (certain types of) premises (GENERALIZATIONS)
2) GENERALIZATIONS
All A’s are B’s”
- VERIFY: need to show the universal generalization is true (harder)
- FALSIFY: need only one counter example is enough (very easy)
- e.g. to falsify “all swans are white” you need only one example of a black swan to falsify it
“Most As are Bs”
- VERIFY: need to show that over half/at least 51% of the As are Bs
- FALSIFY: need to show that less than half/49% of As are Bs (there are less As than Bs) or that there is the same amount of As as there are Bs
“Some As are Bs”
- VERIFY: need good reason to believe at last one A is a B (very easy) (e.g. need only one example of a girl with red hair to believe some girls have red hair)
- FALSIFY: need to show that absolutely no As are Bs (harder)
to criticize, either provide a counter-example or explain why it is false
- e.g. “All animals are green” can be criticized with a counter-example
- e.g. “All people who have brothers are male” can be criticized merely by explaining that females also have brothers
guidelines for evaluating/criticizing (certain types of) premises (COMPOUND SENTENCES) (conjunctions + disjunctions)
3) COMPOUND SENTENCES
conjunctions (“A and B”)
- evaluate each each of the conjuncts separately
- for the whole conjunction to be true, both conjuncts separately have to be true/reasonable to believe
- if either conjunct is false, the whole conjunction is false
disjunctions (“A or B”) (argument by elimination)
- for the disjunction to be true, either/only one disjunct has to be true/reasonable to believe
- if both disjuncts are false, then the whole disjunction is false
- to disprove this, you have to prove that the disjunction is not reasonable to believe because there is a chance neither are true, and there are other alternatives/options (you are justified in suspending judgment about it/disbelieving it because there could be other possible options)
- the disjunction is not true when it applies to false dichotomy (its not excluive nor exhaustive)
- “Are the options in that disjunction the only options? Are there
other reasonable alternatives?” if the answer is yes, then the disjunction is not r/j/r to believe
- INCLUSIVE INTERPRETATION: “A or B or both”
- used more in logic because we want to be open to possibilities
- EXCLUSIVE INTERPRETATION: “A or B but not both”
alternatives of disjunctions (exhaustive vs non-exhaustive) (exclusive vs non-exclusive)
exhaustive and non-exhaustive discuss whether its complete/comprehensive
ask “are these all the possible options?”
EXHAUSTIVE: covers/exhausts all possibilities
- there’s no other option/choice
- e.g. a menu where you can order something not on the menu
NON-EXHAUSTIVE: does not cover/exhaust all possibilities
- there’s still another option
- e.g. a special menu that doesnt include all regular menu items
exclusive vs non-exclusive discuss whether the alternatives rule each other out
ask “do these options rule each other out?” “is it possible to only be/have one and not the other?”
EXCLUSIVE: can only have one and not both/all at once
- e.g. can order only one item on the menu
NON-EXCLUSIVE: can have both/all
- e.g. can order everything on the menu
different combinations of alternatives
EXHAUSTIVE + EXCLUSIVE: includes all options but you can’t get both/all at once
- e.g. everyone in this room is either pregnant or not pregnant
- there’s no other option (exhaustive) + you have to be either one/you cant be both at once (exclusive)
EXHAUSTIVE + NON-EXCLUSIVE: includes all possible options but you can get more than one
- e.g. a list of all the TMU degrees on the TMU website
- it is comprehensive of all the degrees you can get at TMU (exhaustive) but you can have more than one degree from TMU (non-exclusive)
NON-EXHAUSTIVE + EXCLUSIVE: doesnt include all options but you can only have one at once
- e.g. you’ll either get an A or a C at the end of this course
- its not a complete list of all the possible grades you can get (non-exhaustive) but you can’t get both at the same time (exclusive)
NON-EXHAUSTIVE + NON-EXCLUSIVE: doesn’t include all your options and you can have both/everything
- e.g. sandwich and soup for lunch
- there are other options on the menu (non-exhaustive) but you can get both (non-exclusive)
the fallacy of false dichotomy
FALLACY OF FALSE DICHOTOMY: the premise(s) claim/assume that a choice between two alternatives is exhaustive/exclusive, when the choice is not
- these premises are not r/j/r to believe
- presents less choices than actually exist
- make you feel limited
- e.g. “You’re either against us or for us” … you can also be neutral
- e.g. “You’re either a teacher, or a student” … there are other options and you can be both at the same time
guidelines for evaluating/criticizing (certain types of) premises (COMPOUND SENTENCES cont.) (conditionals)
CONDITIONALS (“if A then B”)
- dont claim that the antecedent and the consequent is true, but that there’s a relationship between the two (either a valid, cogent, or ill-formed one)
- e.g. “if you study, then you will pass” does not claim that you will study or you will pass, but that theres a special relationship between studying and passing, and if you were to study, it is probable that you will pass
there are 3 cases to consider:
a) if the antecedent is true, the consequent is guaranteed to be true
- valid form of affirming the antecedent
- you should re-phrase it to make the proposed connection obvious
- e.g. if susan is a sister, then she (definetley) has a sibling
b) if the antecedent is true, the consequent is probably true
- cogent
- you should re-phrase it to make the proposed connection obvious
- if adam is a basketball player, then he is (probably) over six feet tall
c) if the antecedent is true, the consequent is neither guaranteed to be true nor probably true
- ill-formed
- you should reject it
- e.g. if today is thursday, then monkeys like bananas
PERFORM A TEST (like the validity test)
- imagine… if the antecedent were true, what does that mean for the consequent?
if the antecedent were true…
- and the consequent has to be true, you should BELIEVE the conditional
- and the consequent is not guaranteed to be true, you should DISBELIEVE the conditional
- and you can’t tell whether the consequent is guaranteed to be true, you should SUSPEND JUDGMENT
in short, when it comes to conditional premises, 1) perform the test/ask questions, 2) rephrase it/reject it, and 3) believe, disbelieve, or suspend judgment
necessary and sufficient conditions
sometimes we reason about what to believe/do by thinking about what is necessary or sufficient
NECESSARY: is required/the only way
- e.g. “the restaurant claims to provide excellent service, but if it did, then their waiters would pay attention to detail” (this person is saying that the conseqeunt is necessary for the antecedent)
SUFFICIENT: guaranteed but not necessarily required
- e.g. “Whenever there is fire, there is sure to be oxygen (doesnt say that fire is necessary to have oxygen, but that fire guarantees oxygen/if you have fire, then you have oxygen)
necessary conditions
NECESSARY CONDITIONS: something is essential for something else
- when a is absent, b cannot be occur
- when a is false, b must also be false
- SO: a is necessary for b
-a: oxygen
b: fire
“if oxygen is present, then fire occurs”
- oxygen is necessary for fire
- a: unmarried
b: bachelor
“if Jim is unmarried, then Jim is a bachelor” - being unmarried is necessary to be a bachelor
ask yourself:
could you have b without a occurring?
could b be true while a is false?
- if the answer is no, then you have a necessary condition
sufficient condition
SUFFICIENT CONDITION: something guarantees something else, but is not required by it
- when a is the case, b must be the case
- when a is true, b must also be true
- SO: a is sufficient for b, but not necessary
- a: you get an A in the class
b: you pass the class
“if you get an A in the class, then you pass the class” - getting an A is sufficient for passing, but not necessary/the only way to pass (you could pass by getting anything above 50%)
- a: fifi is a poodle
b: fifi is a dog
“if fifi is a poodle, then fifi is a dog” - being a poodle is sufficient for being a dog, but not necessary/the only way to be a dog (fifi can be a dog by being a different breed)
ask yourself:
could you have a without b occurring?
could a be true while b is false?
- if the answer is no, then you have a sufficient condition
a key connection:
- a is sufficient for b = b is necessary for a
- “if you have fire, then you have oxygen” (having fire is sufficient for oxygen, and having oxygen is necessary for fire)
- e.g. “if fifi is a poodle, then fifi is a dog” (being a poodle is a sufficient condition for being a dog, and being a dog is a necessary condition for being a poodle)
- e.g. “if i get an A, then i will pass” (getting an A is sufficient for passing, and passing the course is necessary for getting an A)
relation between necessary and sufficient conditions
1) a can be necessary but not sufficient for b
2) a can be sufficient but not necessary for b
3) a can be both necessary and sufficient for b
but, not all conditions are either necessary or sufficient for each other
-e.g: a: being a tmu student ; b: being a sociology student
- a is not necessary for b cause you can be a soc student elsewhere
- a is not sufficient for b because you can be a different tmu major
- b is not sufficient for a cause you can be a soc student elsewhere
- b is not necessary for a cause you can have a different major at tmu
conditional sentences express necessary/sufficient conditions
conditionals state that one claim is necessary for another
- the conseqeunt is necessary for the antecedent to be true
- the antecedent is sufficient for the conseqeunt to be true
we can use a conditional sentence to state that one condition is SUFFICIENT for another
- the truth of the ANTECEDENT would be ENOUGH for the CONSEQUENT to guarantee be true too
- e.g. “if you get a D, then you will pass” (if this is true, it is guaranteed that you will pass if you get a D, and passing is necessary for getting a D)
we can use a conditional sentence to state that one condition is NECESSARY for another
- the truth of the CONSEQUENT is NECESSARY for the truth of the ANTECEDENT
- e.g. “if you make an apple pie, then you must have apples” (if this is true, then having apples is a necessary condition for making an apple pie, and making apple pie is sufficient/guarantees you have apples)
“If A, then B” claims that:
- the truth of the antecedent suffices for the consequent to be true
- the truth of the consequent is necessary for the truth of the antecedent
- e.g. “If there is fire, then there is oxygen”
- e.g. “If you make chicken noodle soup, then you must have noodles”
main summary for necessary and sufficient conditionals
so, if somebody claims “If A then B”, they’re not claiming that it is true, but that:
1) the antecedent is sufficient for the consequent
2) the consequent is necessary for the antecedent
- a conditional always contains a necessary condition and a sufficient condition
- the antecedent is sufficient for the consequent
- the consequent necessary for the antecedent
- which part is the sufficient and necessary condition can change based on the order of the sentence
“if oxygen is present, then fire occurs” - oxygen is necessary for fire
VS
“if fire occurs, then oxygen is present” - fire is sufficient for oxygen
different ways to state conditionals
- “If A then B” -> “If not B then not A”
- this is valid (contraposition) because its saying that the necessary condition is not there, and without it, the other condition cannot exist - “A only if B” -> “If A then B”
- “only if” introduces the consequent/the necessary condition (the only way to get to A is to have B, it is necessary to have B for A)
- e.g. “You can make apple pie only if you have apples” (having apples is necessary for making apple pie) is the same as saying “If you have apple pie, then you have apples” - unclear conditionals
- e.g. “to pass the course you have to study”
- 1. identify the two conditions (passing the course + studying)
- 2. try formulating the conditional in different ways (are they claiming that studying guarantees passing? probably not) (are they claiming that studying is necessary for passing? probably!)
- switch it to: “you will pass the course only if you study”
two broad types of definitions
1) REPORTIVE/DESCRIPTIVE DEFINITIONS: report/describe how language users ACTUALLY use words
2) NORMATIVE DEFINITIONS: report/describe how language users SHOULD use words
- e.g. “use the word marriage ONLY for describing a relationship between a man and a woman”
- e.g. in critical thinking class, we should use the word valid differently than we do in the outside world
- when we’re evaluating definitions, we should be clear about whether the debate is about how people actually use words or how they ought to use words
- how precise we need to be about definitions depends on the context: the higher the stakes, the more precision is needed
- sloppiness about definitions can lead to bad arguments, misunderstandings, confusion, etc.
evaluating definitions (ways definitions can go wrong: too narrow vs too broad)
a definition is TOO NARROW if it excludes things that it should not
- e.g. traditional definition of marriage excludes other couple relations
- e.g. “a student is someone enrolled at a university” is too narrow because it excludes high school students, elementary students, etc.
(being enrolled at a university is not a necessary condition for being a student but a sufficient condition; being in university guarantees that you’re a student but is not required to be a student)
- narrow = excludes
a definition is TOO BROAD if it includes things that it should not
- e.g. “a computer is an electronic device with a screen” is too broad a definition because it includes devices such as phones, tablets, etc.
(neither being an electronic device nor having a screen are sufficient conditions; they dont guarantee being a computer)
- broad = includes
counter-example
COUNTER-EXAMPLE: an example, either real or fictional, that shows that a definition is too broad or too narrow
e.g. “Dog is a four-legged mammal with a heart”
- too broad because it includes cats
- too narrow cause it excludes three-legged dogs
e.g. “Triangle is a three-sided figure containing a 90 degree angle”
- too narrow because it excludes triangles without 90 degree angles
e.g. “Car is a four-wheeled, gasoline-powered vehicle with doors”
- too narrow because it excludes battery-powered cars without doors
- too broad because it includes trucks
e.g. “Pen is an impliment for writing that uses black ink”
- too narrow because it excludes multi-coloured pens
- too broad because it includes other writing tools
ambiguity and vagueness
AMBIGUITY: a word/phrase that has more than one meaning
- e.g. “bank” can mean a financial bank or a river bank
VAGUENESS: a word/phrase that has no precise cut-off point between when it applies and when it doesn’t
- lacks clear meaning/definition
- e.g. “bald” “rich” “tall” “sleepy” (HOW bald, HOW rich, HOW tall?)
- vageuness and ambiguity dont necessarily make an argument bad, but they can cause problems…. i.e. fallacy of equivocation
