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73 Cards in this Set
- Front
- Back
Statement/Claim |
An assertion that something is or is not the case |
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Proposition |
The specific thought or idea that the statement expresses Different stamemts can express the same proposition Same statement can express different propositions |
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Premise |
A premise is a statement that is offered in support of a conclusion |
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Conclusion |
A conclusion is a statement that is held to be supported by one or more premises |
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Argument |
An argument is a set of statements, one of which (the conclusion) is taken to be supported by the remaining statements (premise) An argument is a group of statements in which some (the premises) are intended to support another (conclusion) |
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Inference |
An inference is process of reasoning from a premise or premises to a conclusion, based on those premises |
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The steps of Argument Analysis |
0. Figure out if it really is an argument 1. Reconstruct the argument 2. Evaluate the argument |
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The key ingredients in propositional knowledge |
Belief Truth Justification |
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Truth: Realism |
Two Claims: 1.There are truths in that subject area 2. What these truths are does not depend upon anyone's beliefs about them ( objective) |
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Truth:Nihilism |
Claims: There are no truths whatsoever in that subject area Ex. Moral Nihilism; the view that moral statements have no truth value ( they are neither true nor false) |
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Drawbacks of Nihilism |
Extremely implausible in many subject areas Nihilism about everything is seldom defeating ( the statement itself claims to be a fact) |
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Truth: Relativism |
Claims: There are truths in that subject area; but What the truths are depends upon what we believe them to be |
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Drawbacks of Relativism |
Counter examples Sounds tolerant but isn't It suggests we are infallible The view is self defeating |
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Philosophical Skepticism |
Statements have truth values but we don't know what most or all of them are |
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Drawbacks of Skepticism |
Requiring absolute certainty for a belief to count as knowledge seems to be asking too much Skepticism about everything is self-defeating |
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Each of these views deny something about truth or knowledge |
They deny something Nihilism - no truth, and be relation no knowledge Relativism- no objective truth Philosophical Skepticism - no justification |
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Two Realist Models of what makes a statement/proposition true |
The coherence model of truth The correspondce model of truth |
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The Correspondence Model of Truth |
A proposition is true just in case it describes things as they actually are. A true proposition corresponds to facts. A proposition is false just in case it fails to describe things as they actually are. A false proposition does not correspond to the facts. As a result ~ Every proposition has exactly one truth value ( at a given time) it is either false or true. Advantages... Simple & intuitive.... Avoids the drawbacks of the coherence model |
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Drawbacks of Correspondence Model of Truth |
Certain propositions don't seem to fit this model, even though we tend to think they are true or false "You should keep your promises" "You will have a hamburger for dinner tonight" |
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Advantages of Standard Form
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Excludes logically irrelevant material Allows us to make assumptions explicit Provides clarity and case of reference *It provides a clear reconstruction of the argument and that is essential to properly evaluate the argument* |
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Deductive Argument |
Intends to provide logically conclusive support for the conclusion |
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Deductive Validity |
In a world where the premises are all true, the conclusion is guaranteed to be true as well |
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The Validity Test |
Imagine that the premises are true. Assuming this, would the conclusion have to be true as well? If yes, valid If no, invalid |
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Five Sentential Connectives |
Conjunction Disjunction Negation Conditional Biconditional |
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Five Sentential Connectives: Conditional |
The antecedent - what follows the word "if" The consequent- what follows the word "then" |
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If vs Only if |
Only if introduces the consequent |
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Argument by Elimination |
P or Q ~Q Therefore P 1.Either the Maid or the Butler Killed her 2. Maid did not kill her 3. Butler did it |
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Argument by Conjunction |
Always Valid 1. Wearing shoe on right foot 2. Wearing shoe on left foot 3. Wearing shoe on left and right foot |
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Argument by Simplification |
1. Wearing shoe on left and right foot 2. Wearing shoe on right foot |
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Argument by Affirming the Antecedent ( Modus Ponens) |
This pattern is valid 1. If Ryerson is great, then many students apply here 2. Ryerson is a great university Therefore, 3. Many students apply there |
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Argument by Denying the Consequent (Modus Tollens) |
1. If you get A+, you pass 2. Didn't pass the class 3. Didn't get A+ |
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Argument by Denying the Antecedents |
1. If you get A then you pass 2. You didn't get an A 3. You didn't Pass Invalid argument pattern |
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Affirming the Consequent |
1. If you get A you pass 2. You pass the class 3. You got an A Invalid |
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Argument by Hypothetical Syllogism |
1. If P, then Q 2. If Q then R 3. If P then R Valid format |
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Argument by Universal Modus Ponens |
1. All students are hardworking ( All A's are B's) 2 . Omar is a student ( x is an A) Therefore, 3. Omar is hard working ( x is B) |
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Argument by Universal Modus Tollens |
1. All students are hardworking 2.Omar is not hardworking Therefore, 3. Omar is not a student. Valid Argument Pattern |
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Argument by Universal Hypothetical Syllogism |
1. All whales are mammals ( All A's are B's) 2. All mammals are animals ( All B's are C's) Therefore, 3. All whales are animals ( All A's are C's) |
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Argument by Ruling Out |
1.No children are perfectly behaved (No A's are B's ) 2. Jacob is a child (X is an A) Therefore, 3. Jacob is not perfectly behaved at all times (X is not a B) |
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The Cogency Test |
Imagine/suppose that the premises are all true. Assuming this, is the conclusion likely to be true as well? If yes the argument is cogent If no the argument is non-cogent |
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ill-formed |
Arguments that are invalid and not cogent are called ill-formed, since the premises do not guarantee that the conclusion is true or even probable |
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Contrast between Valid and Cogency |
Validity does not come in degrees Cogency comes in degrees: on argument can be more or less cogent than another ( depending on probability of conclusion given the premises) |
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Deductive Strength |
An argument is deductively strong ( for a person at a time) if and only if it is A. Valid, and B. Rational/justified/reasonable for the person to believe that all of the arguments premises are true, based on the available evidence |
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Weak Deductive Argument |
A. Invalid B. Not rational for the person to believe one or more of the arguments premises based on the available evidence C. Both A and B |
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Principal of Proportional Belief |
The stronger the available evidence for the premises, the more rational it is to believe them |
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Inductive Strength |
A. Cogent B. Reasonable for the person to believe that all the premises are true based on the available evidence C. The argument is not defeated by the person's total evidence
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Weak Inductive Argument |
A. Not cogent B. Not rational for the person to believe that all the premises are true based on the available evidence C. Argument is defeated by another piece of evidence D. Any combination of above |
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Justification |
Rational belief/ justified belief A. Over evidence gives overall reason to think something is true you should believe it B. Overall evidence goes against the proposition the person should disbelieve it C. If eveidence doesn't support the idea being true or false than the rational thing to do is be neutral |
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A Disjunction Statement |
Either P or Q |
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A Conditional Statement |
If P, then Q If it rains the picnic will be cancelled |
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How do you recognize arguments? |
Is the author trying to get me to believe something by giving me reasons in support of it? If yes, it is probably an argument Some contrasts: 1. Descriptive writing 2. Rhetorical writing, asserts conclusion without offering reasons |
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Cheap Validity |
You will make an argument valid, but the premise you add will not be reasonable. So, the argument will still not be a good one. It will be weak, even if it's well formed. |
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Rules governing the addition of Implicit Premises |
Add implicit premises that are consistent with the intention s of the author of the argument Add implicit premises that are reAsonable to accept rather than ones that are obviously false When adding a generalization as an implicit premises in an argument ....add a true wide generalization rather than a true narrow one, and add a true narrow generalization rather than a false wise one |
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Basic Rules of Argument Evaluation: Denying its conclusion |
1. Don't criticize an argument by (merely) denying its conclusion A. If the argument is ill-formed B. If the argument is valid C. If the argument is cogent |
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Basic Rules of Argument Evaluation: Don't accept because you believe the conclusion |
2. Don't accept because you believe the conclusion A. Watch out for confirmation bias B. A conclusion can v reasonable to believe based on just one good argument
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Basic Rules of Argument Evaluation: Criticize Individual Premises |
A. Individual Premises Good reasons to think premise is false or suspend judgement B. Individual inferences As either invalid or not cogent |
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Basic Rules of Argument Evaluation: Make your criticisms of premises substantial |
Substantial A. Good reason to think premise is false or suspend judgement Insubstantial A. " Maybe the premise is false" B. Using argument stoppers - Take argument seriously |
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Basic Rules of Argument Evaluation: Don't accept the conclusions of two competing arguments |
Can't reasonably believe a contradiction Can't rationally think both arguments are equally strong |
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Basic Rules of Argument Evaluation: Don't merely object to intermediate conclusions of compound arguments |
Critize premise leading to conclusion of sub-argument
* legitimate to object to an intermediate conclusion when you think the sub-argument is inductive and is defeated* |
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Fallacy of False Dichotomy |
When the premises claim or assume that a choice between two alterni is exhaustive or exclusive or both when the choice is not Not reasonable to believe |
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Intermediate Conclusions |
Intermediate Conclusions of Compound Arguments |
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Fallacy of Equivocation |
When an ambiguous word or expression is used in two different senses in an argument....But the argument appears to suggest otherwise |
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Slipper Slope Fallacy |
A particular step will lead to further undesirable step or steps. Sometimes even if a phrase is reasonable to believe it can still be illegitimate to use in an argument |
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The fallacy of Hasty Generalizations |
" All the cafeteria foods is terrible. I had a burger there once, and it made me queasy." |
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The Fallacy of Begging the Question |
Attempting to prove a conclusion by using the same conclusion as premise. |
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The fallacy of composition |
Arguing or assuming that what is true of the parts is true of the whole |
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The Fallacy of Division |
Arguing or assuming that what is true of the whole is equally true of the part |
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Appeal to popularity |
Arguing that a claim must be true if it is a popular belief |
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Appeal to common practice |
Arguing that something should be done a certain way if it is commonly done that way |
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Appeal to tradition |
Arguing that a claim must be true if it is part of a tradition |
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Appeal to Ignorance |
We don't know that P is true/false God must exist since science hasn't shown otherwise |
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Ad Hominem Fallacy |
Rejecting a claim by criticizing the character or circumstance of person making the claim Tu Quoque Points out hypocrisy |
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Two ways that a belief can be unjustified |
Motivational errors - Confirmation Bias Failing to weigh evidence properly ( four versions of this) - ignoring some evidence - undervaluing contrary evidence - overvaluing confirming evidence - overvaluing psychologically available evidence......weight to memorable..vivid or striking evidence ......weight to memorable..vivid or striking evidence |
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Argument Stoppers |
Who's to say the truth is about that That's a subjective judgement I would prefer not to think about it * not thinking about argument |