Invitation to Critical Thinking Chapter 10 Lecture Notes Chapter 10 Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Overview Evaluating Premises: Self-evidence, Consistency, and Indirect Proof Tautologies Truisms by Definition Contingent Claims Values Relativism Self-evident Claims Beyond Self-evident Claims Consistency Implications Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Evaluating Premises All arguments have to start somewhere Every argument will have unsupported premises When designing and constructing an argument, establish as firm a foundation as possible Experienced arguers use the most “basic” premises as claims uncontroversial as easy to accept as hard to challenge or refute Two “basic” premises or claims are tautologies and truisms by definition Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Tautologies A claim that you can't deny without formally contradicting yourself considered to be necessarily true though tautologies always carry the value “true,” they don't convey much information Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Example of Tautology Either the President knew in advance of the arms-for-hostages deal or he didn't. If he did know of the arms-for-hostages deal in advance, then he's involved in the cover-up and therefore unworthy of his office. If he didn't know of the arms-for-hostages deal in advance, then he's not in control of his own administration, and is therefore unworthy of his office. Therefore, either way, he’s definitely unworthy of his office. Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Truisms by Definition The terms of the claim reveal the truth of the statement Anyone who understands the meanings of the terms in the claim will immediately recognize any such statement as true Invitation to Critical Thinking Chapter 10

Examples of Truism by Definition Murder is a form of homicide All bachelors are unmarried Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Contingent Claims Claims that are neither self-contradictory nor necessarily true are called contingent Contingent claims’ truth or falsity depends on something outside of themselves Something beyond their formal structures Something beyond the meanings of their terms Invitation to Critical Thinking Chapter 10

When Evaluating Contingent Claims, ask What kind of claim is being made here? Does the premise make a factual claim or an evaluative claim? Does it offer an interpretation? What sort of issue does it raise? What sorts of additional support might this claim need? Invitation to Critical Thinking Chapter 10

Examples of Contingent Claims All men are created equal Not all men are created equal Some men are created unequal Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Values Relativism More reasonable and understandable than Relativism in general because evaluative issues (which cannot be resolved by doing science or looking things up generally) are harder to resolve than factual issues Some hold that values relativism can't be done due to the essential difference and an unbridgeable gap between facts and values It doesn't follow from the fact that evaluative claims can't be established empirically that they can't be established at all To resolve evaluative claims, consider and evaluate the best available arguments on all sides of the issue Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Self-evident Claims Self-evident claims: the supporting claims are no more basic or evident than what they support To support them by appeal to further observations would be no more basic or evident than what they support Unless there is good reason for doubting them, such claims may be taken as self-evident Invitation to Critical Thinking Chapter 10

Examples of Self-evident Claims Human life is precious Peace is precious Freedom is better than colonial bondage as a way of life Basic human rights belong equally to each and every human being Invitation to Critical Thinking Chapter 10

Beyond Self-evident Claims To determine if a claim is beyond a self-evident claim, ask Is it an interpretation? This means other interpretations are possible This means this is an interpretive issue An interpretation is the kind of claim one can always legitimately be challenged to argue for No single simple procedure for resolving interpretive issues exists No single simple procedure for establishing interpretive claims as premises in an argument exists To evaluate it Consider the best arguments that can be made for and against the claim Weigh up the arguments and the evidence on all sides Invitation to Critical Thinking Chapter 10

Invitation to Critical Thinking Chapter 10 Consistency of Claims Consistency is crucial to our understanding of deductive validity, but because inconsistency is always a sign that something is wrong somewhere. If a given set of claims as a group is internally inconsistent, then although you may not know which of the premises is false, you know they can't all be true. Invitation to Critical Thinking Chapter 10

Implications of Claims If a claim leads by implication to any further claim that is self-contradictory, or otherwise absurd or known to be false, then there is good reason to doubt the claim. This strategy has traditionally been known by its Latin name Reductio ad Absurdum (which means to reduce to absurdity). The strategy can also be inverted to use in defense of a position. Invitation to Critical Thinking Chapter 10