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  • 1. • When Claims Conflict  Contradictions - If a claim conflicts with other claims we have good reason to accept, we have good grounds for doubting it.  If a claim conflicts with our background information, we have good reason to doubt it. Chapter 4: Reasons for Belief and Doubt
  • 2. Fact and Opinions • Two meanings of “fact” – State of affairs – Claims that is true • “That’s a matter of opinion” – There are many different opinions about this issue – There is no objective fact of the matter as the grounds for deciding are entirely subjective
  • 3. • Belief and Evidence  We should proportion our belief to the evidence.  It’s not reasonable to believe a claim when there is no good reason for doing so.
  • 4. • Experts and Evidence  If a claim conflicts with expert opinion, we have good reason to doubt it.  Who is an expert?  Access to more information on the subject than we do  They are better at judging that information than we are.
  • 5. When to rely on experts • When they are experts in the relevant field • When the are speaking or writing on their subject of expertise • When there is not some reason to doubt their motivation • When experts agree
  • 6. • When the experts disagree about a claim, we have good reason to doubt it.
  • 7. Appeal to authority • When any of the previous conditions is violated the fallacy of appeal to authority is committed. • The reliance on expert opinion is undermined.
  • 8. Some hints that the authority is dubious • The expert is guilty of simple factual or formal errors. • The expert’s claims conflict with what we have good reason to believe. • The expert does not adequately support his or her assertions. • The expert’s writing contains logical contradictions or inconsistent statements • The expert is strongly biased, emotional, or dismissive. • The expert relies on information you know is out of date. • The other experts in the same field disagree.
  • 9. •Personal Experience •It’s reasonable to accept the evidence provided by personal experience only if there’s no good reason to doubt it. • Factors that can give us good reason to doubt the reliability of personal experience:  Impairment  Expectation  Innumeracy
  • 10. Impairment • Memory – We construct our memories • Perception – We sometimes see what we want to see – the constructive nature of perception
  • 11. Expectation • Experiments showing that if we are told that something is going to happen we will experience it • Pareidolia • Stereotypes and perceptions: racism/sexism/prejudice
  • 12. Innumeracy • We (humans) are bad at making judgments about probabilities. • We frequently make misjudgments about coincidences. • Gambler’s fallacy So what conclusion should we draw from this? Don’t rely solely on our intuitions.
  • 13. Fooling ourselves • Resisting contrary evidence • Looking for confirming evidence • Preferring available evidence
  • 14. Resisting contrary evidence • We may deny, ignore, or reinterpret evidence that contradicts cherished beliefs.
  • 15. Looking only for confirming evidence • Confirmation bias • Popper’s point about confirmation – what makes a theory scientific
  • 16. Preferring available evidence • Availability error – Not just what is readily available in the sense of easy to find, but also what is psychologically available. – Weighting what you have seen or experienced more heavily than it should be weighted – Hasty generalization
  • 17. • How to evaluate the reliability of the news:  Consider whether the report conflicts with what you have good reason to believe.  Look for reporter slanting.  Consider the source.  Check for missing information.  Look for false emphasis.  Check alternative news sources.
  • 18. Advertising and persuasion • We generally have good reason to doubt advertising claims and to be wary of advertising’s persuasive powers. – The purpose of advertising is to sell or promote something. – History of misleading messages
  • 19. Identification • Snob appeal – Ads asking you to identify with particular groups of people – Insinuating that you will be identified with such people if you….
  • 20. Slogans • Catch phrases get our attention
  • 21. Misleading comparisons • Vagueness of comparisons • What’s the baseline with which we are comparing? • Emptiness of claims • Comparing “apples and oranges”
  • 22. Weasel words • Words which appear to make a strong claim but are really close to lying • Taking back what was said with modifiers that undermine the claim