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  1. 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. 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. 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. 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. 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. 6. • When the experts disagree about a claim, we have good reason to doubt it.
  7. 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. 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 • The expert relies on information you know is out of date.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. 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. 10. Impairment • Memory – We construct our memories • Perception – We sometimes see what we want to see – the constructive nature of perception
  11. 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. 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. 13. Fooling ourselves • Resisting contrary evidence • Looking for confirming evidence • Preferring available evidence
  14. 14. Resisting contrary evidence • We may deny, ignore, or reinterpret evidence that contradicts cherished beliefs.
  15. 15. Looking only for confirming evidence • Confirmation bias • Popper’s point about confirmation – what makes a theory scientific
  16. 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. 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. 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. 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. 20. Slogans • Catch phrases get our attention
  21. 21. Misleading comparisons • Vagueness of comparisons • What’s the baseline with which we are comparing? • Emptiness of claims • Comparing “apples and oranges”
  22. 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
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