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Flaws in Arguments (1)

Flaws in Arguments (1). Critical Thinking D Gray Feb 2007 Updated September 2009. Post Hoc fallacy. Post hoc ergo propter hoc “After this, therefore because of this.” X occurs before Y Therefore X is the cause of Y Causality Sequential Coincidence Superstition. Post Hoc fallacy.

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Flaws in Arguments (1)

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  1. Flaws in Arguments(1) Critical Thinking D Gray Feb 2007 Updated September 2009

  2. Post Hoc fallacy • Post hoc ergo propter hoc • “After this, therefore because of this.” • X occurs before Y • Therefore X is the cause of Y • Causality • Sequential • Coincidence • Superstition

  3. Post Hoc fallacy Walking under a ladder … Early to bed, early to rise, … Lucky rabbit’s foot Your sins will find you out. Watching television gives you square eyes. Watching violence on TV causes violence in young people. My alarm goes off at 5 am and the Sun rises shortly afterwards. Therefore my alarm causes the sun to rise. Good exam results lead to happiness.

  4. Ad Hominem fallacy • “Against the man” • Person X makes a claim • Person Y attacks the character of Person X • Person Y concludes that Person X’s claim is therefore false. • Attacking personality • Historical context • Reputation • Credibility

  5. Ad Hominem fallacy • Look for: • Attacks on the person, not the opinion. • Ignoring the argument • Talk about past reputation or character

  6. Ad Hominem fallacy • Political debates • Family arguments • Interviews on the news • Racism, sexism, homophobia etc…

  7. Why are these examples of Post Hoc fallacies? Breaking a mirror leads to seven years bad luck. Finding a four leaf clover brings good luck A black cat crossing your path brings bad luck

  8. Post Hoc fallacy? In Copenhagen, in Denmark, some people believe that the more storks that nest in the city, the more human babies are born. They point to the fact that during the 12 years following WW2, the more storks that nested in Copenhagen in the Spring, the more babies were born in the year.

  9. Post Hoc fallacy? Many people warned that the liberalisation of drink laws, which allowed pubs and clubs to extend drinking hours, would fuel disorder. However, the few months after their introduction, serious violent crime has fallen 21% - and it is down twice that in some towns. Also, there were 14% fewer woundings in the same period. This shows that the new licensing laws have resulted in less violent crime.

  10. Ad Hominem Write a short Ad hominem argument as to why: • Wayne Rooney should not be England football captain. • Sophie should not have won BB9 • Gordon Brown should not be prime minister • Freddy Flintoff should not be England cricket captain • Oasis should stop touring

  11. Straw man fallacy • Straw targets are easier to knock down • Person X presents an argument • Person Y represents the argument in a distorted fashion • Person Y then refutes the argument • This undermines the original argument of Person X • Misrepresentation • Refute • Ridicule • Exaggerate

  12. Straw man fallacy • Ridiculous! • Wild! • Ludicrous! • Absurd! • Unbelievable! • Stupid!

  13. Tu quoque fallacy • “You too” or “You also” • Do as I say, not as I do! • Person A makes a claim • Person B asserts that A’s actions or past claims are inconsistent with the claim • Therefore the claim is false

  14. Tu quoque fallacy Rejecting an argument because of what the person does, not because of the strength of the argument. Seeking to retain the status quo Anti-Smoking Staying out late Speeding on a motorway White lies Everyone does it

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