Reason

1. Reason

2. What is reason? • Discuss. • Try to give a definition: • In which subjects is reason most important?

3. Reason in practice • I know because I thought about it…. • Complete A little Comprehension Exercise • Answer on own • Discuss in pairs, small groups • Reflect on your experience of the exercise

4. Deductive Reasoning • From the general to the specific • Can use syllogisms eg: • All IB subjects are awesome PREMISE • ToK is an IB subject PREMISE • Therefore ToK is awesome CONCLUSION • No mammals have gills PREMISE • Sharks have gillsPREMISE • Therefore sharks are not mammalsCONCLUSION TASK: • Try to write three syllogisms of your own. • Are these arguments true?

5. Syllogisms and Venn diagrams • Some IB subjects are awesome PREMISE • ToK is an IB subject PREMISE • Therefore ToK is awesome CONCLUSION TASK: • Use Venn diagrams to prove the truth of your own syllogisms • Write an untrue syllogism and use your Venn diagram to prove it

6. Enthymemes • In regular speech you don’t generally say syllogisms • Enthymeme: syllogism with implied premise • E.g. Nancy goes to Cambridge so she isn’t poor • Poor people can’t go to Cambridge • Nancy goes to Cambridge • Nancy is not poor TASK: • Write you own enthymemes.

7. Deductive Reasoning Review: • Use a Venn diagram to help resolve the following syllogism: • All zerks are zorks • Some zorks are zarks • Therefore some zerks are zarks • Write out the syllogism implied by the following enthymeme: • Global warming is a major issue, it should be dealt with urgently

8. Inductive Reasoning • From the specific to the general • Essentially ‘generalisations’ • Underpins much of human knowledge

9. Some Problems: • The hasty generalisation: • A generalisation made too quickly – jumping to conclusions • Confirmation bias: • We generalise more readily when the generalisation backs up our preconceptions TASK: • Write down three hasty generalisations you have made • Can you think of any times you have suffered from confirmation bias?

10. Inductive Reasoning and Race • Inductive reasoning is the cause of racism and racialist thinking. • What is a Chinese person like?

11. Cont….. • The problem is that race does not exist!

12. Where on my journey do people stop being white?

13. Inductive Reasoning and Language • Words are generalisations? TASK: • Try to imagine living a day in which you made no generalisations (of any kind).

14. What Makes a Good Generalisation? • Number • Variety • Exceptions • Coherence • Subject Area • TASK: • Which of your subjects is most and least dependent on inductive reasoning? • Do the generalisations made in your subjects pass the test of a ‘good’ generalisation

15. Inductive vs Deductive • Which leads to greater certainty?

16. Logical Fallacies • When reasoning in practice, people don’t talk in syllogisms. • Here are some of the mistakes we often make….

17. Special Pleading • Viewing yourself and your own circumstances as special and worthy of special consideration • Of course you shouldn’t push into the lunch queue but I have to complete a homework whereas these other fools don’t • Have you ever done this? Give examples.

18. Ad Hominem • ‘Against the man’ • Playing the player not the game • In politics do you: • Logically argue against your opponents policies? • Do you question the credibility of your opponent?

19. Circular Reasoning • God exists because the Bible say She does, and we can trust the Bible because it was written by God. • What is the flaw in this argument? • Can you think of other examples?

20. Post hoc ergo procter hoc • It is fact that in America, the cities with more churches also have more prostitutes. • Why?

21. Post hoc ergo procter hoc • Both depend on size • I.e. don’t mistake correlation for cause

22. False Analogy • Drawing inappropriate comparisons • Nails hold a house together just as employees hold a business together. Similarly, like nails, employees only work if you hit them on the head. • Try to think of your own false analogies (sayings and proverbs are a rich source of these).

23. Loaded Questions • A question with a built in assumption: • When did you stop beating your wife? • Do you always cheat in exams? • Try to develop your own.

24. Argument ad Ignorantium • Claiming something is true because there is nothing to disprove it. • As communist witch-hunter Joe McCarthy once said: • ‘There is nothing in this man’s files to prove he isn’t a communist’ • Can you think of any common beliefs based on this type of argument?

25. Equivocation • Arguments depending on dual meanings of words • Chocolate is better than nothing • Nothing is better than good health • Therefore chocolate is good for your health. • Try to think of an example of your own.

26. False Dilemna • Falsely assuming that only two alternatives exist • Do those who want to raise taxes really want to see the economy suffer? • Can you think of any?

27. In fours • Write a 2-3 minute speech on a topic of your choice but try to discreetly load it with as many logical fallacies as possible.