1. Informal Reasoning 1/9

2. Agenda  Introduce Informal Reasoning  Reflect on Informal Reasoning  END GOAL: Is informal reasoning reliable?

3. Question 1 What is the difference between a prejudice, a generalization, and a scientific law?

4. Informal Reasoning  Post hoc ergo hoc  Ad hominem  Circular Reasoning  Special Pleading  Equivocation  Ad Ignorantiam  False Analogy  False Dilemma  Hasty Generalization  Loaded Questions

5. Post hoc ergo propter hoc  Literally, “after this, therefore on account of this”  Because one thing (b) follows another thing (a), then A must be the cause of B.  EXAMPLE:  Murder rate goes up after abolition of the death penalty. Therefore, getting rid of the death penalty increased the murder rate.  FLAW: it COULD be the case, but it might not be

6. Post hoc ergo propter hoc  Even when one event USUALLY follows another, it is still does not NECESSARILY mean the two are connected.  CAREFUL: claiming something is a fallacy when not  Tobacco Company  Casual Connection vs. Fallacy (red wine and heart)

7. Ad hominem  Literally: “Against the man”  Attack/Support the person rather than the argument (VESTED INTEREST)  Rather than critique an idea or argument, a person is being attacked  USUALLY used to attack someone, but can also be done to support….Einstein liked it, so it has to be good!

8. Question 2 Are we ever justified in rejecting what someone says solely on the basis of who they are?

9. Circular Reasoning  You assume the truth of something that you are supposed to be proving  What at first looks like an argument is really just a reassertion of their position  EXAMPLE: I know that Jesus is the Son of God because he said he was, and the Son of God would not lie.

10. Special Pleading  Double standard – making an exception in your own case that you would not find acceptable for someone else  Example: I know there is a drought and we need save water….but MY flowers are prize winning daffodils!

11. Equivocation  Syllogisms with different senses/meanings A hamburger is better than nothing Nothing is better than good health. Therefore a hamburger is better than nothing.  Two different definitions of nothing (not having anything vs. there is not anything)

12. Ad Ignorantiam  Something is true on the grounds that there is no evidence to disprove it  Loch Ness Monster  Bog Foot?

13. False Analogy  Assume that because two things are similar in one respect they must also be true in other ways  “Just as in time the gentle rain can wear down the tallest mountains, so, in human life, all problems can be solved by patience and quiet persistence.”

14. False Dilemma  The fallacy of deciding there are only two options, when in reality there are a wide range of possibilities  Do those who advocate an increase in military funding what to see schools and hospitals close?

15. Loaded Questions  A question that contains a built in assumption that has not been justified and may be false.  Do you always cheat on exams?  Can be a statement: That teacher was not drunk today.

16. Quote 1  “What’s so fascinating about New Yorkers is that each person has a whole lexicon of personal logic in the way that they decipher and do what has to be done to enjoy, stay alive, take pleasure in this place.” –Spalding Gray  What does this quote mean?  Is it true only of New Yorkers?

17. Quote 2  “When dealing with people, remember you are not dealing with creatures of logic, but creatures of emotion.” – Dale Carnegie  What does this quote mean?  Agree/Disagree?  How does this quote and your position on it affect your answer to yesterday question about perception vs. reasoning?

18. Quote 3  “All of our reasoning ends in surrender to feeling.” –Blaise Pascal  What does this quote mean?  Do you agree or disagree?  What are some examples you see in our society/in your own life?