Reasoning & Decision Making

1. Reasoning & Decision Making Monty Python The Search for the The Holy Grail: Witch Scene http://www.youtube.com/watch?v=yp_l5ntikaU

2. The folly of mistaking a paradox for a discovery, a metaphor for a proof, a torrent of verbiage for a spring of capital truths, and oneself for an oracle, is inborn in us. -- Paul Valery

3. Reasoning & Decision MakingBackbone of Problem Solving & Creativity • Logic • Decision making

4. Reasoning, Decision Making and Problem solving • Logic • As you have noticed by now, there is very little that is logical about how the brain processes information. So, it will not surprise you that we have problems with doing logic. • Decision making

5. Test  for Reasoning Four ( 4 )  questions and a bonus question. You have to answer them instantly. You can't  take your time, answer all of them immediately .   Let's  find out just how clever you really are....

6. First  Question You  are participating in a race. You overtake the second person. What position are  you in? Answer: If you answered that  you are first, then you are absolutely wrong! If you overtake the second  person and you take his place, you are second! Try not to screw up  next time.

7. Second  Questiondon't take as much time as  you took for the first question, OK ? If you overtake the  last person, then you are...? Answer: If you answered that  you are second to last, then you are wrong again. Tell me, how can you  overtake the LAST Person? You're  not very good at this, are you?

8. Third  Question Very tricky  arithmetic! Note: This must be done in your head  only .Do NOT use paper  and pencil or a calculator. Try it… Take  1000 and add  40 to it. Now add another  1000. Now add  30. Add another  1000. Now add  20. Now add another  1000. Now add  10. What is the  total? Did you  get 5000? The correct answer  is actually 4100. If you  don't believe it, check it with a calculator! Today is definitely not your  day, is it?

9. Fourth Question Mary's father has  FIVE daughters: Nana, Nene, Nini, Nono. What is the name of  the fifth daughter? Did  you Answer Nunu?NO! Of course it  isn't.Her name is Mary. Read the question  again!

10. Bonus Question A mute person goes into  a shop and wants to buy a toothbrush. By imitating the action of brushing his  teeth he successfullyexpresses himself to the shopkeeper and the purchase  isdone. Next, a blind man comes into the shop who wants to buy a pair  ofsunglasses; how does HE indicate what he  wants? He just  has to open his mouth and ask.... It's really  very simple…  

20. If, then statements • If, then statements = conditional logic • If the first part of a statement is true then the second part must also be true If it rains the street gets wet It rained The street gets wet Is this a valid or invalid conclusion? -valid! 1

21. If, then statements p q If it rains then the street gets wet It rained The streets get wet Antecedent Consequent If p, Then q

22. If, then statements If it rains, then the streets get wet. It doesn’t rain. Therefore, I conclude that the streets don’t get wet. This argument is valid This argument is invalid 2

23. If, then statements If it rains, then the streets get wet. The streets are not wet. Therefore, I conclude that it has not rained. This argument is valid This argument is invalid 3

24. If, then statements If it rains, then the streets get wet. The streets are wet. Therefore, I conclude that it must have rained. This argument is valid This argument is invalid 4

25. If, then statements If p, then q. I observe p. Therefore, I conclude that q must be the case. This argument is valid This argument is invalid 5

26. If, then statements If p, then q. I don’t observe p. Therefore, I conclude that q is not the case. This argument is valid This argument is invalid 6

27. If, then statements If p, then q. I don’t observe q. Therefore, I conclude that p must not be the case. This argument is valid This argument is invalid 7

28. If, then statements If p, then q. I observe q. Therefore, I conclude that p must be the case. This argument is valid This argument is invalid 8

29. p q If, then statements If it rains, then the streets get wet. It rains. Therefore, the streets gets wet. p q

30. If, then statements • Tree Diagrams • Critical information represented along “branches”. • Help to determine validity of a statement If it rains, then the streets get wet It rains Therefore the streets get wet

31. If, then statements p q it rains the streets get wet if the streets don’t get wet ~p it doesn’t rain ~q the streets get wet • If it rains, then the streets get wet • It rains • Therefore the streets get wet • AFFIRMING THE ANTECEDANT: VALID q

32. p q If, then statements If it rains, then the streets get wet. It rains. Therefore, the streets gets wet. p q Valid! Consequent Antecedent Affirming the antecedent If p, then q.

33. If, then statements If p, then q. I don’t observe p. Therefore, I conclude that q is not the case. 6 If it rains, then the streets get wet. It doesn’t rain. Therefore, I conclude that the streets don’t get wet. This argument is valid This argument is invalid 2 Denying the antecedent

34. If, then statements p q it rains the streets get wet if the streets don’t get wet ~p it doesn’t rain ~q the streets get wet • If it rains, then the streets get wet • It doesn’t rain • Therefore I conclude that the streets don’t get wet • DENYING THE ANTECEDENT: INVALID q

35. If, then statements If p, then q. I don’t observe q. Therefore, I conclude that p must not be the case. 7 If it rains, then the streets get wet. The streets are not wet. Therefore, I conclude that it has not rained. This argument is valid This argument is invalid 3 Denying the consequent

36. If, then statements p q it rains the streets get wet if the streets don’t get wet ~p it doesn’t rain ~q the streets get wet • If it rains, then the streets get wet • The streets are not wet • Therefore I conclude that it has not rained • DENYING THE CONSEQUENT: VALID q

37. If, then statements If p, then q. I observe q. Therefore, I conclude that p must be the case. 8 If it rains, then the streets get wet. The streets are wet. Therefore, I conclude that it must have rained. This argument is valid This argument is invalid 4 Affirming the consequent

38. If, then statements p q it rains the streets get wet if the streets don’t get wet ~p it doesn’t rain ~q the streets get wet • If it rains, then the streets get wet • The streets are wet • Therefore I conclude that it must have rained • AFFIRMING THE CONSEQUENT: INVALID q

40. E K 4 7 “If a card has a vowel on one side, then it has an even number on the other side” Which cards do you need to turn over to test the validity of the rule?

41. Wason (1966) Selection Task E K 4 7 “If a card has a vowel on one side, then it has an even number on the other side”  If p, then q Answer: p ~p q ~q p ~p q ~q Affirming the antecedent Denying the antecedent Affirming the consequent Denying the consequent E K 4 7

42. If, then statements p q vowel even number if odd number ~p consonant ~q even number q

43. Griggs & Cox (1982) • If a person is drinking beer, then the person must be over 21 Drinking beer Drinking Coke 16 years of age 22 years of age p q ~p ~q

44. If, then statements p q drinks beer older than 21 if younger than 21 ~p drinks coke ~q older than 21 q

45. Griggs & Cox (1982) • If a person is drinking beer, then the person must be over 21 Drinking beer Drinking Coke 16 years of age 22 years of age p q ~p ~q

46. If, then statements p q drinks beer older than 21 if younger than 21 ~p drinks coke ~q older than 21 q

47. Griggs & Cox (1982) • If a person is drinking beer, then the person must be over 21 Drinking beer Drinking Coke 16 years of age 22 years of age p q ~p ~q

48. If, then statements p q drinks beer older than 21 if younger than 21 ~p drinks coke ~q older than 21 q

49. Griggs & Cox (1982) • If a person is drinking beer, then the person must be over 21 Drinking beer Drinking Coke 16 years of age 22 years of age p q ~p ~q

50. If, then statements p q drinks beer older than 21 if younger than 21 ~p drinks coke ~q older than 21 q