Thought experiment Arguments

1. Thought experiment Arguments 1

2. Thought experiments are devices of the imagination used to investigate the nature of reality (including physical, psychological, and social/ethical). • They have been used in natural sciences, social sciences, history, mathematics, and philosophy. 2

3. Why use thought-experiment? • Real experiments may be very time-consuming and expensive. • Real experiments may be unethical. • Real experiments may be physically impossible.

4. ECONOMICS 4

5. The demand-supply model is the product of thought experiment (rather than empirical studies). 5

6. Based on this model, we can explain and predict the relation between price and quantity of a product (or the inflation rate and GDP of a country). 6

7. PHYSICS 7

8. Aristotle: the heavier a body is, the faster it falls. • Galileo: all things fall with the same speed (or acceleration). 8

9. Galileo’s Thought Experiment A B A+B 9

10. Assume that Aristotle is right. • B falls faster than A. • How fast will (A+B) fall? • Ans1: (A+B) will fall faster than B because (A+B) is heavier than B. • Ans2: (A+B) will fall slower than B because A will act as a “brake” on B. • Ans1 contradicts with Ans2. • Therefore, Aristotle must be wrong. 10

11. Ethics: Causal responsibility 11

12. Which statement is true? • A person is morally responsible for an event because she is the cause of it. • A person is the cause of an event because she is morally responsible for it.

13. Suppose that a building is on fire and a fireman is asked what is the (primary) cause of the fire. • His answer may include: a short circuit, someone’ having smoked on bed, an overheated transformer, etc. • Under normal situation, his answer will NOT include the presence of oxygen. 13

14. Although the presence of oxygen is a necessary cause, it is not a salient cause. • When we are asked what causes an event, we are asked about the salient causes. • In normal situations, either we have already known that the presence of oxygen causes fire or we are not interested in knowing this cause. • Hence, what makes a cause a salient cause depends on our interest. 14

15. When we ask who causes an event, we are interested in finding out who is morally responsible for the event. • I.e., who is morally responsible for the event is the salient cause. • We can use thought experiments to support this point. 15

16. A thought experiment • Jack made a bomb parcel and mailed it at a post office. A postman delivered the parcel to Paul’s home. Paul opened the parcel and was blown up into pieces. • Who caused Paul’s death? 16

17. Jack, the postman, and Paul all are involved in the causal chain resulting in the death of Paul: • If Paul had not opened the parcel, he would not have been killed. • If the postman had not delivered the parcel, Paul would not have been killed. • If Jack had not mailed the parcel, Paul would not have been killed. • However, since only Jack is morally responsible for Paul’s death, we think that only he is the cause. 17

18. Another thought experiment • Nancy and Jane work for the same company. • They each need to use a central computer for work sometimes. • The computer is very old. If two people are logged on at the same time, it usually crashes. 18

19. The company has instituted a policy: Nancy would be the only one permitted to use the computer in the mornings; Jane would be the only one permitted to use the computer in the afternoons. • One day Nancy logged on the computer at 9am. • Jane disobeyed the policy and also logged on at 9am. • The computer crashed immediately. • Who caused the computer to crash? 19

20. Both Nancy and Jane caused the computer to crash. • The cause is a conjoint cause. • We think Jane rather than Nancy caused the crashing because we think Jane acted wrongly. • That is, Jane’s having acted wrongly renders her action a salient cause. 20

21. conclusion • A person is the (salient) cause of an event because he is morally responsible for it.

22. Ethics: Moral permissibility 22

23. does the moral permissibility of an action depend on consequences only? • The Split Track Case • Suppose a trolley is heading towards 6 people who are trapped on the main track. • It is morally permissible to divert the trolley into a side track on which a person is trapped so that the six will be saved and the one will be killed. 23

24. The Bridge Case • It is morally impermissible to push a fat man from a bridge into the trolley in order to stop it from heading towards the 6 people. 24

25. Note that the consequences of this action are the same as those of redirecting the trolley in the Split Track Case. • http://www.youtube.com/watch?v=6WB3Q5EF4Sg

26. Empirical results

27. Conclusion • The moral permissibility of an action depends on things other than consequences. • What are they?

28. 2 possible answers • Intention Theory • The moral permissibility of an action also depends on the action’s intention. • Intending evil (i.e., intending to involve someone in an activity that is harmful to her) is wrong. • In the Split Track case, the hit on the victim is only a side-effect; the agent does not intend the hit • In the Bridge case, the agent intends the hit on the victim (the evil) as a means to save the five. • Therefore, it is wrong to push the fat guy.

29. Causal Sequence Theory • The moral permissibility of an action also depends on the causal relation of the action’s consequences. • Assuming that an action results in more good than evil, it is still wrong if the evil causes the good. • In the Split Track Case, the hit on the victim (the evil) is not causally necessary to save the five (the good). • Therefore, diverting the trolley is not wrong.

30. In the Bridge Case, the hit on the victim causes the trolley to halt, and thereby saves the five. • Therefore, pushing the fat guy is wrong.

31. WHICH THEORY IS TRUE? • The moral permissibility of an action depends on its rationally expected consequences. • Actions motivated by bad intention usually have bad expected consequences. • Actions motivated by good intention usually have good expected consequences. • Therefore, the permissibility of an action depends derivatively on it intention. • This can be shown by the following thought-experiment.

32. Thought experiment 1 • Suppose that Andrew gave a peanut butter sandwich to a starving person and he died after eating the sandwich because he was allergic to peanuts. • Scenario 1: Andrew believed that the starving person was allergic to peanuts and intended to kill him. • Andrew’s action has good consequences only if he mistakenly believed that the starving person had the allergy. • Thus, his action has bad expected consequences. • Therefore, his action is wrong.

33. Scenario 2: Andrew did not know that anyone was allergic to peanuts, and his ignorance is not due to his fault. • Andrew’s action has bad consequences only in rare cases. • Thus, his action has good expected consequences. • Therefore, his action is right. • But we want to know whether the permissibility of an action depends fundamentally on its intention? • In order to answer this question, we need to answer the following questions.

34. Question • Some actions having good expected consequences can be motivated by bad intention. • Are they wrong?

35. Thought experiment 2 • I give several coins to a charity-flag seller. • My action has good expected consequences. • However, my intention is to make her collection bag heavier so that she will find more difficult to carry the bag. • Is my action wrong?

36. Question • Some actions fulfilling the agent’s duties can be motivated by bad intentions. • Are they wrong?

37. Thought experiment 3 Your class presentation is poor. I inform you honestly. I am fulfilling the duty of a teacher. My intention is to humiliate and discourage you. Is my action wrong?

38. A Challenge to the Intention theory • If the moral permissibility of an action depends on its intention, the same action may be permissible for A to do but impermissible for B to do.

39. Thought experiment 4 • A patient with painful terminal cancer requests a doctor to withdraw her respirator to let her die. • Doctor A is willing to do so in order to prevent her from suffering unnecessarily. • Doctor B is also willing to do so because he thinks that this patient is too annoying and is happy to get rid of her. • If the permissibility of an action depends on its intention, we have to say that Doctor A is permissible to withdraw the patient’s respirator but Doctor B is not.

40. A Challenge to the Causal sequence theory • Intention is intuitively morally relevant, but casual sequence of action’s consequences is not. • We need to ask why causal sequence is relevant to whether an action is morally permissible or not.

41. conclusion • We still do not which theory is correct.