BS3916 Thinking about Management

1. BS3916 Thinking about Management 2. Some Principles of Logic

2. BS3916 Thinking about Management2: Some principles of Logic • Termsa word or combination of words that can stand by itself as the subject or predicate of a proposition • Silence is Golden (Both are terms)

3. BS3916 Thinking about Management 2: Some principles of Logic • Propositionthat which can be affirmed or deniede.g. Silence is Golden • Silence is the subject • Golden is the predicate

4. BS3916 Thinking about Management 2: Some principles of Logic • Argumentis a series of logically related propositions • All men are mortal (Major premise) • Socrates was a man (Minor premise) •  Socrates was mortal (Conclusion)

5. BS3916 Thinking about Management 2: Some principles of Logic • DEDUCTION (from the general to the particular) • If the premises are true and the argument is valid then the argument must be true • All of the information is contained (at least implicitly) in the premises

6. BS3916 Thinking about Management 2: Some principles of Logic • INDUCTION (inference of a general condition from a set of observed instances) • If the premises are true then the conclusion is probably but not necessarily true • The conclusion contains information not present, even implicitly, in the premises

7. BS3916 Thinking about Management 2: Some principles of Logic • TRUTHconcerns the factual correctness or otherwise of the premises • VALIDITY refers to whether the conclusion is correctly drawn (according to the rules of logic) from the premises • Propositions are true or false; arguments are valid or invalid (these terms are not inter-changeable)

8. BS3916 Thinking about Management 2: Some principles of Logic • Deductive logic is concerned with the construction of rules for the production of valid arguments (and the exposure of invalid ones) • NB an invalid argument might have a true conclusion (making it harder to spot) and a valid argument might have a false conclusion

9. BS3916 Thinking about Management 2: Some principles of Logic • Valid and true All cats have four legs My pet is a cat  my pet has four legs • Invalid and true The industrious are prudent Ants are prudent Ants are industrious

10. BS3916 Thinking about Management 2: Some principles of Logic • Valid and false All fish are cold-blooded Whales are fish Whales are cold-blooded • Invalid and false All cats have tails My hamster has tail My hamster is a cat

11. BS3916 Thinking about Management 2: Some principles of Logic • Construct two arguments…. • One which is valid but has a false conclusion • One which is invalid but in which all of the prepositions are true

12. BS3916 Thinking about Management 2: Some principles of Logic • IF-THEN • Affirming the antecedent (VALID) If (and only if) p, then q p q • Denying the Consequent (VALID) If (and only if) p, then q Not q not p

13. BS3916 Thinking about Management 2: Some principles of Logic • IF-THEN • Affirming the consequent (INVALID) If p, then q q p • Denying the Antecedent (INVALID) If p, then q Not p not q

14. BS3916 Thinking about Management 2: Some principles of Logic IF and IFF • IF is an ambiguous word…. • (a) If I pass my exams, I will be a graduate • (b) If I win the pools, I will become rich • In (a) IF means if and only if (sometimes Iogicians call this IFF) • In (b), there are are other ways of becoming rich (e.g. by inheritance)

15. BS3916 Thinking about Management 2: Some principles of Logic SOME and ALL • English is imprecise .. When we say All cats are mammals we are really saying… • All cats are (some of the entire category) of mammals

16. BS3916 Thinking about Management 2: Some principles of Logic Contradictions… • To deny that All cats are mammals we do not go to the opposite extreme and say No cats are mammals • The existence of one, egg-laying cat is sufficient for us to argue that Not all cats are mammals without going to the opposite extreme of saying No cats are mammals

17. BS3916 Thinking about Management 2: Some principles of Logic SYLLOGISMS • Are a triad of connected propositions that have to follow the rules of logic. • When these rules are broken, we have examples of fallacies

18. BS3916 Thinking about Management 2: Some principles of Logic Fallacy of the undistributed middle • All followers of Tony Blair love opera • I am a lover of opera • Therefore I am a follower of Tony Blair

19. BS3916 Thinking about Management 2: Some principles of Logic Fallacy of the illicit process • Some clever men are eccentric • Smith is not eccentric • Therefore Smith is not a clever man

20. BS3916 Thinking about Management 2: Some principles of Logic Fallacy of the Two Middle Terms • Chalk is different from cheese • Cheese is different from butter • Therefore butter is different from chalk

21. BS3916 Thinking about Management 2: Some principles of Logic Valid argument form: Reductio ad absurdum • To prove: p • Assume not-p • Deduce a false statement • Conclude that if not-p is false, then p must be true • Used extensively in mathematics where it is known as indirect proof

22. BS3916 Thinking about Management 2: Some principles of Logic Valid argument form: The dilemma • Either p or q • If p, then r • If q, then s • Either r or s

23. BS3916 Thinking about Management 2: Some principles of Logic Theological example • There is evil in the world • Either God cannot prevent evil or he does not wish to • If God can’t prevent evil, he is not all-powerful • If God does not want to prevent evil, he is not benevolent • Therefore God is not all powerful or he is not benevolent

24. BS3916 Thinking about Management 2: Some principles of Logic Fallacies of Deduction Affirming the Consequent • If p then q; q;  p • If we play good football, we will win • We have won • Therefore we played good football

25. BS3916 Thinking about Management 2: Some principles of Logic Fallacies of Deduction Denying the antecedent • If p then q; not p;  not q • If Jeffrey Archer testifies, he is innocent • Jeffrey Archer is not willing to testify •  Jeffrey Archer is not innocent

26. BS3916 Thinking about Management 2: Some principles of Logic Fallacies of Induction Insufficient statistics • Every cat I have seen has a tail •  all cats have tails

27. BS3916 Thinking about Management 2: Some principles of Logic Fallacies of Induction Biased statistics • Every time, I wait for a bus there are always buses going in the opposite direction • Therefore there are always more buses going in the opposite direction

28. BS3916 Thinking about Management 2: Some principles of Logic Causal fallacies Post hoc, ergo propter hoc • B was caused by A because B followed A

29. BS3916 Thinking about Management 2: Some principles of Logic Causal fallacies Confusion of cause and effect • Sober students have money • Drunk students have no money •  give drunk students money to make them sober

30. BS3916 Thinking about Management 2: Some principles of Logic Causal fallacies Common cause • When it’s cold, I put on warm clothes • When it’s cold, I catch a cold •  Warm clothes give me a cold

31. BS3916 Thinking about Management 2: Some principles of Logic Equivocation • Only man has a sense of humour • No man is a woman • No women have a sense of humour

32. BS3916 Thinking about Management 2: Some principles of Logic Petitio Principii (lit. Asking for the Principle Or ‘Begging the Question’) Assuming what we should be trying to prove but is this true in this case ? • All true pleasures lead to happiness • All unselfish acts are true pleasures •  all unselfish acts lead to happiness

33. BS3916 Thinking about Management 2: Some principles of Logic Exercises (1 of 6) • If the Tories win the next by-election, they will win the general Election • If they lose the by-election, it follows they will not win the General Election

34. BS3916 Thinking about Management 2: Some principles of Logic Exercises (2 of 6) • Since no monetarists were Keynesians and Margaret Thatcher was not a Keynesian, then Margaret Thatcher was a monetarist

35. BS3916 Thinking about Management 2: Some principles of Logic Exercises (3 of 6) • An increase in the money supply leads to inflation • So the way to cure inflation is to curb the money supply

36. BS3916 Thinking about Management 2: Some principles of Logic Exercises (4 of 6) • All BAMBA students work hard • All students who work hard pass their examinations •  All BAMBA students will pass their examinations

37. BS3916 Thinking about Management 2: Some principles of Logic Exercises (5 of 6) • BAMBA students who hate logic are intelligent • BAMBA students who hate logic will not fail their exams • As those who are not intelligent fail their exams

38. BS3916 Thinking about Management 2: Some principles of Logic Exercises (6 of 6) • Marx’s theories cannot be taken seriously since his prediction that there would be an increasing degree of polarisation and concentration into opposing classes is ridiculous