Business Thinking

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Business Thinking

• Some Principles of Logic

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Business ThinkingAPEL 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)

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Business Thinking APEL Some principles of Logic

• Propositionthat which can be affirmed or
  deniede.g. Silence is Golden
• Silence is the subject
• Golden is the predicate

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Business Thinking APEL 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)

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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)

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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 a tail? My hamster is a cat

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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)

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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 cant 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL Some principles of Logic

• Fallacies of Induction
• Insufficient statistics
• Every cat I have seen has a tail
• ? all cats have tails

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Business Thinking APEL 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

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Business Thinking APEL Some principles of Logic

• Causal fallacies
• Post hoc, ergo propter hoc
• B was caused by A because B followed A

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Business Thinking APEL 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

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Business Thinking APEL Some principles of Logic

• Causal fallacies
• Common cause
• When its cold, I put on warm clothes
• When its cold, I catch a cold
• ? Warm clothes give me a cold

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Business Thinking APEL Some principles of Logic

• Equivocation
• Only man has a sense of humour
• No man is a woman
• No women have a sense of humour

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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

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Business Thinking APEL 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
  

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Business Thinking APEL 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

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Business Thinking APEL Some principles of Logic

• Exercises (6 of 6)
• Marxs theories cannot be taken seriously since
  his prediction that there would be an increasing
  degree of polarisation and concentration into
  opposing classes is ridiculous