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Theory of Knowledge Diagram Mathematics Ways of Knowing Natural Sciences Reason Sense Perception Ethics Knower(s) Emotion Areas of Knowledge Language Human Sciences Arts History
Empiricism starting point for all knowledge is experience Rationalism starting point for all knowledge is reason TaK - Reason
What is meant by ‘Reason’? • 1. Reason (noun) • a basis or cause, as for some belief, action, fact, event, etc • 2. Reason (verb) • to think or argue in a logical manner; • to form conclusions or judgments from facts, propositions or premises (initial assumptions) TaK - Reason
TaK - Reason There are three men on a train: one of them is an economist, one is a logician and one is a mathematician. They have just crossed the border into Scotland and they see a brown cow standing in a field from the window of the train. The cow is standing parallel to the train. The economist says, “Look! The cows in Scotland are brown”. The logician says, “No. There are cows in Scotland of which one, at least, is brown.” The mathematician says, “No. There is at least one cow in Scotland of which one side appears to be brown.”
TaK - Reason “He that will not reason is a bigot*; he that cannot reason is a fool; and he that dares not reason is a slave” William Drummond 1585-1649 *Bigot: a prejudiced person who is intolerant of any opinions differing from their own
TaK - Reason Reason enables us to go beyond the immediate evidence of our senses to acquire new knowledge The path is wet in the morning .... You left your mobile phone either on your desk or in your coat pocket ...
TaK - Reason A dead body is lying in a field. He is carrying an unopened package. How did he die?
Aristotle 384BCE – 322BCE TaK - Reason …. wrote that women have fewer teeth than men
TaK - Reason Gustave Le Bon 1841 - 1931 Social Psychologist Influential theorist about Crowd Psychology Influential writings about propaganda techniques
“… there are a large number of women whose brains are closer in size to those of gorillas than to the most developed male brains. This inferiority is so obvious that no one can contest it for a moment; only its degree is worth discussion. All psychologists who have studied the intelligence of women, as well as poets and novelists, recognize today that they represent the most inferior forms of human evolution and that they are closer to children and savages than to an adult, civilized man….” TaK - Reason
TaK - Reason Teacher A: Jenny is a great student. Although her assignments are always late, she always asks perceptive and intelligent questions in class Teacher B: Jenny is one of the worst students I’ve ever met. Her smart answers in class don’t make up for never getting assignments in on time
TaK - Reason Why is it better to have round manhole covers than square ones?
TaK - Reason • Three kinds of Reasoning • Deductive reasoning • Inductive reasoning • Informal reasoning
TaK - Reason The Curious Incident of the Dog in the Night-time .... Sherlock Holmes
TaK - Reason The Curious Incident of the Dog in the Night-time .... Gregory (Scotland Yard detective): "Is there any other point to which you would wish to draw my attention?“ Holmes: "To the curious incident of the dog in the night-time.“ Gregory: "The dog did nothing in the night-time.“ Holmes: "That was the curious incident.” • Watchdogs bark at strangers • The watchdog did not bark at the thief • Therefore the thief was not a stranger
TaK - Reason A murderer is condemned to death. He has to choose between three rooms: The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years. Which room is safest for him?
TaK - Reason Deductive reasoning From general to particular • All humans are mortal • Edmund is human • Therefore Edmund is mortal If the ‘assumptions’ are correct (which in Logic are called, ‘premises’) the conclusion has to follow. No if’s and but’s - it’s not a matter of personal opinion, nor is it affected by culture.
TaK - Reason Deductive reasoning From general to particular: • Two premises and a conclusion • Three terms – each occurring twice • Quantifiers (‘all’, ‘some’, ‘most’ etc) • This is formally called a Syllogism Term 1 Quantifier Term 2 • All humans are mortal • Edmund is human • Therefore Edmund is mortal Premise 1 Term 3 Premise 2 Conclusion
TaK - Reason Truth and Validity • Truth: concerned with what is the case • Validity: only concerned with whether conclusions follow from premises…..
TaK - Reason • All polar bears are footballers • Rinchen is a polar bear • Therefore Rinchen is a footballer • Valid – but not true • You should not say that an argument is true or false, but that it is valid or invalid.
TaK - Reason A man is wearing black. Black shoes, socks, trousers, coat, gloves and ski mask. He is walking down a back street with all the street lamps off. A black car is coming towards him with its lights off but somehow manages to stop in time. How did the driver see the man?
TaK - Reason There is a scene in a Broadway play where a guest at a party meets a Catholic priest. The guest asks, “Don’t you hear some terrible things in confession?” The priest replies, “Oh yes. In fact when i was just starting out as a priest, the first person who came to confession told me they had committed a murder.” Later on, a newcomer joins the party, and on being introduced to the priest says, “I met you a long time ago, Father. In fact I was the first person to come to you for confession.”
TaK - Reason Deductive reasoning From general to particular: • The first person who came to confession told the priest that he had committed a murder • The guest at the party was the first person to come to the priest for confession • Therefore the guest had committed a murder
TaK - Reason This is an unusual paragraph. I'm curious how quickly you can find out what is so unusual about it. It looks so plain you would think nothing was wrong with it. In fact, nothing is wrong with it! It is unusual though. Study it, and think about it, but you still may not find anything odd. But if you work at it a bit, you might find out.
TaK - Reason Factual disputes • If I think Singapore is south of the equator, and you say that it is north of the equator, our disagreement is easily resolved by reference to an atlas. Verbal disputes • This is where the presence of an ambiguous term conceals the fact that there is no real disagreement. As shown in the ‘bachelor’ example, the ambiguity can arise even with words in common use.
TaK - Reason Being careful in arguments: Definitions - Bachelor • Anthony is 17 years old . He attends school and lives with his parents. • Joe is 17 years old. He left home at 14 to start his own company and is now a millionaire. When not travelling around the world to attend business meetings he lives in his own house and has a playboy lifestyle. • Charlie and Chris are homosexual lovers who have been happily living together for 20 years. • David has been living with Sue for the last 10 years. They have 3 children. He has never been married and has no intention of ever getting married. • Jim is a married to a woman who paid him $50,000 so that she could become a citizen of his country. He has met her once, and they have never lived together. • Father Francis is a Catholic priest
TaK - Reason A: Dave is the best tennis player at the club. His serve is faster than anyone elses. B: No, Nick is much better! His volleying is amazing.
TaK - Reason A: National Inc. are doing well. Their sales so far this year are 15% up on last year. B: No, they aren’t doing very well. Profits so far this year are 30% lower than they were this time last year.
TaK - Reason A: That man just broke the law by driving like that. B: No he didn’t – that was perfectly legal
TaK - Reason Deductive reasoning From general to particular • All humans are mortal • Edmund is human • Therefore Edmund is mortal If the ‘assumptions’ are correct (which in Logic are called, ‘premises’) the conclusion has to follow. No ifs and buts - it’s not a matter of personal opinion, nor is it affected by culture.
TaK - Reason Inductive reasoning From the particular to the general (the observed to the unobserved) • This first bird can fly... • This second bird can fly... • This third bird can fly... • This fourth bird can fly... • This nth bird can fly... • Therefore all birds can fly.
TaK - Reason Science uses inductive reasoning: Formulates general laws on the basis of limited observations – • Metal A expands when heated • Metal B expands when heated • Metal C expands when heated • ..... a conclusion?
TaK - Reason Inductive reasoning From the particular to the general (the observed to the unobserved) • I have never heard of a human being who didn’t die • ... then we generalise to ... • All human beings are mortal • Inductive Reasoning allows us to make generalisations about the world.
TaK - Reason general Induction Deduction particular
TaK - Reason What is a generalisation? • What distinguishes good generalisations? • Number – you see one dog swimming... • Variety – different circumstances; old dogs, young dogs, different breeds... • Exceptions – find counter-examples... • Coherence – you should demand more evidence to support surprising claims than unsurprising ones • Subject area – eg. generalisations tend to be more reliable in the natural sciences than in the social sciences
I know you believe you understand what you think I said, but I am not sure you realize that what you hear is not what I meant.
A Story A businessman had just turned off the lights in the store when a man appeared and demanded money. The owner opened a cash register. The contents of the cash register were scooped up, and the man sped away. A member of the police force was notified promptly. Statements about the story (True/False/Uncertain) 1. A man appeared after the owner had turned off his store lights. 2. The robber was a man. 3. The man who appeared did not demand money. 4. The man who opened the cash register was the owner. 5. The store owner scooped up the contents of the cash register and ran away. 6. Someone opened a cash register. 7. After the man who demanded the money scooped up the contents of the cash register, he ran away. 8. While the cash register contained money the story does not state how much. 9. The robber demanded money of the owner. 10. The story concerns a series of events in which only three persons are referred to: the owner of the store, a man who demanded money, and a member of the police force. 11. The following events are true: Someone demanded money, a cash register was opened, its contents were scooped up, and a man dashed out of the store.
TaK - Reason • Give examples of some hasty generalisations • Why do you think that people are so quick • to jump to conclusions? • What is the difference between a prejudice, a generalisation and a scientific law?
TaK - Reason • Key points: • It is important to be aware of assumptions, and recognize one is making them, though sometimes it will be necessary to make assumptions (due to urgency of decisions, lacking complete information etc) • Sometimes it is not practical to have all the facts before making decisions; assumptions are necessary, but can be misleading • Assumptions made by individuals (even for the same questions) may be different • Increased awareness and sharing of assumptions can improve decision making
TaK - Reason Informal reasoning – Fallacies (Invalid patterns of reasoning) • Post hoc ergo propter hoc – assume that because B follows A that A must be the cause of B • Ad hominem fallacy – attack or support the person rather than the argument • Circular reasoning – assume the truth of something you are supposed to be proving • Special pleading – making an exception in your own case that you would not find acceptable if it came from someone else • Equivocation – using language ambiguously • Argument ad ignorantium– claim that something is true on the grounds that there is no evidence to disprove it • False analogy – assume that because two things are similar in some ways that they must be similar in some further way • False dilemma – assume that only two alternatives exist when there are in fact a wide range of options • Loaded questions – a question that is biased because it contains a built-in assumption
TaK - Reason • Since strict gun controls were introduced in Dodge City, the crime rate has risen. This shows that gun control does nothing to reduce crime. • Jane said she trusted me, and she must be telling the truth because she wouldn’t lie to someone that she trusted. • The ends justify the means. After all, if you want to make omelettes, you have to break eggs. • Since the English always talk about the weather, if you meet someone who talks about the weather you can be sure they are from England. • Since many great scientists have believed in God, there must be some truth in religion. • We got on very well on both of our dates together. We are clearly well suited. Let’s get married! • Do you want to be part of the solution or part of the problem? • The average UK family has 2.4 children. The Smiths are very average people. Therefore they must have 2.4 children. • Since no-one has been able to prove that we are alone in the universe, we must conclude that other life forms exist. • Are all your family stupid, or is it just you? • No breath of scandal has ever touched the Senator. So he must be an honest man. • Just as you are more likely to take care of a car that you own than one that you rent, so a slave owner is more likely to take care of his slave than an employer is of his worker.
TaK - Reason Bad reasoning • Ignorance • Laziness • Pride • Prejudice
TaK - Reason • Some key points: • Through reason we can acquire knowledge about the world that goes beyond the immediate evidence of our senses • Deductive Reasoning - from the general to the particular • Inductive Reasoning - from the particular to general • Inductive Reasoning sometimes leads to our making hasty generalisations which are then reinforced by our tendency to only notice things which confirm them • Dangers of Informal Reasoning • The main causes of bad reasoning are a combination of ignorance, laziness, pride and prejudice • Logic – the art of reasoning, can all too easily give way to Rhetoric – the art of persuasion
Questions… • What constitutes a 'good reason' for belief? • Does the nature of reason vary across cultures? • Does knowledge always require some kind of rational basis? • If knowledge claims cannot be rationally defended, or can be shown to be irrational, should they be renounced? • How do beliefs affect the capacity to reason logically and the capacity to recognize valid arguments? TaK - Reason