Intro to Reason Knowledge Issues: TOK Thoughts about LOGIC & REASON: “You are not THINKING you are just being LOGICAL.” “Logic is the BEGINNING of wisdom, but not the END” “He who cannot REASON is but a SLAVE.” “A madman has lost everything BUT his reason.” “The HEAD is always fooled by the HEART.” “I THINK therefore I AM.”

Intro to Reason What is reason? Use of mind in a logical manner RATIONAL - thinking can lead us to important truths rules & order: if A=B, & B=C, then A=C Three key terms: Deductive reasoning, Inductive reasoning, and Informal reasoning

Deductive Reasoning Moving from the general to the particular EXAMPLE: ALL dogs are MAMMALS, Fido is a dog; therefore he is a MAMMAL. We go from ALL dogs to FIDO. These are SYLLOGISMS

SYLLOGISMS Have TWO premises and ONE conclusion Have three terms, each of which occurs twice Have QUANTIFIERS such as ‘ALL’ ‘SOME’ or ‘NO’

Deductive REASONING TRUTH vs. VALIDITY STATEMENTS can be true/false; ARGUMENTS are valid/invalid Don’t confuse the two! An argument can be VALID and still not be TRUE! All flowers are pretty. Mr. Bush is pretty. Therefore Mr. Bush is a flower. (argument is valid - but not true?) Pure logic is ONLY concerned with the STRUCTURE of an argument!

Deductive REASONING Two true premises and a true conclusion TRY OUT THE DIFFERENCE BETWEEN TRUE AND VALID. CREATE VALID SYLLOGISM WITH THE FOLLOWING PREMISES Two true premises and a true conclusion One true premise, one false premise, and a true conclusion One true premise, one false premise, and a false conclusion Two false premises and a true conclusion Two false premises and a false conclusion

Deductive REASONING Good logic is VALID because the PREMISES and CONCLUSION are logical (but not always true...). Avoid FALLACIES = failures in logic What is the missing premise of these (usually) logical syllogisms 1.Jenny goes to Oxford, so she is smart. 2. Drugs should be legal because they only the harm the user 3. Mr. Jones is a politician, so he is probably lying 4. Cheerleading should be an Olympic sport because cheerleaders have a high level of fitness. 5. John is smart so he can’t play sports

Inductive REASONING INDUCTIVE REASONING - moving from the particular to the general 1) Example: In history, EVERY human I’ve read about has died, I have never heard of a human who has not eventually died, therefore ALL humans will die.

Inductive REASONING DEDUCTION go from general to specific INDUCTION go from specific to general

Inductive REASONING 1) INDUCTIVE REASONING - Is this the most common reasoning? Is it accurate? Helpful? Evaluate the strength of the following inductive logical thoughts: My neighbor’s dog didn’t bite me in the past, so he won’t bite me today either My chair supported my weight in the past, so it will hold me today Local drivers have driven wildly in the past, so I better be careful today USA has supported only Israel in the past, so they won’t be fair to Palestinians this year either. Girls who are smart are often not very sporty, so the smart new girl in our class won’t be good as sports

Inductive REASONING 1) How reliable is INDUCTIVE REASONING? Exceptions - some particular items don’t fit the patterns: If metal A, and B expand when heated, does that mean that ALL metals expand when heated? ( & does water ONLY boil at 100% centigrade?) Novelty - Could you have predicted a platypus from looking at previous birds/mammals? Hasty generalizations - If the Africans I’ve met are tall, does that mean ALL Africans are tall? Prejudice If the Italians I’ve met all shop at fancy stores like Gucci, does that mean they are all fashion snobs?

Inductive REASONING 1) How reliable is INDUCTIVE REASONING? Watch out for CONFIRMATION BIAS: WE TEND TO BELIEVE/REMEMBER ONLY EVIDENCE THAT SUPPORTS OUR BELIEFS, AND IGNORE/ FORGET EVIDENCE THAT GOES AGAINST US. Prejudice is reinforced this way - if you have decided that the English are cold, and Americans are lazy, then you LOOK for evidence to support these comfortable beliefs. Define and give an example for GENERALIZATION, PREJUDICE & SCIENTIFIC LAW. NOW FIND A POSSIBLE EXCEPTION/REFUTATION OF THESE “TRUTHS”!

Inductive REASONING 1) How reliable is INDUCTIVE REASONING GENERALIZATIONS ARE NECESSARY! BUT MAKE THEM AS LOGICAL AS POSSIBLE: NUMBER- research with the largest sample is more accurate VARIETY- within a group look for many different types as possible (such as young people, old, different races, places etc.) EXCEPTIONS - actively think of counter-examples ( guard against confirmation bias) COHERENCE - demand MORE evidence if the claim is surprising/unusual SUBJECT AREA- In some areas generalizations are more reliable than in others (human behavior, for example is harder to predict than animal or chemical behavior)

Informal Reasoning 1) INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic a) Post hoc ergo propter hoc = Mistaking something FOLLOWING something for BEING CAUSED by that something (needs more evidence) The following are true statistics, but could there be another reason for the ‘connection’? AS THE NUMBER OF CHURCHES IN THE USA INCREASES, SO DO THE NUMBER OF PROSTITUTES CRIME IS INCREASING IN GERMANY, BUT SO IS THE NUMER OF COLLEGE GRADUATES. SO EDUCATION IS CORRUPTING THE YOUNG THE HOMELESS MAN WAS SEEN IN FRONT OF THE SHOP BEFORE IT WAS ROBBED, SO HE DID IT

Informal Reasoning 1) INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic b) CIRCULAR REASONING = Assuming part of your argument is true BEFORE proving it Can you find the unproven part of these aguments? THE SOLDIER GAVE OUT THE GUNS, BUT KEPT AN EXTRA ONE FOR HIMSELF. WHEN ASKED WHY, HE SAID “I AM THE LEADER”. WHY ARE YOU THE LEADER? “BECAUSE I HAVE MORE GUNS” I KNOW MY PRESIDENT IS A GOOD MAN, BECAUSE HE SAYS HE IS AND A GOOD MAN WOULD NOT LIE I KNOW I AM SMARTER THAN YOU, BECAUSE IT WOULD BE FOOLISH TO SAY SO IF IT WASN’T TRUE, AND I AM NOT A FOOL.

Informal Reasoning 1) INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic c) EQUIVOCATING= using a word/idea in two different meanings to support your argument FRIES AND A COKE ARE BETTER THAN NOTHING, AND NOTHING IS BETTER THAN GOOD HEALTH, SO FRIES AND COKE ARE BETTER THAN GOOD HEALTH SCIENTISTS SAY THAT RED WINE CAN PREVENT HARD DISEASE. I DRINK A BOTTLE EVERY NIGHT, SO I MUST HAVE A REALLY HEALTHY HEART. CAPITAL PUNISHMENT KILLS GUILTY PEOPLE. UNBORN BABIES ARE INNOCENT; THEREFORE WE SHOULDN’T HAVE ABORTION.

Informal Reasoning 1) INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic d) ARGUING USING AD IGNORANTIAM= Saying something is TRUE just because you can’t prove is ISN’T TRUE

Informal Reasoning 1) INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic 1) ARGUING USING AD IGNORANTIAM= A VERY COMMON LOGICAL ERROR! IF THERE ARE PARTS OF SCIENCE WE CAN’T UNDERSTAND YET, THEN THAT PROVES THERE IS A GOD (because only something smarter than ourselves could have created something we can’t understand) THERE ARE MILLIONS OF THINGS WE CAN BELIEVE IN (FAIRIES, MAGIC, UNICORNS ETC.). JUST BECAUSE WE CAN’T PROVE THEM, DOES THAT MEAN THEY CAN EXIST? CAN YOU THINK OF THEORIES (CONSPIRACY) THEORIES) THAT PEOPLE USE TO DEFEND DIFFICULT TO PROVE/EXPLAIN CONUNDRUMS?

Informal Reasoning 1) INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic e) THE FALSE DILEMMA= BINARY THINKING (- BLACK/WHITE THINKING) TO MY PARENTS: IF YOU DON’T LET ME GO TO THIS PARTY, I’LL BE A TOTAL LOSER AT SCHOOL ARE PEOPLE WHO WANT TO SPEND MONEY ON THE MILITARY AWARE THAT WE’LL HAVE TO CLOSE SCHOOLS AND HOSPITALS? IF YOU ARE AGAINST THE WAR IN IRAQ, THEN YOU MUST HATE AMERICA. IF YOU ARE ARAB AND ANTI-ISRAEL, YOU MUST BE A TERRORIST SYMPATHIZER (WATCH YOUR THINKING! THE WORLD IS MORE SHADES OF GREY THAN BLACK AND WHITE!)

Informal Reasoning 1) INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic f) THE LOADED QUESTION= CONTAINS A BUILT-IN ASSUMPTION DO YOU ALWAYS CHEAT ON EXAMS? THE HEAD TEACHER DID NOT HIT HIS STUDENTS TODAY IF YOU ARE AGAINST THE WAR IN IRAQ, THEN YOU MUST HATE AMERICA. ARE YOU AWARE THAT OBAMA IS A SOCIALIST? CAN YOU PHRASE THE QUESTIONS ABOVE IN A MORE NEUTRAL/UNBIASED WAY?

Lateral Thinking 1) LATERAL THINKING - reasoning that actively resists the logic errors a) The Prison of Consistency - it is harder to change your mind than continue thinking illogical thoughts Professors and parents seldom admit they are wrong. Why? What takes greater courage, to fight for your convictions, or to question your convictions?

Lateral Thinking 1) LATERAL THINKING - reasoning that actively resists the logic errors b) THINK OUTSIDE THE BOX - challenge your ‘habits’ of thinking one way Can you think of a LOGICAL reason for the following situations? A man walks into a bar, asks for a glass of water. The barman pulls a gun on him. The man THANKS him and walks out. A man lies dead in a field by an unopened package. There is no one around. How did he die? A man rode into town on Friday. He stayed three nights and left on Friday. How come? Two boxers are in a match. The fight ends after 6 rounds, after one boxer knocks out the other. But no man throws a punch. How is this possible?

Terms to Know Term to know: Deductive reasoning, inductive reasoning Syllogism venn diagram premise Validity vs. truth Fallacy Informal reasoning arument ad ignorantiam binary thinking circular reasoning equivocation false dilemma loaded questions post hoc ergo propter hoc Belief bias Confirmation bias Hasty generalizations Lateral thinking - thinking ‘outside the box’