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 a SLAVE”
-‘A madman has lost everything BUT his reason’
-‘The HEAD is always fooled by the HEART’
-‘I THINK therefore I AM’
What is REASON? Use of the mind in a logical manner rational - thinking can lead us to important
truths, rules & order - if A=B, and B=C, then A=C
DEDUCTIVE REASONING - moving from the general to the particular
Example:
All dogs are mammals,
Fido is a dog, therefore Fido is a mammal.
We go from ALL dogs to FIDO. These are called SYLLOGISMS
SYLLOGISMS 1) Have two PREMISES and one CONCLUSION
2) Have three terms, each of which occur twice (dogs, mammals, Fido)
3) Have QUANTIFIERS such as ‘all’, or ‘some’ or ‘no’
REASONING:
1) TRUTH vs. VALIDITY 1) STATEMENTS can be true / false
2) ARGUMENTS are valid / invalid
Don’t confuse the two! An argument can be VALID and still not be TRUE!
All flowers are pretty.
Lisa Simpson is pretty.
Therefore Lisa Simpson is a flower. (Argument is valid - but true?)
Pure logic is ONLY concerned with the STRUCTURE of an argument!
Good logic is VALID because the PREMISES and CONCLUSION are logical (but not always
true...). Avoid FALLACIES = failures in logic
Try VENN DIAGRAMS to test AND PROVE your TRUE / VALID argument skills
INDUCTIVE REASONING –
Moving from the particular to the general
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.
DEDUCTION - go from general to specific
INDUCTION - go from specific to general
INDUCTIVE REASONING - Is this the most common reasoning? Is it accurate? Helpful?
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? And 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 Qatari’s I’ve met all shop at fancy stores like Gucci, does that mean they are all
fashion snobs?
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 Qatari’s 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”!
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 - reasoning that SEEMS logical, but is actually LAZY logic
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 - reasoning that SEEMS logical, but is actually LAZY logic
CIRCULAR REASONING = Assuming part of your argument is true BEFORE proving it. Can you
find the unproven part of these arguments?
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 - reasoning that SEEMS logical, but is actually LAZY logic
1) 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 HEART 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 - reasoning that SEEMS logical, but is actually LAZY logic
ARGUING USING AD IGNORANTIAM= Saying something is TRUE just because you can’t prove
is ISN’T TRUE
INFORMAL REASONING - reasoning that SEEMS logical, but is actually LAZY logic
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, AND 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?
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!)
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?
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 - reasoning that actively resists the logic errors
THINK OUTSIDE THE BOX - challenge your ‘habits’ of thinking one way
Term to know:
Deductive reasoning, inductive reasoning
Syllogism, Venn diagram, premise
Validity vs. truth
Fallacy
Informal reasoning (argument 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’
http://mbowe.qataracademy.wikispaces.net/file/view/Tok+Reason+Unit.pdf