propositions mathematics and logic are obviously closely related
TRANSCRIPT
Propositions
Mathematics and logic are obviously closely
related
Proposition……..any statement that can be asserted or denied (i.e. said to be true
or false)
Examples of propositions
Snow is white
Examples of propositions
Liquid nitrogen is very cold.
Examples of propositions
Pigs have wings
Examples of propositions
Polish men are very sensitive and understanding
IB students are not very enthusiastic
Examples of propositions
4 kinds of propositions
1. Analytic propositions (2 types)
Propositions that can be shown to be true just by analyzing (thinking about) them.
1. Analytic propositions - 2 types
Definitional truths;
All bachelors
are unmarried men
1. Analytic propositions – 2 types
Truths of reason; If Eerik is taller than Rami, and Rami is taller than Bartosz, Eerik must be taller than Bartosz
2. Empirical Propositions
Their truth can be determined by appeal to evidence based on perception
2. Empirical Propositions
Pandas eat bamboo
2. Empirical Propositions
Smoking can damage your health
2. Empirical Propositions
Hitler was a woman
3. Value judgments
A statement that contains a value word such as “good”, “bad”, “right”, “wrong”, “beautiful”, “ugly”……..
3. Value judgments
Harder to establish the truth as two people may have different values
3. Value judgments
Kirsten Dunst is beautiful
3. Value judgments
Mr Porter is the World’s best TOK teacher
3. Value judgments
Rap isn’t good music
4. Metaphysical propositions
Neither analytic, empirical nor value judgment. This leaves statements about the nature of ultimate reality
4. Metaphysical propositions
God exists
4. Metaphysical propositions
Free will is an illusion
4. Metaphysical propositions
The past does not exist
Importance of knowing which type of proposition
Because all 4 types can be justified in different ways, it is important to know which type of proposition we are dealing with when looking at a knowledge claim
State whether the following propositions are analytic,
empirical, value judgment or metaphysical
God is the creator of all things
Mozart was a great composer
Bananas are yellow
Smith is a courageous man
Napoleon was defeated at Waterloo in 1815
YouTube - Duel and duelality part2
You ought to eat more cabbage
Every event has a cause
A straight line is the shortest distance between two points
Vedran said that a telescope has two lenses
All mass murders are insane
It’s not that simple!
In “real life” there are grey areas and complications
Factual/verbal disputes
Analytical/empirical propositions
What looks like a factual dispute can sometimes become a verbal dispute about the meaning of words
John is bald
Abortion is murder
Nelson Mandela is a terrorist
Nominal Fallacy
Assuming we have explained something just because we have named it
Nominal Fallacy
“Why is iron attracted to a magnet?”
“Because iron is magnetic”
Nominal Fallacy
“Why are there many tribal wars in Papua New Guinea?”
“The people there are very aggressive”
Nominal Fallacy
“Why is lead heavy”
“Because it is very dense”
Nominal fallacy
Try to spot the nominal fallacies in the following;
Nominal Fallacy?
“What caused the baby’s death”
“Sudden Infant Death Syndrome”
Nominal Fallacy?
“Why did the water pipes burst?”
“Because the temperature fell below zero(freezing), and when water freezes it expands”
Nominal Fallacy?
“What caused the earthquake”
“A sudden movement of rocks beneath the earth’s surface”
Nominal Fallacy?
“What caused the earthquake?”
“It was an act of God”
Nominal Fallacy?
“Why does sugar dissolve in water?”
“Because it is soluble”
Nominal Fallacy?
“Why did the apple fall to the ground?”
“Because of gravity”
Nominal Fallacy?
“Why did the apple fall to the ground?”
“Because of gravity”
Nominal Fallacy?
“Why did Peter Sutcliffe murder 13 people”
“Because he is insane”
Nominal Fallacy?
“Why did the stock market fall yesterday?”
“Because of a technical adjustment and profit-taking by investors”
Nominal Fallacy?
“Why did he win the lottery?”
“Because he is a lucky person”
Empirical propositions and value judgements
Empirical propositions and value judgements
Many words have positive and negative connotations that can blur the distinction between a fact and a value
Connotations
Blair is a murderer
Connotations
Cristina is a spinster
Connotations
Albert is brainy
Connotations
Can you think of some propositions of your own in which an empirical proposition is turned into a value judgement by a connotation?
Relevant facts
Some empirical facts may be relevant to the justification of value judgements
Relevant facts
Gary is a bad man
Relevant facts
Tiger is a good golfer
Relevant facts
The British School is a good school
Empirical propositions and metaphysics
Empirical propositions and metaphysics
Some empirical facts may be relevant to the justification of our metaphysical beliefs
Empirical propositions and metaphysics
God created the universe in six days about 6000 years ago.
Push hard enough!
If you push an empirical proposition hard enough, it collapses into a metaphysical one.
Empirical proposition
Push hard enough!
If you push an empirical proposition hard enough, it collapses into a metaphysical one.
Metaphysical proposition
Push hard enough!I know that my car is parked outside
But how can you be sure you are not
dreaming?
Push hard enough!I know that all
metals expand when heated.
But how can you be sure the laws
of physics will hold tomorrow
?
Push hard enough!
I know that World War 2 started in
1939
But how can you be
sure the past really
exists?
Fortunately we have seen that you
don’t need complete certainty to say you “know”
something!