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!