We should take care not to make the intellect our god;

it has, of course, powerful muscles, but no personality.

It cannot lead; it can only serve.

- Albert Einstein

Rationalism

Deductive logic & inductive logic

A. My first confession was a murdererB. Father I was your first ever confession

ThusC. They have a murderer sitting at the

table

Example:A priest is at a party

If A & B are true, then C must also be true.

The advantage of approach is that you can create new knowledge just with the

power of your own mind.

You don’t need evidence.

Rationalist approach

that we can ascertain truth by the process of thinking

and reflection alone.

IS THIS TRUE? DO YOU AGREE?

Deductive LogicGiven the truth of some information, then the conclusion must also be true.

A. All humans are mortalB. I am human

thusC. I am mortal

Leads from general to specific

Inductive LogicLeads from several specific observations to a general conclusion

Example: All swans are white.

Example: There are heavy grey clouds in the sky, it will rain today

‘the problem of induction’

This is incredibly imprecise way of thinking, but also the most common.

Why are we willing to accept it?

Lucky streaks

Why do people believe? •Because it works for us most of the time•Because we want to see patterns in life.

Because it’s how we learned about the world.

It’s very troubling – because it’s a very poor way to ascertain truthThus

We must learn how to use it better

Problems with deductive logic

ProblemLogic is not always easy to see.

A. No monkeys are soldiersB. All monkeys are smellyC. Some smelly creatures aren’t soldiers

Problem

Which is true?

For a deduction to be correct: - the premises must be true - and the logic must be true

ProblemPeople tend to naturally embellish, make assumptions, & jump to conclusions.

ProblemDefinitions, e.g. Art

Define ‘bachalor’

Anthonyis seventeen. He attends school & lives with his parents.

Charles & Chrisare a gay couple who have lived together for 20 years. They cannot be married by law.

Edwardis married to a woman who paid him $25,000 to get married so she could get citizenship. They will divorce as soon as she has citizenship. They live together but he dates other woman.

Father Francisis a catholic priest.

If we can’t agree on terms then our argument is about definitions, not about logic.

This is a very common mistake.

e.g. does explicit violence on TV effect children’s behaviour?

ExampleA man walks into a bar, and asks the bartender for a drink of water. The bartender pulls out a gun, points it at the man. The man says "Thank you" and leaves. Why?

Logic & Lateral thinkingLogical thinking constructs a chain of reasoning. ExampleA man goes to a party and drinks some punch. Then he leaves the party. After he leaves, everyone at the party dies of poisoning. He does not die. Why?

The answer is logical, but difficult to see.

"Logic is the tool that is used to dig holes deeper and bigger, to make them altogether better holes. But if the hole is in the wrong place, then no amount of improvement is

going to put it in the right place. . . . Vertical thinking is digging the same hole deeper; lateral thinking is trying again elsewhere."

- Edward de Bono

Lateral thinking is solving problems through an indirect and creative approach, using

reasoning that is not immediately obvious and involving ideas that may not be obtainable by using only traditional step-by-step logic. The

term lateral thinking was coined by Edward de Bono in the book New Think: The Use of Lateral Thinking published in 1967.

- Wikipedia

If you want to make someone hate you, explain to them,

logically and politely, why they are wrong.

- J. Blaylock

H/WFind an actual fallacy in the news media

http://www.emagill.com/rants/eblog114a.html