1. How can we deduce the nature of the world?
Reason
How can we deduce the nature of the world?

2. Reason You’re trapped on an Island
A boat arrives each morning, if you know your own eye colour, you can leave
However, a wizard has jumbled up everyone’s eye colour. Now all of your eyes are either brown, blue or green.
He also cursed you, nobody can talk.
There are no mirrors / reflecting surfaces on the entire island

3. Reason
As it happens, there are exactly 100 people with brown eyes and 100 people with blue eyes on the island, and no one with green eyes, but you don’t know that, you only can see 99 people with blue eyes and 100 people with brown eyes.
One day, the wizard turns up and says “I turned at least one person’s eyes blue”
Who leaves, and on what day?
(It might be helpful to think of this as a smaller problem first, for example what would happen if there were only two people, one with brown eyes and the other with blue?)

4. Reason
All the blue-eyed people leave on day 100

5. Reason Think of it like this:
If there were only two people on the Island, and the wizard said ‘I made at least one person’s eyes blue’, then the blue-eyed person would look around and see that he couldn’t see the person with blue eyes. Therefore, he must BE the person with blue eyes, and leave on the first day.
If there were four people on the Island, two with blue and two with brown, and the wizard said ‘I made one person’s eyes blue, both blue eyed people would look around, and see a person with blue eyes, and think “maybe he is the only person with blue eyes”. However, if he didn’t leave on day one, they could work out that HE must have seen someone else with blue eyes, otherwise he’d have left like our first example, therefore there must be someone ELSE with blue eyes, therefore it must be him, and they would leave on the 2nd day.

6. Reason
We use reason all the time, but what is it, and how do we know it works?
Are we as good at reasoning as we think we are?
KLQ: How can we deduce the nature of the world?

7. Reason Here are examples of establishing deductive knowledge:
“All hotels have bathrooms, I am in a hotel, therefore I am in a place with a bathroom”
“All roads lead to Rome, I’m on a road, therefore I am going to Rome.”
KLQ: How can we deduce the nature of the world?

8. Reason
DEDUCTIVE knowledge is when we take a general rule (All Xs are Y, etc.) and apply it to a specific circumstance (This X is Y)
Deductive knowledge is certain, if all the premises are correct you know the conclusion must be true
KLQ: How can we deduce the nature of the world?

9. Reason Write your own examples of deductive arguments.
They should be of the form P1, P2, C.
Remember: start with general premises to come to a specific conclusion
KLQ: How can we deduce the nature of the world?

10. Reason Conversely, we have inductive knowledge
Here are examples of inductive arguments:
“All philosophy students I have ever met have been intelligent. Therefore all philosophy students must be intelligent”
“Swan no 1 is white, Swan no 2 is white, Swan no 3 is white… Swan no 100 is white. Therefore, all swans are white”
KLQ: How can we deduce the nature of the world?

11. Reason
INDUCTIVE statements take repeated instantiations of something specific, and use it to make a general rule.
This is often seen in science, in cases like “Nickel expands when heated, iron expands when heated, tungsten expands when heated … all metals must expand when heated.
This is an uncertain conjecture. It may be the case that you simply haven’t yet seen the example that disproves you.
KLQ: How can we deduce the nature of the world?

12. Reason Come up with two of your own examples for inductive truths
Remember, start with repeated observations of something specific, and use that to make a general rule
KLQ: How can we deduce the nature of the world?

13. Reason How good do you think you are at reasoning?
Would you consider yourself better or worse at it than others? Is it a strength?
KLQ: How can we deduce the nature of the world?

14. Reason
Mary Redgrave is 36 years old, not married, outspoken, opinionated and intelligent. She was raised in Boston, Massachusetts, and completed a degree in sociology and communications at a liberal arts college. Mary was active in student politics whilst an undergraduate, being particularly concerned with issues to do with racism and gender discrimination. She also took part in pro-choice, anti-nuclear, anti-poverty and animal rights initiatives. In the present day, she remains concerned about these things, but has extended her interests to include environmental issues such as renewable energy and climate change.
KLQ: How can we deduce the nature of the world?

15. Reason
What does Mary do for a living? Rank these options from Most Likely to Least Likely:
Mary is an executive for a housing charity 
Mary is a bank clerk 
Mary is an insurance salesperson 
Mary is a bank clerk and remains active in the feminist movement 
KLQ: How can we deduce the nature of the world?

16. Reason How did you rank them?
If you ranked the last option “Mary is a bank clerk and remains active in the feminist movement” as more likely than just “Mary is a bank clerk” you have committed an ERROR IN REASONING
This is because, whatever likelihood you give to Mary being a bank clerk has to also continue to that and her being in the feminist movement. She must have already gotten to this level of probability and added on to it.
KLQ: How can we deduce the nature of the world?

17. Reason This Barber has been sleeping with the King’s daughter
In order to punish him, the King says “you must shave everyone and only everyone that does not shave themselves, if not you will be killed”
Should the barber be relieved?
KLQ: How can we deduce the nature of the world?

18. Reason Think about this: does the barber shave himself?
If he doesn’t, he has to, and if he does, he cannot
There is no way of reasoning out of this. It is a paradox. It’s impossible for the barber not to get killed.
KLQ: How can we deduce the nature of the world?

19. Reason KLQ: How can we deduce the nature of the world?
Do cases like the barber’s show an inherent weakness in reason?
Should we (as Hume argues) be motivated purely by emotion?
What reasons do we have for thinking that reason works?
KLQ: How can we deduce the nature of the world?

20. Reason
“I know it’s 8 o Clock because I have it written down on a piece of paper”
“I know the piece of paper is correct because it says 8 o Clock and it is”
What is wrong with the reasoning here?
KLQ: How can we deduce the nature of the world?

21. Reason
KLQ: How can we deduce the nature of the world?