Reason and Experience: certainty

Decartes:

• Understood knowledge in terms of what is `completely certain`.

What is certainty?

• Subjective & psycholgical meaning.
• Logical meaning.
• That a proposition cannot be doubted.

.

Contigent/ necessary:

• A proposition is contingent if it could be true or false.
•  e.g there are more types of insect than there are animals. But this wasnt always true and oe day it might be false again.
• Aposteriori knowledge is contingent.

• A proposition is necessary if it is not only true- but must be true.
• e.g mathematives are usually thought to be necessary- 2 +2 must equal 4.
• Analytic truths are necessary.

Introspection and tautology:

• A tautology is a statement that says the same thing twice in different words.
• what is tautological is certain.

Can any beliefs other than beliefs about analytic truths be