1. Rationalism

2. Rationalism Plato Thinks only Forms are suitable objects of knowledge
Forms tell us what is eternally and necessarily true
Forms can be known purely intellectually

3. Rationalism Plato Is the great early hero of Rationalism
Pure Reason is the route to knowledge

4. Rationalism
Heroes of Rationalism
Descartes
Spinoza
Leibniz

5. Knowledge A Priori Definition:
Something is known a priori when it is a true belief whose justification does not depend on evidence from sense experience.
Something is known a posteriori when its justification does depend upon sense experience

6. Knowledge A Priori Examples 5 + 7 = 12 I think, I am
Nothing can be a both a circle and a square
All bodies are extended

7. Knowledge A Priori Compare There are 12 eggs in this carton You exist
This is a circle
This is a body

8. Knowledge A Priori ‘Characteristics’
Everyone (who is mentally competent) will agree they are true
No possible experience could lead us to doubt them
Not just truths about our ideas of things, but of the things themselves
Leibnitz: Truths of Reason
Not justified by logic, since logic is itself known a priori

9. Knowledge A Priori Curiosities How can we know anything a priori?
Known in the light of Reason. But what Reason?
Just the ‘correct’ working of the Mind?
By an intuition?
How would an intuition count as knowledge?
We can be fallibilists about a priori knowledge
We know a priori that = 12
But we can be wrong about

10. Analytic Statements Definition:
A statement is analytic when its truth may be known simply by knowing the meaning of the constituent terms
A statement is synthetic otherwise

11. Analytic Statements Examples All bachelors are unmarried
All bodies are extended
If Cain killed Abel, then Abel is dead.
If Al is heavier than Bob, and Bob is heavier than Chuck, then Al is heavier than Chuck
5 + 7 = 12

12. Analytic Statements
Compare
Cain killed Abel
I am a bachelor

13. Analytic Statements Connection to A Priori The old view
If something was known a priori then it was because it was expressed in an analytic statement
If something was expressed in a synthetic statement it could only be a posteriori knowledge
So all knowledge was either
Analytic a priori or
Synthetic a posteriori

14. Analytic Statements Connection to A Priori Hume’s problem
Statements of cause were thought to be analytic
But the idea of a necessary connection between the cause and effect couldn’t be got from the meanings of the terms
So they can’t – by the old view – be a priori either
But no number of observations of events will ever observe a necessity
So we can’t have synthetic a posteriori knowledge of causes either

15. Analytic Statements Connection to A Priori Kant’s solution
Note that even = 12 isn’t really analytic
The concept of ‘12’ is not contained in the concepts of ‘5’, ‘+’, ‘7’, or ‘=’ taken together or separately
But it is known independently of all experience, so a priori
Thus there is a category of synthetic a priori knowledge!

16. Analytic Statements Analytic Synthetic a priori a posteriori
Analytic
Synthetic
a priori
All bachelors are unmarried
All bodies are extended
What will be will be
Either Socrates is mortal or Socrates is not mortal
5 + 7 = 12
Nothing can be a both a circle and a square.
If all men are mortal, and Socrates is a man, then Socrates is mortal
a posteriori
Cain killed Abel
I am a bachelor
Socrates is mortal
There are 5 eggs here and also another 7 eggs here
Analytic Statements

17. Analytic Statements Connection to A Priori Kant’s solution
How is synthetic a priori knowledge possible?
Our minds impose a certain structure upon our experience
Space, time, causality are ways we organize our sensations

18. Innate Ideas Definition:
An idea is innate if it does not derive from our experience of the world
An idea is acquired otherwise
An idea may be either a belief or a concept

19. Innate Ideas Innate beliefs Innate concepts 5 + 7 = 12
If all men are mortal, and Socrates is a man, then Socrates is mortal
Nothing can be a both a circle and a square
Innate concepts
God
Causation
Space and Time

20. Innate Ideas Why imagine there are innate ideas?
Some ideas are beyond the capacity of experience to justify, or even to produce
5 + 7 = 12 could not be discovered to be necessarily true by any number of experiences of the kind: ‘I got 5 eggs and then 7 more eggs, and now I have 12 eggs.’
We might try an induction, but why would we think induction is that reliable? It couldn’t give us necessity in any case.

21. Innate Ideas
Note
An idea being innate says nothing about its justification
The relation between innate and a priori is not straightforward.

22. Rationalism Criteria for Rationalism
More of a family of positions really.
Tend to accept:
1. We have privileged modes of cognition
2. We have a priori knowledge
3. We have innate ideas

23. Rationalism 1. Privileged modes of cognition
Yield a priori knowledge – independent of senses
Deduction is one
Logically deduced truths are indubitable
We may have special intuitions
Plato’s apperception of Forms
Our own acquaintance with truths of logic, meaning, maths, etc.

24. Rationalism 2. We have a priori knowledge
Plato thinks that’s because we have a special perception
Others think it’s because of a special intuition
Most think that nothing special is required more than a simple understanding of the nature of the concepts involved
NB. It can’t be just by deduction because that’s how the knowledge of deduction is given to us

25. Rationalism 3. We have innate concepts
Plato thinks that’s because we’ve been in contact with the Forms before our birth
Kant thinks it’s because our minds are so constructed