Does all knowledge about what exists rest on sense experience?

• We can have knowledge of two sorts of things: 'Relations between ideas', and 'matters of fact' 
• Relations of ideas are propositions like 'all fathers have sons'
• Hume argues that all a priori knowledge (statements which are true by definition, outside of experience) must be analytic, and all knowldge of synthetic propositions must be a posteriori (statements which are not implicit in the definition of the subject but must be known through experience)
• Anything that is not true by definition ('matters of fact') must be learnt through the senses 
• Hume's 'matters of fact' are analytic

• Hume says that the foundation of knowledge of matters of fact is what we experience here and now, or what we can remember 
• All our knowledge that goes beyond the aforementioned rests on casual inference
  • For example, if I receive a letter from a friend with a French postcard in it, I'll believe my friend is in France.
    • I know this because I infer from post mark to place
    • I think that where something is posted causes it to have a postmark from that place.
    • If that letter was posted by my friend, I would believe they were in France.
• I 'know' this because I rely on past experiences
• I don’t work out what causes what by thinking about it 
• It is only our experience of effects and causes that brings us to infer what cause has what effect 
• Hume denies that this is proof 
• He says that knowledge of matters of facts, beyond what we're experience here and now relies on induction and reasoning about probability 

The terms relate to a type of argument

• An inductive argument is where the conclusion is not logically entailed by its premises, but supported by them
• If the premise is true the conclusion is likely to be true
• The french letter is an example of inductive reasoning

• A deductive argument is an argument whose conclsion is llogically entailed by its premises 
• If the premises are true, the conclusion cannot be false. 
  •  
    • E.g. Premise 1: Socrates is a man
    • Premise 2: all men are mortal;
    • Conclusion: Socrates is mortal

Rationalists argue against Hume saying that some claims about what exists can be grounded on a prior intuition.

A priori demonstration, or deduction, is deduction that uses a priori premises

Rational intuition is the view that you can discover the truth of a claim by thinking about it