The Intuition and Deduction Thesis

Intuition

The immediate understanding of a truth by the mind which does not involve reasoning or inference.

Deduction

The use of step-by-step reasoning from known truths to lead to another truth. It often uses syllogisms.

Syllogism

A type of reasoning where you start with two ideas that are true and use them to make a new, true conclusion.

Clear ideas

Ideas that are easy to understand and accessible to the mind.

Distinct ideas       

Ideas that are separate from all other ideas.

Cogito ergo sum  

I think, therefore I am

a priori knowledge  

Knowledge gained without any sense experience. You don't need to go and find anything out from the world. 

Trademark Argument

Descartes’ argument that the idea of a perfect God must be caused by a perfect being, therefore God exists.

Cause principle (Trademark Argument)

The cause of something must contain at least as much reality or perfection as its effect.

Role of God in Descartes’ epistemology

God guarantees that clear and distinct ideas are reliable and not deceptive.

Descartes’ proof of the external world

Because God is perfect and not a deceiver, our strong sensory beliefs about the external world must be true.

David Hume’s objection to the cogito

We never experience a stable self, only changing perceptions and thoughts. The self is just a bundle of changing perceptions rather than a single stable substance.

No thinker problem

The cogito may only prove that thinking occurs, not that a thinker exists.

Response to the no thinker problem

Thinking necessarily implies a thinker, so the existence of the thinker is revealed in the act of thinking.

Hume’s Fork

The division of knowledge into relations of ideas and matters of fact.

Relations of ideas

Analytic, a priori propositions that are necessarily true (e.g. logic or mathematics).

Matters of fact

Synthetic, a posteriori propositions that are contingently true and known through experience.

Response to Hume’s Fork

Rationalists argue that reason can provide genuine metaphysical knowledge, such as knowledge of God.

Cartesian Circle

The criticism that Descartes relies on clear and distinct ideas to prove God but uses God to guarantee the reliability of clear and distinct ideas.

Response to the Cartesian Circl

Clear and distinct ideas are self-evidently certain when perceived, and God later guarantees their general reliability.