René Descartes thought we know objects through reason.

Simple problems may be solved using our senses, but more complicated issues need reason to figure it out. We can easily distinguish between a triangle and a square. But when we consider two polygons, one with a thousand sides and the other with a thousand and one sides, we use reason to tell them apart.

Rationalism characterizes a wide range of philosophical topics.

• How do we know who and what we are? Rationalists claim the self is known through rational intuition, while the empiricist thinks that the unity of the self is illusory.
• What is the natur...