Philosophy addresses questions many of us have previously thought about:
* How do I know that I am not dreaming?
* Is there life after death?
* How do I know that you do not see green where I see blue?
* What is knowledge?
* What is justice?
* What is infinity?
* Is it permissible to lie?
* What is a moral choice?
The search for answers to the above questions (or even the struggle to identify the right question) is at the source of many areas of research: in astronomy, physics, political science, psychology, artificial intelligence, and the cognitive sciences.