In The Big Questions, Steven E. Landsburg uses math, economics and physics to discuss questions of philosophy, especially morality and ethics.
That sounds a lot more serious than the book turned out to be. In fact, Landsburg ends the book by saying that most of it was written "not to make any particular point but because it seemed to fit and I think it’s interesting."
It’s a good introduction to some basic econ, math and physics, and to Landsburg’s own beliefs and guidelines on life (including the reasoning behind them). Many of the examples and anecdotes were old news to me, because I have already taken courses in math, physics, economics and philosophy. But it’s well-written, entertaining and easy to read.
* If more people really and truly believed in the religions they claim to follow, they would behave differently. For example, why don’t we have more suicide bombers? Landsburg concludes that hardly anyone is actually religious:
"If religious belief were as widespread as people claim it is, there should be millions upon millions of voluntary martyrs. (…) Believers in hell should commit fewer crimes; believers in heaven should take more risks; believers in one religion should interact in predictable ways with believers in another; believers in God should have a powerful interest in the alternatives. Those implications are testable. I am moderately confident that carefully gathered statistics would refute the hypothesis that religious beliefs are widely or deeply held."
* If you want to write, study something you love and write about it. Do not take writing classes:
"If your writing is murky, it’s usually because your thinking is murky, too. The cure for that is not a series of writing exercises; it’s to master your subject matter. (…) Prose flows easily when you understand what you’re saying. If you’re struggling to ‘craft’ your prose, you’re probably confused."
* The Economist’s Golden Rule: Don’t leave the world worse off than you found it OR Don’t spend valuable time and energy in non-productive ways. It follows that you should not steal, counterfeit or be an Olympic athlete:
"If you bake a cupcake, the world has one more cupcake. (…) But if you win an Olympic gold medal, the world will not have one more Olympic gold medalist. It will just have you instead of someone else."
(Cupcake by Kuidaore)