The Beginning of Infinity by David Deutsch
He discusses different types of infinities, the many worlds interpretation of quantum theory, group decision making and constraints to political representation, memes and genes, the importance of technology and many, many more ideas.
The book also provides a highly unnecessary dialogue modeled on Plato and a brief, but decent, dismissal of Diamond's environmentalist approach to understanding the world.
Deutsch reaffirmed my belief in the importance of science and technology as it is only recently that if an asteroid were going to hit Earth we might be able to deflect it (instead of just watching it hit us or hiding in caves/bunkers). It makes sense to develop our science and technology to address potential catastrophes like climate change or flu pandemics, and even more sense given that there may be problems we cannot anticipate.
While I don't agree with all his theses, I would recommend this book for those who want to think a bit deeper about how they come to know things and how good explanations impact the world.
ps: I did like his suggestion of renaming 'hypothesis' with 'misconception.' As in, "Einstein's misconception of gravity has fewer errors than Newton's misconception of gravity."