A book that's really changing how I'm thinking. It starts by explaining how science makes progress. Defining a good theory as one that has explanatory power. A good theory explains stuff well.

Then proceeds to apply explanations. How to understand Physics from this frame of mind. How other approaches to epistemology (what we can know) works. What problems they face. What kind of errors other ways of thinking can lead to.

This is the best book I've read about what we can know, and it applies so generally to things I'm interested in. How can I know what I know. What about my team at work, what do we know. How should we communicate. About the products we're developing. How are they valuable? How can we know that it's valuable?

It's especially impressive how Deutsch navigates up and down the ladder of abstraction. Really general concept - then a really crisp example of how it applies exactly to an example.

I've been reading and re-reading this on and off for half a year. It's hard, but I'm learning a lot. Currently half way through the book.