A little gem of a book in the form of two essays from the last few years of Karl Popper's life.
In the first essay, Popper presents a new view of causality, involving the notion of propensities. This is a view that marries Popper's indeterminism with a realist stance that events and processes are properties of the world.
In the second essay, he discusses his evolutionary approach to the problem of knowledge, in which he shows that even the earliest life forms can be interpreted as being based on knowledge, and embodying theories of how the environment behaves and how it can be used. This approach stresses the active nature of life and knowledge-seeking, debunking the idea that knowledge comes in the form of streams of data that the organism passively receives.