Karl Popper

A society that is open to change is a society that can progress.

From The Open Society and Its Enemies

The growth of scientific knowledge is based on the critical discussion of existing theories.

From The Logic of Scientific Discovery

We are not infallible, and we must be prepared to learn from our mistakes.

From The Open Society and Its Enemies

The principle of falsifiability is the demarcation criterion of science.

From The Logic of Scientific Discovery

Our knowledge can only be finite, while our ignorance must necessarily be infinite.

From The Logic of Scientific Discovery

Freedom is not a gift; it must be earned and defended.

From The Open Society and Its Enemies

We should be wary of ideologies that promise certainty.

From The Open Society and Its Enemies

Every genuine test of a theory is an attempt to falsify it, or to refute it.

From The Logic of Scientific Discovery

A theory that is not refutable by any conceivable event is non-scientific.

From The Logic of Scientific Discovery

We cannot expect the world to fit our theories.

From The Logic of Scientific Discovery