Karl Popper — Austrian Philosopher born on July 28, 1902, died on September 17, 1994

Sir Karl Raimund Popper CH FBA FRS was an Austrian-British philosopher and professor. He is generally regarded as one of the greatest philosophers of science of the 20th century... (wikipedia)

We have become makers of our fate when we have ceased to pose as its prophets.
Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.
No rational argument will have a rational effect on a man who does not want to adopt a rational attitude.
In so far as a scientific statement speaks about reality, it must be falsifiable; and in so far as it is not falsifiable, it does not speak about reality.
Good tests kill flawed theories; we remain alive to guess again.