Karl Popper's dictum holds true for the scientific thought. You make a prediction about your theory and then every one tests to see if its true. Then they look at other claims and put them through similar tests. After empirical verification, if all the predictions hold up, the theory becomes an accepted part of science. Charles Darwin is still hugely consequential because no one has been able to refute his simple and at the same time elegant explanation of how natural processes operate. This doesn't exclude a Proximate Cause; its just that Occam's Razor holds the correct explanation is the one that get things right with the fewest explanations possible. That's why evolutionary theory has such a central place in biology and in understanding the history of life on the planet.
(Denny Crane: "I Don't Want To Socialize With A Pinko Liberal Democrat Commie.Say What You Like About Republicans. We Stick To Our Convictions. Even When We Know We're Dead Wrong.")