And on reflection, although scientists have come to reject many past theories, it remains true that those theories were often highly effective within the contexts that they had been developed and tested. The old earth-centered model of the solar system was supremely accurate for predicting the locations of stars and planets. We still use Newton’s law of gravity to calculate satellite trajectories—and Newton’s theory sufficed to get us to the moon. In other words, we make our beliefs as good as we can on the basis of the evidence we have, and, often enough, things work out.
