Let me point out a few examples. Those that survive are the fittest, and they are fittest because they survived. It is a remarkably universal tautology. So all of the species now extant are, according to Darwin, fittest. Several of us think that science was, is, and will continue to be an activity of the mind rather than a spiritual quest.
Science is largely a search for precedent.
If this, we observe that. By applying mathematics and logic we deduce rules that are useful in understanding the physical world. Some of the precedents are quite compelling, and we call them physical laws, as in Newton's laws of motion. Let's engage in a little speculation on the precedent that evolution provides. Plants and animals as individuals live and then die.