I'm passionately interested in Darwin and evolution, but have been bashing my head against the wall recently, over the objection that 'survival of the fittest' is a tautology. The answers to this that I've read state that 'fitness' doesn't mean:
"those that survive, but those that could be expected to survive because of their adaptations and functional efficiency"
But then the reply to this seems to be:
"This charge is not repelled by substituting "most adaptable" or "best designed," etc., for "fittest," because these too are determined by survival. (That is, how do we determine that a species, or members of a species, is "most adaptable" or "best designed"? By the fact that it survived.)"
As an aside following on from this, I know that you can then say that there is a lot of evidence. But isn't this evidence for evolution, not the specific theory of natural selection?
My question is: is there a logical rebuttal to the statement that it is a tautology, and therefore apparently 'devoid of explanatory power'? I'm actually rather worried about this, having based much of how I view the world on natural selection.
Thanks, and sorry if the answer is very obvious to you!