I often wonder when people make such statements if they see the irony in them making such statements.
Then I realise, no they don't.
What's ironic about it? Whether Darwin used the term "survival of the fittest" is (to me) too unimportant to be worth bothering with. Someone trying to lecture others on evolutionary biology without understanding the subject is worth bothering with, however.
No. It's not survival of the most likely. What is 'most likely' to survive is known post facto by seeing which survived
I'm sorry, but this is wrong. Fitness is a statistical characteristic, not a deterministic one. This is trivially true in modern evolutionary biology, in which fitness is characterized by an increased probability of reproduction (usually expressed as 1+s, where s is the selection coefficient). But Darwin also understood this, as is clear from
The Origin of Species. Thus, when introducing natural selection, he writes, "If such [useful variations] do occur, can we doubt (remembering that any more individuals are born than can possibly survive) that individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind?" He describes an increased
chance of surviving; nowhere does he offer the simple tautological formulation you give.
He is more explicit about the issue later in the same chapter, when he writes, "It may be well here to remark that with all beings there must be much fortuitous destruction, which can have little or no influence on the course of natural selection. For instance a vast number of eggs or seeds are annually devoured, and these could be modified through natural selection only if they varied in some manner which protected them from their enemies. Yet any of these eggs or seeds would perhaps, if not destroyed, have yielded individuals better adapted to their conditions of life than any of those which happened to survive. So again a vast number of mature animals and plants, whether or not they be the best adapted to their conditions, must be annually destroyed by accidental causes, which would not be in the least degree mitigated by certain changes of structure or constitution which would in other ways be beneficial to the species. But let the destruction of the adults be ever so heavy, if the number which can exist in any district be no wholly kept down by such causes, -- or again, let the destruction of eggs or seeds be so great that only a hundredth or a thousandth part are developed, -- yet of those which do survive, the best adapted individuals, supposing that there is any variability in a favourable direction, will tend to propagate their kind in larger numbers than the less well adapted." His understanding is precisely that of modern evolutionary biology (although without the mathematical framework): a trait gives greater fitness if those having it are more likely to survive.
The other key fact that makes natural selection an observation about the world, rather than a mere tautology, is that some traits are heritable. The combination of the two facts -- that some traits are more conducive to survival than others, and that some of those advantageous traits can be inherited -- means that species change over time and can adapt to their environments.
I never owned it in the first place, so how could I disown it? I'm just pointing out that you're arguing (incorrectly) about a term that isn't even part of contemporary evolutionary biology.