It's not circular, it's just true in the purest sense. As all mathematical theorems are either tautologies or consequences of assumptions, therefore pure assumptions.
For me survival of the fittest just means that with high probability those genes will survive who have a high probability to survive in an evolutionary setting. Is this trivial? In this wording it is trivial. But it can be useful. (And also it is not that trivial in a different wording. Just like other theorems, e.g. the theorem about the
perpendicular bisectors of a triangle's sides. If a point O is equal distance from A and B and B and C then it is equal distance from A and C. Tautology, circular, assumption, name it what you want, it's math.)
For me survival of the fittest just means that with high probability those genes will survive who have a high probability to survive in an evolutionary setting. Is this trivial? In this wording it is trivial. But it can be useful. (And also it is not that trivial in a different wording. Just like other theorems, e.g. the theorem about the perpendicular bisectors of a triangle's sides. If a point O is equal distance from A and B and B and C then it is equal distance from A and C. Tautology, circular, assumption, name it what you want, it's math.)