As I perhaps did not make very clear: I did not understand the simplicity of the question being asked by the student.
The student merely says that the statement is a circular reasoning (which all statements are if you want them to be..) while I thought that the student didn't understand what fittest means.
Tuppence didn't understand what fittest means according to her defenition of fittest, so perhaps I had it all a bit mixed up...
She still doesn't seem to understand what it means. Perhaps she doesn't have a dictionary or forgot to look the word "fittest" up.
I'll show her (once again) the dictionary defenition of fittest:
Main Entry: 2fit
Function: adjective
Inflected Form(s): fit·ter; fit·test
Etymology: Middle English; akin to Middle English fitten
1 a (1) : adapted to an end or design : suitable by nature or by art (2) : adapted to the environment so as to be capable of surviving
From the Merriam-Webster online dictionary.
So according to the MW fit means adapted to the environment so as to be capable of surviving.
Fittest would then be: best adapted to the environment as to be best capable of surviving.
Since you can replace the word by the defenition you will then get:
Survival of the best adapted to the environment as to best capable of surviving.
Which you can still call a circular reasoning, but if you do so, you can call everything a circular reasoning.