I understood “Darwinism” to not exist (according to all the best representatives of Science). Do you, perchance, have in mind the Darwinian Theory of Evolution and its logical corollary, the theory of the survival of the fittest)?
But, using your expression “Darwinism” for the moment, permit me to observe that “Darwinism” possesses no personality and lacks the ability to define anything. It is those who use the term who define the “unfit.” Defining “the unfit” is a favorite pastime of Darwinian mullahs and imans, so does your horizon expand to include religious and political Darwinism, in which case we would have to declare the Aztecs and the ancient Egyptians “unfit,” or does it have no connotations other than scientific, and can therefore lead us to no religious or political conclusions?
The term “Darwinism” is used by supporters of the theory of biological evolution and as used here is obviously the intended meaning.
Yes, it, Darwinism, can define just as it can be said “the law defines legal and illegal,” or some act as falling under proscription.
Of course anyone can grab the phrase, “survival of the fittest” and apply to whatever they wish with the same desire to appear to appeal to an immutable force that is functioning in the background.
But as in the case of biological Darwinism it is no more than saying, “If you're so smart, howscum you ain't rich?”.
It is both self justification and self definition. What doesn't survive wasn't “fit” to survive.