"Survival of the Fittest" was not Darwin's idea. The phrase was coined by Spencer, who misinterpreted Darwin's work. It has since been used primarily to either

"Survival of the Fittest" was not Darwin's idea. The phrase was coined by Spencer, who misinterpreted Darwin's work. It has since been used primarily to either further misunderstanding or to apply Darwinism to realms like society and race, generally to distasteful or even horrific result. It's a reliable marker for writing that will irritate people who've actually studied evolutionary biology.