Survival of the Fittest. It was Herbert Spencer, not Darwin, who coined the phrase 'survival of the fittest' due to the fact that he believed human behavior was designed in a way that strives for self-preservation. Darwin later used the term 'survival of the fittest' in his edition of Origins of the Species. The theory of social Darwinism created the thinking of the 'survival of the fittest' as that the strongest and the fittest should survive and flourish in society, and the weak should be allowed to die out.