In his On the Origin of Species, written in 1859, Charles Darwin clearly explained the gradual progression towards the speciation of organisms with his five fundamental principles: variation, inheritance, competition, selection , and propagation. Darwin hesitated to publish his findings because he understood that they were based on the animal kingdom and an evolutionary process that must have spanned millennia. In particular, he did not think that his discoveries were applicable to the evolution of human society. Contrary to Darwin's preferences, Herbert Spencer did exactly what Darwin hoped to avoid by publishing numerous works supporting his new thesis of “social Darwinism,” according to which Darwin's principles of evolution applied directly to the formation of human societies. Although Spencer's application of Darwinian evolutionary ideas was not specifically what Darwin intended, it was an inevitable consequence of the nature of Darwin's discoveries coupled with Spencer's unique upbringing. Although there was legitimate opposition to the theory, Social Darwinism became popular during the late 19th century because it justified growing social inequality in England, the United States, and throughout Europe. Herbert Spencer introduced the seeds of Social Darwinism in 1857 with his second published article on social evolution, Progress: Its Law and Cause. In it, he proposed that “the law of organic progress is the law of all progress” and that this “progress” – from simple to complex – existed throughout the development of all aspects of society: government, production, language, literature, science . , art and more. He then subtly recalled Darwin's five principles of evolution by linking them to the development of a... medium of paper... that existed between societies, not individuals. He also believed that we should not accept social injustices, rather we should work to correct them. Pyotor Kropotkin, a Russian prince, attempted to deny the philosophies of Social Darwinism. In his travels in Siberia, he witnessed mutual aid rather than competition. From his travels he learned that the conflict was not between individuals for survival, but between individuals and nature. In the 19th and 20th centuries, Social Darwinism was a theory that fascinated the world and caused much damage. After being proposed by Spencer, it was hotly debated by contemporary intellectuals and scholars. It eventually became popular because it justified economic inequality and explained why the poor stay poor and the rich stay rich. Social Darwinism was a destructive theory that created pain that continues to be felt today.