Answer:Charles Darwin believed in the theory of NATURAL SELECTION,which can also be called SOCIAL DARWINISM which tries to establish the survival of the fittest within a POPULATION.
Naturalism Theory as stated by Stephen Crane and Jack Johnson they believe that human beings are not rational in taking decisions about their destinies,they believe human beings are blind victims of forces beyond their control,including their own subconscious impulses.
Explanation: The world today is following the Ideas, theories and believes of many scientists like Charles Darwin who stated the law of NATURAL SELECTION where he believes that society through certain conditions shapes itself and determine who and what survives within it.
Stephen Crane and Jack Johnson are also another scientist whose idea is still being felt today most of the activities of man are not rational, examples includes the pollution taking place which is currently the reason for Climate change and Global warning are irrational acts of Humans.