he achieved the idea of darwinism

Darwinism is "agreeing with the ideas of Charles Darwin about evolution".

That is the correct spelling of the proper noun Darwinism. It refers to the theories of biologist Charles Darwin, specifically the survival of the fittest.

Cons???

Darwin was an honest scientist so I have no idea what you are talking about.

Charles Darwin did not advocate for Social Darwinism. The concept of Social Darwinism emerged as an interpretation of Darwin's theory of natural selection, but his own work focused on biological evolution and the adaptation of species to their environment, not on applying his ideas to human society.