Who once said that warfare was the best way to promote the clear instinct for race selfishness?

The quote about warfare being the best way to promote the clear instinct for race selfishness is attributed to the British philosopher and social Darwinist Herbert Spencer. He believed that conflict and competition were essential for societal progress and the survival of the fittest. Spencer's views reflected the prevailing attitudes of his time regarding evolution, society, and Imperialism. This perspective has been widely criticized for its ethical implications and its role in justifying colonialism and racism.