Philosphy and War: Ideas Worth Dying For:

Ideas like humanism and Social Darwinism came to a head in Europe, leading to World War One. Then Nietzsche's existentialism led to fascism in Germany, Italy and Japan while Marx's Marxism led to real communism in Russia. These ideas clashed, leading to World War Two. It continued through the 50-year cold war as well. Above all else, these wars proved that ideas aren't just ideas; they have real consequences.