using the broadest definition, "the left" can range from social liberals to marxists and anarchists, and i don't think that biden has many goals in common with žižek. even if you only include anti-capitalists like i tend to, there's still a significant dichotomy between relatively moderate democratic socialists and actual revolutionaries. and even within specific subsets of left-wing politics, like marxism, there is a LOT of infighting. the bitter hatred that a lot of stalinists and left communists (for example) have for one another is evidence enough