What are the basic question posed by racism, xenophobia, sexism and homophobia, by all these social behaviours which reveal human alienation and which can go as far as murder. How does one explain such an unleashing of social violence; how do you understand these prejudices which seem to come from a bygone age of superstition? How, faced with these types of problems, do you guard against the ideological thinking that the bourgeois system abundantly spreads around in order to mask reality and accentuate the divisions which weaken its historic enemy, the class of proletarians?