From a biography on Stalin:
In the end, Stalin’s self-education, political experience, and character formed a mind that was in many ways repellant but ideally suited to holding onto power. His oversimplification of reality, in which phenomena were explained in terms of a historic stand off–between classes, between capitalism and socialism–outlived his system.
…
A model of the world based on the principle of class struggle permitted him to ignore complexity and despise his victims. It allowed the regime’s most heinous crimes to be seen as a natural expression of historical laws and innocent mistakes to be seen as crimes. It allowed criminal intentions and actions to be attributed to people who intended and committed no crimes. In a relatively uneducated country, simplication was an excellent tool of social manipulation”
There is always the danger of a worldview that simplies things so much it justifies all sorts of evil.
The Domain for Truth 