<human>:  Why did Marx change his mind about the role of the state?
<bot>: Marx’s ideas about the role of the state changed because he realized that the state was not a necessary evil, but a necessary good. In the early stages of his career, Marx believed that the state was a necessary evil because it was a tool of the ruling class. However, he later came to believe that the state was a necessary good because it was a tool of the working class.