People can get what they want more effectively if they work together cooperatively. The world we live in is organised in a mish-mash of cooperation and competition. This mish-mash is horribly inefficient at providing people with the things they need. Following on from the Prisoners’ Dilemma it should be possible for us all to work together to make things better, but how would that work?
Marx thought he had this all worked out. In his view society was divided into two groups, the capitalists (a small proportion of the population who nevertheless had most of the wealth), and the rest of us, the people who have to work for a living. Marx’s plan was for a small group of working class leaders to form a communist party, which would lead all of the working class in a revolution. All the important stuff owned by the capitalists – property, factories, farms, etc. – would be seized by the revolutionaries. The party would set up a new government in which everyone had to work and everyone received the same amount of wealth. However in Marx’s plan this communist ruling party wouldn’t last long, because in a society where no-one was richer or poorer than everyone else, all forms of oppression and injustice would disappear, the ruling party would fade away, and a workers’ utopia would emerge based on solidarity, equality and justice, fairies and rainbows and magic unicorn farts. So… yeah. In practice it didn’t quite work out this way, as Maoist China, Stalinist Russia, and North Korea all show.
However Marx’s grand plan wasn’t really built on cooperation. Cooperation requires people to talk to each-other. Each person must state their own desires and listen to everyone else’s, and negotiate a solution that everyone is satisfied with. In Marx’s revolution only the members of the communist party truly cooperate; everyone else just follows the leaders. Another way to look at this is that in Marx’s communism wealth is shared out equally, but the power to make decisions is not.