Communism
One of the best known philosophical systems that created a new type of government in a large number of countries and profoundly influenced the politics and the daily life of the rest of the world, started and stopped wars, accelerated and halted sciences and technologies, and essentially directed the course of the entire human history for the most of the 20th century is communism. Communism had always existed – in tribal societies and in religious communities where members had no private properly or monetary reward for labor, worked as much as they could, and received goods according to their needs, but only Karl Marx in the 1850s saw how this concept fits in his philosophy of class struggle as the perfect society of the future. Not only did he describe the utopian world where no division of labor exists (“hunt in the morning, fish in the afternoon, rear cattle in the evening, criticise after dinner”), and no currency, and no property, and not even state, but he also wrote a detailed plan for reaching that ultimate goal, beginning with socialism and dictatorship of the proletariat, where the entire class of workers gains communal ownership of the means of production, taking it by force from the current owners.
During his lifetime, only the Paris Commune in 1871 established the dictature of the proletariat for a few months, but in 1917 the proletariat in Russia seized power, toppling the weak provisional government created after the recent dissoluton of monarchy, launching what later became one of the world’s superpowers, the Soviet Union. Despite extensive planning by Lenin and other theorists, the dictature of the proletariat became the dictature of a single party and a single person, in an odd parallel to the contemporary rival political system of fascism in Europe. Communism spread to take over China and a large number of smaller countries, following its official doctrine of unstoppable world revolution, turning each of those countries into either a dictature of its own or into a puppet state. The capitalist world mobilized itself to counteract this spread, the opposition bringing and keeping the entire Earth at the brink of an all out war for several decades. Communist governments eventually fell in the majority of these countries, having never reached the ultimate goal of classless society.
Many things can be said about the viability of the Marxist utopia, of the reasons it did not perform as envisioned when put to the task, but the fact is, this is a philosophical system which affected the lives of billions of people, it is the most influential philosophical system to ever exist.