A political philosophy first expounded by Karl Marx which states, roughly speaking, that money corrupts and everyone should share equally in the rewards of society. It has largely been championed by academics and radicals who, it should be pointed out, are not known for working particularly hard or making a lot of money in the first place. Not surprisingly, among the general public Communism has proven much more popular among the poor than the rich.
In practice, there has been a regrettable tendency for countries which have become Communist to also become dictatorships, which leaves some questions as to whether its problems are inherent to the theory or just to the way it is currently realized. Its basic flaw, however, can be summed up as a variant of the "above-average perception problem": 90% of drivers believe their driving skills are above average. Similarly, most workers honestly believe they work harder and are more valuable than the guy sitting next to them. This works fairly well when one is directly competing for raises and bonuses, but once everyone's guaranteed the same paycheck you're just as likely to pack it in at midday to hit the beach.