I first read Plato's 'Republic' back in 2002 after being prompted by this wonderful person called Yasmin. Two things struck me about the book, the first was the Socratic dialogues at the beginning which blow the mind, the way he makes you question the basis upon which we rest our most deeply held beliefs is incredible and you can appreciate why someone who asked such penetrating questions would make enemies. The other is the question of communism.
I shall start, as I often do, by examining the etymology. The word 'communism' first appeared in the middle of the 19th Century in France in the form communisme and that probably came from the Old French word commun (meaning common) and from the Latin before it with communis. I think I'm right in saying that there is no equivalent word in Ancient Greek so if Plato did invent the concept of communism, he certainly did not create the word. Since we are talking about a utopian belief, that is a word which is also worth considering, especially since Sir Thomas More's treatise 'Utopia' is also touted as a possible birth of communism. Thomas More's usage of the word utopia seems to be the first in English and it comes from Late Latin and from the Greek words before it, ou + topos, literally meaning 'no place' which seems rather apt given the subject.
So, word histories aside, you might be wondering what is it that makes me draw the comparison. In the 'Republic', Plato argued for a Commonwealth, a society in which the community would take responsibility over many of the social aspects of life, from the provision of education and healthcare to the ownership and distribution of property. Almost everything was to be held in communal ownership, including children (who were to be taken away from their parents and cared for and educated by guardians) and women (although I'm not too sure I understand the specifics about the communal ownership of women so it's probably best to gloss over that aspect of his philosophy).
There are, however, some caveats to examine. Plato's utopia of community ownership did not apply to everyone in his society, but was reserved to his 'guardian class'. There is another, almost sinister (now, the word sinister has a fascinating history but I shall write about that some other time as I can see eyes begin to droop) aspect to Plato's philosophy. It is clear from his words that his political philosophy was not one that he believed the masses would necessarily choose, and that didn't particularly bother him. Plato believed in the idea of a elite ruling class. He envisioned philosopher-kings who would be enlightened rulers and act in the interests of his people, even if they did not agree that their actions would be in their interests. In other words, Plato's social system would be enforced on its populous and his guardians would be the police force which has to be the precursor to despotism and authoritarian rule.
I don't know enough about early Ancient Greek scholars to argue conclusively that Plato did invent the concept of communism, but it is certainly true to say that some of the ideas that exist in his 'Republic' have helped form that school of political philosophy. Plato seems to be a great example of someone who has exhibited such an extreme belief that he is neither communist nor fascist, but displays elements of both and it is true; when you go so far off one end of the spectrum, you end up on the opposite side.