While I understand the generalized and simplified exercise you are engaging in, simplifying and generalizing at the same time can make it even more difficult, if not impossible, to reach a meaningful understanding. There is actually a lot of gray space between the black and white extremes. Capitalism is an economic system based on private ownership of the means of production and their profit (which is distributed to the owners) and can be compared to feudalism or colonialism, but I wouldn’t compare it to communism or socialism, or democracy for that matter. Democracy is a form of government where the people choose their governing authorities. Communism and socialism are philosophical ideas. You can compare democratic extremes though, such as laissez faire capitalistic democratic systems versus socialistic democratic systems. The Scandinavian countries are excellent examples of the second, while pre-antitrust America (and arguably 21st century America as well) is a good example of the first. The Scandinavian example illustrates a very successful ‘blending’ of communism and laissez faire capitalism where a ‘happy medium’ is found: simplifying (again, very dangerous) the private is kept private whereas the public is a shared entity. Socialized medicine is a great example: health and medicine are arguably public goods, not private, but even in that sector there is a mix of private and public practices, and professionals who participate in both. The command economy (and I will end with this) can be either fascist, where control is centralized but the profits are privatized, or communist, where control is also centralized but the profits (if and when they exist) are public and distributed with no rational criteria relating to input.

I disagree with your conclusion that “decentralisation and socialism go hand in hand, and capitalism is in opposition to decentralisation”. If you had said laissez faire capitalism, I might be more inclined to agree, but even then, what if it is laissez faire capitalism within a socialistic regime, i.e. fascism? The decentralization half of your conclusion goes to hell in a hand basket. The main problem here is that apples are difficult to compare to oranges to begin with.

Decentralization = democracy IMVHO. Now, how we organize the economic system within that is another topic, but I will say that the American democracy never did better than when there were antitrust laws, i.e. laws that furthered decentralization of the mean of production and punished the opposing idea of centralized monopolistic behavior.

Whew! A lot said in record time, and extremely deficient as a result, I'm sure – I almost didn’t say anything, but, what the hell, that’s why we’re here and it’s what I hope others will do with what I post, so I decided to make my simplified, generalized attempt too. 😃