Capitalism is based on rules of property and ownership, basically that I can own something, that you can't take it away from me through violence and that I can hire people to improve that something and they won't have an ownership stake on it (unless I want them to.) Those rules come from government. If you think about a society with no centralized rules on property and ownership, it wouldn't be very capitalistic, it would be much more like an anarchic steal-what-you-can system.
Those rules regarding property and ownership predate government. The government likes to pretend that only it can enforce those rules, when in fact it is the entity most responsible for violating them. You can't seriously claim to enforce property rights when you yourself are seizing a sizable chunk of everyone's income for your own use. Also, there is no reason at all that the rules need to be "centralized" or promulgated and enforced by some special class of rulers. Property and ownership and the justice of proportional punishment for violating them are all logical consequences of self-ownership and reciprocation. People are perfectly capable of arranging to enforce their own rights without depending on an overgrown, overpriced, centralized protection racket.
