Marxists
Immanuel Wallerstein
Production for sale in a market in which the object is to realize the maximum profit is the essential feature of a capitalist world-economy. “In such a system production is constantly expanded as long as further production is profitable, and men constantly innovate new ways of producing things that will expand the profit margin”
David Harvey
Capitalism in terms of three features: it is growth-oriented (“a steady state of growth is essential for the health of a capitalist economic system”); “growth in real values rests on the exploitation of living labor in production;” and it is “necessarily technologically and organizationally dynamic.” (The Condition of Postmodernity page 180)
Minarchists
Milton Friedman
The possibility of co-ordination through voluntary co-operation rests on the elementary – yet frequently denied – proposition that both parties to an economic transaction benefit from it, provided the transaction is bi-laterally voluntary and informed. Exchange can therefore bring about co-ordination without coercion. A working model of a society organized through voluntary exchange is a free private enterprise exchange economy – what we have been calling competitive capitalism.”
Ayn Rand
“A social system based on the recognition of individual rights, including property rights, in which all property is privately owned.” – “In a capitalist society, all human relationships are voluntary. Men are free to cooperate or not, to deal with one another or not, as their own individual judgments, convictions and interests dictate.”