Kenneth E. Boulding Quotes
[The historical] development in the international system may almost be defined as the process by which we pass from stable war to stable peace.
Boulding, Kenneth E. Stable Peace. University of Texas Press, 1978, p. 13.
This seems to be the origin of the notion that democracies and republics are less likely to war with others than monarchies or dictatorships.
Actually it was the United States which insisted in the veto which required consensus of the great powers of the time. It was Russia which ended up using it far more often than any other nation.
Kenneth Ewart Boulding was an English-born American economist, educator, peace activist, and interdisciplinary philosopher. Boulding was the author of two citation classics: The Image: Knowledge in Life and Society (1956) and Conflict and Defense: A General Theory (1962). He was co-founder of general systems theory and founder of numerous ongoing intellectual projects in economics and social science. He was married to sociologist Elise M. Boulding.