Never at War: Why Democracies Will Not Fight One Another is a book by the historian and physicist Spencer R. Weart published by Yale University Press in 1998.
The book classifies human societies into four broad groups: A borderline case is the Athenian democracy, which excluded metics and slaves.
Weart uses a broader definition of war than is usual in his research on the democratic peace theory and includes any conflict causing at least 200 deaths in organized battle by political units against one another.
He requires the democracies and the oligarchies to have tolerated dissent for at least three years since he finds that time to be necessary for a political culture in a nation to change and to be reflected in foreign policy.
Weart argues that the only clear case of war between oligarchies is a 1656 battle between Bern and Lucerne, which was caused by religious fervor during the Reformation.
The War of the Pacific may be another, but both Chile and Peru had strong anocratic tendencies in which family and personal loyalty formed much of the power base of the leaders.
The democratic and oligarchic peace are also strengthened by the culture of arbitration and the respect for the ingroup opposition in both democracies and oligarchies.
Earlier democracies and oligarchies did not include non-Europeans in the ingroup since they perceived them to be racially inferior and to be living in autocracies and anocracies.
The autocratic leaders misunderstand the conciliatory methods used by democracies and oligarchies and see it as an admission of weakness that can be exploited with little risk.
For example, during the early part of the 20th century the United States sent soldiers to many nations in Central America to hold free elections but with little long-term success.
The attempts that succeeded, like occupied Japan after World War II, involved drastic change of the whole political culture.
Weart argues that it is generally better to spread democracy by diplomacy and by slowly promoting internal political change.
Especially by looking at many ambiguous cases, it is possible to sift out a set of features that decide if a pair of regimes makes war or avoids it.
Also, many modern classicists agree that Rome and Carthage were oligarchic republics, "which suggests that excluding them was a largely arbitrary judgment that just happened to leave Weart's central claim intact.
Some democratic peace researchers have excluded the states in Ancient Greece because of the limited franchise and the use of allotment to select many government leaders.
Critics argue that there is no ancient evidence for this perception and that the major source on Syracuse democracy is Thucydides, an Athenian.
Help from an inside group was essential since the Greeks lacked effective siege machinery, and the expedition was ill-suited for the alternative, a long wait to starve the defenders.
JM Owen, in a generally friendly review, questions Weart's conclusion that universal democracy will mean lasting peace.
For example, a game-theoretic explanation for the democratic peace is that the public and the open debate in democracies send clear and reliable information regarding the intentions to other states.