• Check spiral
• Alliances make war MORE likely
o They generate counter alliances and arms races
o Audience costs
o Permanent alliances reduce the number of potential coalitions against the aggressors
o Selection cost
States select themselves into alliances when they feel they are going to war.
• Alliances: a formal agreement among a limited number of countries concerning the conditions under which they will or will not employ military force.
• Types of Alliances:
o Defense pact
Only if you’re attacked.
o Neutrality/ non aggression pact
Will stay neutral at all times. Not one or the other.
• Some Empirical Findings
o Levy (1981) found that most alliances are followed by war
o Siverson and King (1979) show that alliances lead to the expansion of smaller wars into larger ones.
o Bremer (1992) found that allies are more likely to fight because that are most likely to be neighbors
Highly militarized allies are more likely to fight each other.
Allies are more likely to fight each other.
• The Jack Levy’s Study
o He focuses on Great Powers (GP) from 1495-1975
o Interstate wars involving at least one GP.
(119 total, 64 with GP’s on both sides)
o Question: Are alliances necessary and /or sufficient for war?
• Number of Alliances Over Time ****GET GRAPH***
16th cent. 17th 18th 19th
• Sufficient Condition
o Every X (alliance) will be followed by Y (war)
o Some wars may occur when there is no X (alliance)
• Necessary Condition
o Every war (Y) will be preceded by an Alliance (X)
o Some alliances (X) may not lead to war.
• Levy’s Conclusions
o Most alliances were followed by war within 5 years (except the 19th century)
Thus alliance is a near sufficient condition for war in most centuries
o However, most wars were not preceded by alliances
Alliances are not a necessary condition for war.
• Table 1.8