1. Alliances and War V&H, Chapter 1 (Levy)

2. Introduction Alliance: A formal agreement among a limited number of countries concerning the conditions under which they will or will not employ military force.

3. COW Alliance Types • Defense pact • Neutrality/Non-aggression pact • Entente

4. Alliance-War Relationship • Alliances make war less likely • Balance of Power theory • Deterrence • They reduce uncertainty

5. Alliance-War Relationship • Alliances make war more likely • They generate counter alliances and arms races • Audience costs • Permanent alliances reduce the number of potential coalitions against the aggressors

6. Empirical Findings • Alliances were associated with peace in the 19th century, but war in the 20th century • Alliances make the expansion of war more likely • Allies are not reliable during war (Sabrosky); allies are reliable during war (Leeds, Long, and Mitchell)

7. Jack Levy’s Study • He focuses on Great Powers (GP) from 1495-1975 • Interstate wars involving at least one GP (119 total, 64 with GP’s on both sides) • Question: are alliances necessary and/or sufficient conditions for war?

8. Number of Alliances Over Time Century 16th 17th 18th 19th 20th Total # of alliances 5 9 15 25 65 119 # of GP 4 5 14 14 40 47 alliances % GP alliances 80% 56% 93% 56% 15% 39%

9. Necessary Condition • Every war (Y) will be preceded by an alliance (X) • Some alliances (X) may not lead to war

10. Necessary Condition

11. Sufficient Condition • Every X (alliance) will be followed by Y (war) • Some wars may occur when there is no X (alliance)

12. Sufficient Condition

13. Levy’s Conclusions • 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 • However, most wars were not preceded by alliances • Alliances are not necessary conditions for war

14. Alliance Reliability • Do alliance partners come to each other’s aid in war? • Allies do what they promise 75% of the time (Leeds, Long, Mitchell)