Introduction
Stephen William Van Evera (born 10 November 1948) is a professor of Political Science at the Massachusetts Institute of Technology, specializing in International Relations. His research includes the U.S. foreign and national security policy and causes and prevention of war. He is a member of the Council on Foreign Relations.
Biography
Van Evera received his A.B. in government from Harvard and his Ph.D. in political science from the University of California, Berkeley. During the 1980s he was managing editor of the journal International Security.
Van Evera is the author of Causes of War: Power and the Roots of Conflict (Cornell, 1999). He has also co edited Nuclear Diplomacy and Crisis Management (1990), Soviet Military Policy (1989), and The Star Wars Controversy (1986).
Academic work
Van Evera is considered a defensive realist, which is a branch of structural realism.
Offense-defense theory
In Causes of War: Power and the Roots of Conflict, Van Evera proposed Offense-Defense theory, which attempts to discern what factors increase the likelihood of war. Van Evera states three main hypotheses: 1. War will be more common in periods when conquest is easy, or is believed to be easy, than in other periods. 2. States that have, or believe they have, large offensive opportunities or defensive vulnerabilities will initiate and fight more wars than other states. 3. Actual examples of true imbalances are rare and explain only a moderate amount of history. However, false perceptions of these factors are common and thus explain a great deal of history.
The causes of World War I provide a good example of Van Evera’s theory in action. Although trench warfare, poison gas, and the development of the machine gun and air support meant that defensive strategies should have prevailed, many European nations were under the illusion that conquest was easy or that they were valuable. This misconception resulted in a drawn-out, bloody conflict. Recent discussion in international relations theory withdraws the idea of explaining outbreak of World War I. with the offense-defense balance.