In Chapter 3, Essentials of International Relations presents several major “theoretical lenses” with which to understand world politics. Each of these lenses directs attention to different actors, problems, dynamics, causes, and effects. Each is also a simplification of reality, highlighting a part of world politics in order to describe and explain key patterns and predict behavior and outcomes. In this exercise, you will review the main theoretical lenses and how they highlight different aspects of world politics, paying special attention to the events and explanations they emphasize.

I. Concepts. Review the main features of Liberalism, Realism, Radicalism, and Constructivism, using the summary table on page 79 as a point of departure for the more thorough description in the text.

II. Finding Patterns and Explanations.

Return to chapter 2 and its historical overview of world politics. Note that it is divided into historical periods: pre-Westphalia; Westphalia, nineteenth-century Europe; Interwar and World War II; The Cold War; and the Post–Cold War. For each of these historical periods, identify the key actors, events, and dynamics that you believe each theoretical lens would highlight. Use the information grid below to collect and organize your findings.

HISTORICAL PERIOD	REALISM	LIBERALISM	RADICALISM	CONSTRUCTIVISM
PRE-WESTPHALIA
WESTPHALIA
NINETEENTH-CENTURY EUROPE
INTERWAR AND WORLD II
COLD WAR
POST-COLD WAR

III. Conclusions and Implications. Study the information you have collected, and consider the following questions:

a. What behavior does each theory explain best?
b. What behavior does each theory miss?
c. Is there a “best” theory? Why or why not?
d. What conclusions can you draw about international relations theory and our understanding of world politics?