International Relations. A self-Study Guide to Theory

Political structures: national and international 
 National 
political 
system 
International political 
system 
Ordering principle 
Hierarchy
Anarchy
Functional differentiation 
of units 
 
Yes 
No. Like units. States as sov-
ereign political units and 
unitary actors.
Distribution of 
capabilities across units 
Distribution of power as a 
“structural feature” of the 
political system. 
Distribution of power as a 
“structural feature” of the 
system. Change in the dis-
tribution of power is a 
change in the system. 
3.3. Structures as causes 
For a system theory of international politics, political structures have to be 
defined in a way that enables an identification of their causal effects. “Causal 
effects” of structures means that the structure of the system “acts” as a con-
straining and disposing “force”. Actions of agents and agencies, their interac-
tions and the outcomes of their interactions are all affected by the system’s 
structure. Outcomes in international politics cannot be inferred from the in-
tentions and behaviors of the units (“inside” states), but have to be explained 
in reference to the “external” structures. They can only be explained struc-
turally. Effects vary as structures change.
For Waltz, a structural realist explanation (that is, through his concept of 
structure) is the only way to answer the core question of neorealist theory: 
why do recurrent patterns of state behavior and repeated and enduring pat-
terns in the history of international politics, cycles of war and peace, and pe-
riods of conflict and stability in the international system occur? An explana-
tion in neorealist theory is to say why patterns of behavior recur, why events 
repeat themselves, why the range of expected outcomes falls within certain 
limits (Waltz 1979: 69). Recurrences and repetitions within a system cannot 

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be explained by reductionist theories. It is a constancy of structure that ex-
plains the recurrent patterns and features of international politics. 
For Waltz, a structural realist theory can explain why war recurs and de-
fine conditions that make war more or less likely, but it will not predict the 
outbreak of particular wars. According to Waltz, structures explain some 
“big, important and enduring patterns” (Waltz 1979: 70). These are the conti-
nuities within a system. Phases of stable international systems and phases of 
conflict and war are the “big and important” patterns. It is not the objective to 
explain single, particular events and short-term outcomes in international pol-
itics. This is the domain of theories at the state level. 
The core question therefore is: What are the causal effects of an anar-
chical structure of the system and of a specific distribution of capabilities? 
Here Waltz draws on an analogy: he uses the theory of the market to explain 
how the structure of the international system shapes the behavior of states in 
the same way that the market forces of a competitive market economy shape 
the behavior of the single firms.