Realism (and Neorealism) 81therefore propose general laws to explain events: they simplify explanations of be hav
ior in anticipation of being better able to explain and predict trends.
Neorealists give pre ce dence in their analyses to the structure of the international
system as an explanatory factor, while traditional realists also attach importance to the
characteristics of states and human nature. According to Waltz, the most impor tant
object of study is the structure of the international system. Attempting to understand
the international system by reference to states is analogous, in Waltz’s view, to attempt
ing to understand a market by reference to individual firms: unproductive at best.
Neorealism thus advances two normative arguments and one theoretical. The first nor
mative argument is that we need theory to understand international politics (and that
prior to the publication of Waltz’s book, we had none), and the second is that his theory,
neorealism, explains international politics since 1648, the date scholars cite for the
advent of the state system. Waltz’s theoretical argument is that the amount of peace
and war in an anarchic international system depends critically on the distribution of
power, described in terms of system structure.
Critics of classical realism noted that if the human desire for power, inscribed on
states, was driving the recurrence of interstate war, how could we explain long periods
of peace? Waltz argued that the distribution of power in the international system can
be described as having one of three pos si ble forms: (1) unipolar (where one state in the
system has sufficient power to defeat all the others combined against it; we’ve never
seen a true unipolar situation); (2) bipolar (where most of the system’s power is divided
between two states or co ali tions of states; as between Rome and Carthage, or Athens
and Sparta); and (3) multipolar (in which power is divided among three or more states
or co ali tions of states, as in Eu rope in 1914). Thus, according to neorealists, the structure
of the system and the distribution of power within it, rather than the characteristics of
individual states, determine outcomes. This is why, in the neorealist view, the closer
the overall distribution of power approaches unipolarity, the greater the likelihood (but
never the certainty) of peace.^9
This observation leads to another key question, the answers to which lie at the root
of the disagreement between liberals and realists. Why, we might ask, have not two or
more great powers ever cooperated to become a single leviathan, thus ending war? Neo
realists posit two answers: first, cooperation is difficult under conditions of anarchy
due to concerns over relative gains; and second, states in an anarchic system must be
on constant guard against cheating.
The importance of relative power means that states hesitate to engage in cooperation
if the benefits to be gained might be distributed unevenly among participating states.
For example, if you and I are trading partners, and after each trade I gain $3.00 and you
gain $1.50, we both gain in absolute terms. But, over time, I will accumulate more cash
than you will; I might then use my advantage in wealth to coerce you. In a neorealist’s