International Relations. A self-Study Guide to Theory

Part II: new liberal theory in International Relations. 
Within the discipline, a great deal of controversy exists concerning the 
term “liberal theory”. You will become aware of a variety of usages when 
you have taken a closer look at the textbooks, where you will find such dif-
fering “labels” for liberal theory as, “domestic theories of international poli-
tics” (Putnam 1988), “theories of state-society relations” (Moravcsik 1993), 
“pluralism” (Viotti/Kauppi 2005), “second image approach” (Waltz 1959) or 
“reductionist theories” (Waltz 1979).
From our discussions in unit 5 (neorealist theory), you are already famil-
iar with the basic criticism of “reductionist” approaches as expressed by 
Waltz as well as with core neorealist arguments on why a theory of interna-
tional politics should be a system-level theory. From the conceptual tool 
“levels of analysis” introduced in unit 4, we know that “reductionist” theories 
provide explanations for outcomes in international politics at the level of the 
state. They do so by drawing attention to explanatory factors at the unit level, 
i.e. to all the “attributes”, which Waltz suggested we omit in order to con-
struct a system-level theory. Taking the neorealist perspective as the starting 
point, liberal approaches would fall into this group of “reductionist” theories. 
Liberal thinking has a long intellectual tradition. The term “liberal” points 
to the roots of liberal theory in the European Enlightenment, as well as to the 
liberal theory of politics/political liberalism. Immanuel Kant (The perpetual 
peace, 1795), already known to us as an intellectual precursor of institution-
alist thinking in International Relations, also belongs to the “liberal tradi-
tion”. Kant believed that a “republican constitution” of states is the first and 
most important requirement for stable and peaceful inter-state relations. We 
will come back to his arguments when discussing the (liberal) theory of inter-
democratic peace. The core argument here is one of a causal link between a 
liberal type of political order within the state and that state’s foreign policy 
and international politics. Peace and international cooperation as outcomes of 
international politics are more likely to exist among states with a liberal do-
mestic order. Other well-known contributors to liberal theory in international 
economics and international politics are Adam Smith, John Stuart Mill and 
Woodrow Wilson. In their philosophical, economic and political thinking, 
these “liberals” drew important conclusions about the relationship between 
internal (domestic) factors and foreign policy behavior. What the intellectual 
precursors of liberal theory had in common was a normative perspective that 

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a “civilization of international politics” was desirable and societal progress 
possible. For this reason, they have often either been acclaimed as “idealists” 
or have had their approaches labeled as “utopian”, in particular by the realist 
“camp”. Owing to these intellectuals’ strong normative commitments, which 
sometimes come close to political ideology, social science has not really clas-
sified their work as “theories”. 
However, liberal theory in the 20
th
and 21
st
century has been built explic-
itly on these early ideas. Attempts have been made to develop coherent theo-
retical programs in accordance with the dominant positivist ideal in social 
science. The label “liberal”, in the most basic understanding, encompasses 
those theories that explain outcomes of international politics by referring to 
domestic actors, structures and processes. It goes back to neofunctionalism 
as a theory of regional integration (Ernst Haas), the work of Graham T. Al-
lison on bureaucratic politics (Allison 1971), the transnationalist theory of 
Keohane/Nye and the early works of James Rosenau. Bruce Russett, Michael 
Doyle, Robert Putnam, Peter J. Katzenstein, and Andrew Moravcsik also 
made important contributions to liberal theory in contemporary International 
Relations. In the German-speaking world, the works of Ernst Otto Czempiel 
(1979, 1981) and Thomas Risse are associated with a liberal perspective on 
international politics. What these works have in common is a pluralist, liberal 
conception of state and society.
However, liberal theory in IR is diverse and different strands of contem-
porary liberal theory can be distinguished by the particular factors that are 
expected to shape foreign policy behavior. Zacher/Matthew (1995: 120-137), 
for example, distinguish republican liberalism, commercial liberalism, mili-