A Test for Reverse Causality in the Democratic Peace Relationship
| Author | Michael Mousseau,Yuhang Shi |
| Date | 01 November 1999 |
| DOI | 10.1177/0022343399036006003 |
| Published date | 01 November 1999 |
| Subject Matter | Articles |
A Test for Reverse Causality in the Democratic Peace
Relationship*
MICHAEL MOUSSEAU
Department of International Relations, Koç University
YUHANG SHI
Department of Political Science, East Carolina University
Several studies have suggested the possibility of reverse causation in the ‘democratic peace’ relationship:
that the well-known extreme rarity of wars between democratic nations may be partially or wholly
explained by a negative impact of war on democracy. Three kinds of war-on-regime effects are dis-
cussed. Anterior effects are regime changes that occur in preparation for wars; concurrent effects are
those that occur during the course of a war; and posterior effects are regime changes that occur after a
war concludes. Because studies have shown that democratic nations are rarely, if ever, on opposite sides
in wars at their start, it is argued that reversed causation may affect the presence of causation from
democracy to peace only if nations tend to become more autocratic as they prepare for impending wars.
This proposition is examined with the observation of war events involving geographic neighbors or
major powers, worldwide, from 1816 to 1992. With interrupted time-series analysis, it is found that
nations are about as likely to become more institutionally autocratic as they are to become more demo-
cratic in the periods before the onset of wars. Moreover, this pattern holds even for the smaller subset
of nations estimated to be democratic in the periods before major wars. These results indicate that
studies of regime type and war participation have not been underspecified due to possible reverse cau-
sation before the onset of wars, and thus support the notion that the direction of causation in the
democracy and war relationship is unidirectional from democracy to peace.
The Democracy–Peace Nexus
Empirical research has firmly established
that democratic nations very rarely engage
each other in war, and this pattern is highly
unlikely to be attributable to chance. While
democracies do clearly engage in wars
against other states, the absence of wars
between democratic nations has attracted a
great deal of attention in recent years, gener-
ating dozens of published articles and at least
three special symposia in leading journals.
This attention is warranted, as the ‘demo-
cratic peace’ offers the remarkable prospect
that a world of democratic nations may be a
world at interstate peace. The impact of
democracy on war has become even more
relevant in the wake of the Cold War and
* An earlier version of this article was presented at the
1996 Annual Meeting of the American Political Science
Association, San Francisco. For helpful comments and
insights the authors wish to thank Stuart A. Bremer, Nils
Petter Gleditsch, Patrick James, Michael McDonald,
Sara McLaughlin Mitchell, Eric Solberg, William R.
Thompson, Michael Ward, and the anonymous referees
from JPR. Of course, all views and errors are the authors’
own. The data used in this article can be obtained from:
http://personal.ecu.edu/shiy/peace/peace.htm.
639
journal of
peace
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ESEARCH
© 1999 Journal of Peace Research
vol. 36, no. 6, 1999, pp. 639–663
Sage Publications (London, Thousand
Oaks, CA and New Delhi)
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the consequent diffusion of democratic gov-
ernment around the globe.
While numerous studies have engaged in
introducing and examining potential expla-
nations for the democratic peace (e.g. Bueno
de Mesquita & Lalman, 1992; Dixon, 1994;
Maoz & Russett, 1993), its policy implica-
tions (e.g. Ray, 1997; Russett, 1993),
and wider aspects of democratic foreign
behavior (e.g. Mousseau, 1997, 1998a;
Simon & Gartzke, 1996), a seemingly
growing number of studies have alluded to
the possibility of reverse causation in the
democratic peace relationship (e.g. Gates et
al., 1996; James et al., 1999; Midlarsky,
1995; Thompson, 1996; Wolfson et al.,
1998). The notion of endogeneity means
simultaneous causation: that war has a nega-
tive impact on democracy while, at the same
time, democracy has a negative impact on
war. If this second aspect of causation exists
in the democracy and war relationship, then
previous studies of regime type and war par-
ticipation have been underspecified. This
means that the effect of democracy on war
may be less than the current evidence sug-
gests, and the possibility exists of full
‘reverse’ causality: that a negative impact of
war on democracy may explain the demo-
cratic peace (Layne, 1994: 44–45).
We believe the notion of reverse
causality should not be taken lightly. If
the path of causation is unidirectional and
runs from peace toward democracy, then
all the attention given the democratic
peace is unwarranted, and the prospect of
interstate peace through global democrati-
zation is an idealist’s dream. Given the
dramatic implications of the democratic
peace, it is therefore appropriate to
consider all room for doubt in the
relationship, including the possibility of
reverse causality. However, we are also
aware that if a thesis is stated often
enough it may become perceived as true,
with or without evidence. Particularly
disturbing is the prospect that continuing
references to the possibility of reverse
causality in the empirical literature may
falsely render the democratic peace as
inconsequential in policymaking circles.
As Chan recently stated, ‘it is important
for the research community to take
seriously the possibility of reverse
causality’ (Chan, 1997: 84). We agree
with Chan, and undertake this study to
examine the viability of the ‘reverse
causality’ hypothesis concerning the demo-
cratic peace.
As will be discussed in this article, it is the
prospect that nations tend to autocratize as
they prepare for wars that poses the plausible
challenge to the presence of causality from
joint democracy to peace. We thus employ
an interrupted time-series analysis to esti-
mate the impact of impending war on the
regime status of nations. This method allows
us to assess the degree to which wars affect
political changes before their onset, apart
from the impact of such political changes on
war involvement. Our aim is thus limited to
examining the reversed arrow of causation
from war to autocracy. If we find that wars
do affect governing institutions before their
onset, then further study will be needed to
assess the degree to which this reverse
direction of causation may affect the impact
of democracy on war onsets. The article
begins with a survey of recent challenges to
the democratic peace and the prospects for
reverse causality, followed by a review of
our research design which is aimed at exam-
ining the presence of causality from war to
autocracy.
The Reaffirmation of the Democratic
Peace
The extreme rarity of joint democratic war,
after a century of democratization across the
globe, has made it statistically improbable
that the democratic peace has occurred by
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