Democracy and armed conflict
Håvard Hegre
Department of Peace and Conflict Research, Uppsala University
& Peace Research Institute Oslo (PRIO)
Abstract
The article reviews the literature on the relationship between democracy and armed conflict, internal as well as interstate.
The review points to several similarities between how democratic institutions affect both conflict types. It summarizes
the main empirical findings and discusses the most prominent explanations as well as the most important
objections raised to the finding, empirically and theoretically. To a large degree, the empirical finding that pairs
of democratic states have a lower risk of interstate conflict than other pairs holds up, as does the conclusion that
consolidated democracies have less conflict than semi-democracies. The most critical challenge to both conclusions
is the position that both democracy and peace are due to pre-existing socio-economic conditions. I conclude that this
objection has considerable leverage, but it also seems clear that economic development is unlikely to bring about
lasting peace alone, without the formalization embedded in democratic institutions.
Keywords
democracy, development, internal conflict, interstate conflict
Introduction
The idea that democracies rarely if ever fight each other is
often traced back to Immanuel Kant (1795/1991). The
citizens of a (democratic) republic will hesitate before
embarking on a war, for ‘this would mean calling down
on themselves all the miseries of war’ (p. 100).1
The
modern debate on the ‘democratic peace’ surged from
the obscurity of the Wisconsin Sociologist (Babst, 1964)
during the Cold War to a place of prominence in international
relations around the turn of the millennium. By
that time, there was a consensus that democracies do not
fight each other in interstate wars. In parallel with the
establishment of empirical evidence for an interstate
democratic peace, several studies also indicate that democratic
states have less frequent domestic armed conflicts.
The argument that democracy causes peace has important
implications, and may even have profoundly
influenced US policies in the buildup to the 2003 Gulf
War (Owen, 2005; Gat, 2005; Russett, 2005).
The democratic peace debate fundamentally influenced
IR scholarship also beyond its substantive importance.
It brought a major shift toward the acceptance of
large-N statistical studies within IR, as represented by the
seminal designs of Bremer (1992) and Maoz & Russett
(1992). Along with the studies of the more general ‘liberal
peace’, the debate stimulated the introduction of several
methodological innovations within the field, such as the
treatment of reverse causation or temporal dependence.
Much of this innovation was stimulated by the emerging
practice of posting replication datasets, pioneered by JPR
and scholars such as John Oneal and Bruce Russett.2
Below, I summarize the empirical evidence for the
interstate and domestic peace propositions and the main
theoretical arguments explaining them, and note the most
1
Several other enlightenment theorists precede Kant in arguing that
states founded on democratic principles must also be against war
(Gates, Knutsen & Moses, 1996: 6–7).
2
See Dafoe, Oneal & Russett (2013) for a summary of this
productive practice.
Corresponding author:
havard.hegre@stv.uio.no
Journal of Peace Research
1–14
ª The Author(s) 2014
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DOI: 10.1177/0022343313512852
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important objections. Several similarities between the two
forms of the democratic peace emerge. This is particularly
true for what I see as the most critical challenge to the
democratic peace, namely that both democracy and peace
are due to pre-existing socio-economic conditions. This
objection has considerable leverage, but it also seems clear
that these conditions are unlikely to bring about lasting
peace alone, without democratic institutions.
Main empirical findings
The interstate democratic peace
The interstate democratic peace has been studied at several
‘levels of analysis’ (Gleditsch & Hegre, 1997). At the
dyadic level, there is considerable agreement that the
‘absence of war between democratic states comes as close
as anything we have to an empirical law in international
relations’ (Levy, 1989: 270).3
Important studies in favor
of the proposition are Rummel (1983), Doyle (1983,
1986), and a string of studies by Bruce Russett and coauthors
(e.g. Maoz & Russett, 1992, 1993; Russett &
Oneal, 2001). Following the review of Gleditsch
(1992), JPR became a major outlet for the debate.4
The
dyadic finding has to a large degree withstood a series of
counter-arguments. I discuss these in detail below.
There is less compelling evidence for democratic
countries being less warlike overall – the ‘monadic’ level
of the democratic peace. The bulk of the early large-N
studies (e.g. Small & Singer, 1976; Weede, 1984), agree
with Chan (1984) who found that ‘relatively free’ countries
participated in war just as much as the ‘less free’.
Gleditsch & Hegre (1997) show that democracies rarely
initiate wars, and Hegre (2008) that they are more peaceful
overall when controlling for their military potential.
Research at the system level has recently attracted
renewed attention.5
Gleditsch & Hegre (1997) suggest
that a world with an intermediate share of democracy
may be associated with more war since the probability
of war on average is highest in dyads with one democracy
and one non-democracy. However, an increase in the
proportion of countries that are democratic may alter the
dyadic and monadic probabilities as systemic democratization
affects international interactions (Russett, 1993;
Huntley, 1996; Mitchell, Gates & Hegre, 1999; Kadera,
Crescenzi & Shannon, 2003). Cederman (2001)
rephrases the standard account of Kant (1795/1991),
seeing the development of the democratic peace as a dialectic
process where states gradually learn to form (democratic)
pacific unions. He shows that the risk of war
between democracies has been falling over the past two
centuries. The risk of non-democratic war has also
declined, but less swiftly. Relatedly, Mitchell (2002)
shows that non-democracies in the Americas became
much more likely to settle territorial claims peacefully
when the proportion of democracies in the system
increased. Gartzke & Weisiger (2013), on the other
hand, argue that regime type becomes a less salient indicator
of ‘otherness’ as more states become democratic,
and their empirical analysis indicates that the risk of conflict
between democracies has increased as the world has
become more democratic.6
Studies using tools of network analysis also indicate
systemic effects of democracy. Dorussen & Ward
(2010) and Lupu & Traag (2013) find support for the
democratic peace while accounting for the pacifying
impact of trade networks. Maoz (2006) finds that large
‘democratic cliques’ in networks dampen conflicts, but
Cranmer & Desmarais (2011) conclude that the support
for this claim is weak when using a more appropriate statistical
method.
The internal democratic peace
A number of studies find empirical confirmation of an
‘inverted-U’ relationship between level of democracy and
the probability of onset of internal armed conflict. Semidemocratic
regimes have a higher risk of internal conflict
than consistent autocracies or democracies (Boswell &
Dixon, 1990; Muller & Weede, 1990; Hegre et al.,
2001; Fearon & Laitin, 2003). The existence of this
‘inverted U’ has been challenged, however (Elbadawi &
Sambanis, 2002; Collier & Hoeffler, 2004; Vreeland,
2008).7
In any case, very few studies find traces of a monotonic
effect of democracy. When controlling for GDP per
capita or other indicators of socio-economic development,
democratically governed countries have no lower risk of
internal armed conflict than autocratic ones.8
3
The ‘dyadic level’ refers to interactions between two countries; the
‘monadic level’ to the behavior of single countries.
4
Also see the reviews of the dyadic and monadic democratic peace in
Ray (1993), Gleditsch & Hegre (1997), and Russett (2009).
5
See Harrison (2010) and Snyder (2013) for recent reviews.
6
The empirical analysis in Gartzke & Weisiger (2013) is contested in
Dafoe, Oneal & Russett (2013), however.
7
See Gleditsch, Hegre & Strand (2009), including a discussion of
whether one should control for the stability of institutional
constellations.
8
One partial exception is Cederman, Wimmer & Min (2010) who
find that systematic exclusion of ethnic groups from political power
increases the risk of conflict.
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Buhaug (2006) finds that semi-democracies have a
higher risk of wars over government than autocracies and
democracies, but that democracies are more likely to
experience conflicts over territory than the other two
regime types. Cederman, Hug & Krebs (2010) find
democratization to affect conflicts over government, but
not over territory.
Although democratic institutions by themselves are
ineffective in reducing risk of internal conflict onset, several
studies find that they affect how internal conflicts
evolve. Lacina (2006) and Gleditsch, Hegre & Strand
(2009) show that internal wars in democracies are less
lethal. Democratic governments make use of less violence
against civilians (Eck & Hultman, 2007) and engage in less
repression (Davenport, 2007b; Colaresi & Carey, 2008),9
but rebel groups tend to make more extensive use of violence
against civilians when fighting democratic regimes
(Eck & Hultman, 2007). Possibly because of the stronger
constraints on the use of violence against insurgents,
democracies tend to have longer internal wars (Gleditsch,
Hegre & Strand, 2009).10
Some studies, such as Mukherjee (2006), find that
post-conflict democracies have a lower risk of conflict
recurrence. Other studies report contrasting results
(Walter, 2004; Quinn, Mason & Gurses, 2007; Collier,
Hoeffler & So¨derbom, 2008).
Explanations
Interstate conflict
Although there is scholarly agreement that democracies
rarely if ever have fought each other, there is less consensus
as to why. The following five sets of explanations are
important:
First, the normative explanation (Doyle, 1986; Maoz &
Russett, 1993) holds that ‘the culture, perceptions, and
practices that permit compromise and the peaceful resolution
of conflicts without the threat of violence within
countries come to apply across national boundaries
toward other democratic countries as well’ (Ember,
Ember & Russett, 1992: 576). States ‘externalize’ the
domestic norms that encourage compromise solutions and
reciprocation, and strictly inhibit the complete removal
from political life of the loser in political contest.
The absence of a monadic democratic peace is troublesome
for the normative explanation, in particular
since it implies that the probability of conflict between
democracies and non-democracies must be higher than
that between two non-democracies (Raknerud & Hegre,
1997). Rosato (2003) points to the frequent violation of
liberal norms when democracies have decided to go to
war – in imperial wars, as well as in frequent US interventions
intended to overthrow democratically elected
governments (Rosato, 2003: 589–590).11
Another notable
caveat noted as early as in Kant (1795/1991), is the
incentive to intervene in non-democracies to press for
democratization (Peceny, 1999; Gleditsch, Christiansen
& Hegre, 2007). A particularly critical view of democratic
war behavior is found in Geis, Brock & Mu¨ller
(2006).
Second, according to the legislative constraints explanation,
democratic leaders are constrained by other bodies
(such as parliaments) which ensure that the interests
of citizens and powerful organizations are taken into
account. Debate is public, so information on the real
costs of war is likely to enter the decision calculus. Democratic
political leaders will be removed from office if
they circumvent these constraints.12
Democracies’ ability to signal resolve is a third explanation.
Why are states not able to agree to a solution that
reflects the distribution of power and the actors’ ‘resolve’,
without incurring the costs of war (Fearon, 1995)? One
answer is that if crisis escalation is not very costly, both
parties have an incentive to exaggerate their power or
resolve, mobilize, and back down when the bluff is discovered.
Fearon (1994) argues that audience costs – the
costs that a leader suffers when backing down – lock
leaders into their positions, increasing the costs of bluffing.
Democracies have higher audience costs, Fearon
argues, and may more credibly commit to policies with
little crisis-inducing behavior to signal intentions.13
Making use of various empirical strategies to distinguish
the explanations, Schultz (1999) and Prins
(2003) find stronger support for the signaling argument
than for the constraints explanation. Weeks (2008)
builds on this argument by showing that single-party
regimes also indicate behavior in line with a signaling argument.
Downes & Sechser (2012), Snyder & Borghard
(2011), and Trachtenberg (2012), on the other
9
See Davenport (2007a) for a comprehensive review.
10
Collier, Hoeffler & So¨derbom (2004), Fearon (2004), and
DeRouen & Sobek (2004), on the other hand, find no link
between regime type and duration of conflict.
11
Also see Downes & Lilley (2010). Rosato’s argument was
countered by Kinsella (2005) and other contributions in the same
issue of APSR.
12
See Choi (2010) for empirical support for this explanation.
13
The audience cost and legislative arguments arguably also imply a
monadic democratic peace.
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hand, find little empirical evidence for the audience
cost argument.14
Fourth, in a mobilization argument Bueno de Mesquita
et al. (1999, 2003) argue that the democratic re-election
pressures on leaders tend to make them more careful to
select only wars they are likely to win, and to mobilize
more resources for the war efforts they select than do autocratic
leaders. This makes democracies unattractive targets,
since they are likely to win the wars they fight
(Reiter & Stam, 1998).15
Both of these tendencies tend
to reduce the probability of war between democracies.
One aspect of the effectiveness of democracies in war
is their ability to form large alliances in important wars
(Doyle, 1986; Raknerud & Hegre, 1997). The empirical
analysis in Gartzke & Gleditsch (2004), however, suggests
that democracies are less reliable allies. Leeds,
Mattes & Vogel (2009), on the other hand, find that
countries with democratic institutions are much less
likely to abrogate international commitments than autocratic
countries in instances where domestic leadership
transitions result in leaders with different primary bases
of societal support.
Fifth, Gartzke (1998) points out that the democratic
peace finding might be due to joint interests. Democracies
may fail to disagree sufficiently on international policies
to be willing to suffer the costs of war. Such joint
interests may be due to the fact that most democracies
were on the same side during the Cold War (Farber &
Gowa, 1995).16
The failure to observe a monadic democratic
peace (Gartzke & Weisiger, 2013: 172) and the
observation of an ‘autocratic peace’ (Werner, 2000;
Peceny, Beer & Sanchez-Terry, 2002) support this argu-
ment.17
An autocratic peace can hardly be explained by
constraints inherent in autocratic regimes, but must be
due to shared interests.
Gartzke (1998, 2000) shows that controlling for joint
interests weakens the magnitude and significance of the
evidence for a democratic peace.18
Joint interests and
joint regime types may be linked through three pathways.
First, joint democracy may itself give rise to joint
interests, such as an interest in the promotion of democratic
regimes or through similar incentives for political
leaders to expand the territory they control. The profitability
of occupation is less certain for democratic leaders
than for autocratic countries, since the benefits of occupation
have to be shared between almost as many as
those who bear the costs (Rosecrance, 1986). Moreover,
in order to extract much from the conquered territory,
the people resident there have to be denied the political
rights that are held by the citizens of the occupying coun-
try.19
Hence, joint democracy may lead to the mutual
acceptance of international borders, removing an important
source of war (Huth & Allee, 2002). Relatedly,
Schweller (1992) argues that regime type affects how
declining powers behave. When challenged by rising
powers, realist theory posits that leading powers wage
preventive wars to maintain their military hegemony.
Preventive wars are less attractive to democratic leaders.
If the rising power is another democracy, the historical
absence of war between democracies indicates that the
threat is minimal. If it is non-democratic, the public is
wary of the risks and costs of a war where the danger is
not imminent, and the formation of alliances to counterbalance
the non-democratic threat is often a preferable
strategy.20
Internal conflict
The earliest arguments for an internal democratic peace
are related to the normative and structural explanations
of the interstate variant. Democracy is seen as a system
for peaceful resolution of conflicts, as conflicting claims
by rival social groups are solved by majority votes or consensual
agreements. If individuals are denied the political
rights and the economic benefits they believe they are
entitled to, they may react with aggression and organize
violent political opposition. If conflict results from ‘relative
deprivation’ (Davies, 1962; Gurr, 1968), democracies
should be more peaceful internally than other
regime types. Armed rebellion will not be profitable since
democracies both allow discontent to be expressed and
have mechanisms to handle it.
Another argument holds that democratic institutions
alter the risk of internal conflicts by facilitating effective
bargaining and reducing commitment problems.
14
But see the debate in Security Studies 21(3) following Trachtenberg’s
article.
15
This proposition is contested, however. See Brown et al. (2011) for
a collection of essays on democracies and war victory.
16
Gowa (2011: 169) maintains that ‘dispute and war rates by dyad
type converge after the collapse of the bipolar system’ using much
more recent data. This conclusion is contested by Park (2013),
however.
17
Raknerud & Hegre (1997), however, demonstrate that the
‘autocratic peace’ to a large extent is due to the tendency for
democracies to ally with each other in large multi-actor wars.
18
Note that Oneal & Russett (1999) question how much the
democratic peace is due to joint interests.
19
Such dual standards certainly exist, but they often imply some
normative costs related to the occupation.
20
See Levy (2008) for an extensive review of this argument.
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Acemoglu & Robinson (2006: 24–25) note that citizens
are excluded from de jure power in a nondemocracy.
Still, they always enjoy some de facto power
that sometimes allows citizens to obtain policy concessions
from the elites in the short run. It is uncertain
whether these will be maintained, however, since the
balance between various social groups is transitory. Citizens,
then, should demand that today’s de facto power
is translated into de jure power that secures long-term
concessions. This demand may be backed by a threat
of revolution – a civil war. The elites cannot credibly
commit to a promise of policy concessions in the indefinite
future, however, as long as de facto power is transitory.
Democratic institutions are the solution to this
commitment problem (Acemoglu & Robinson,
2006). This explains democratization and shows why
democratic institutions reduce the risk of (revolutionary)
civil wars. Fearon (1995) likewise argues that bargaining
failures and commitment problems are
important explanations of war, and Fearon (2004:
288) argues that democratic regimes facilitate bargaining
and credible commitments for internal conflicts.21
If either of these accounts is true, fully fledged democracies
are less conflict-prone than repressive autocracies.
One possible reason for not observing this is that democracies
often are faced with opportunistic rebels whose
aims do not reflect the interests of broad social groups.
For internal conflicts, a parallel to the mobilization argument
formulated for interstate conflict would encounter
difficulties. Both democracies and non-democracies use
military force to counter illegitimate armed opposition,
but autocracies may make much more extensive use of
repression without losing legitimacy – using violence
to silence opponents, censorship, arbitrary imprisonment
without trial, etc. Autocracies may indiscriminately
target entire population groups to coerce influential individuals
(Davenport & Armstrong, 2004; Carey, 2010).22
Autocracies also buy off other parts of the opposition by
granting ministerial posts and by the selective channeling
of public funds (Fjelde & de Soysa, 2009). The combination
of these two methods allows effective divide-andrule
strategies. Autocracies also repress the formation of
organizations before they can reach the stage of armed
insurgencies. Hence, regimes that feature both democratic
and autocratic characteristics are partly open yet
lack effective means of solving conflicts. In such political
systems, repression is difficult since some organization of
opposition groups and some opposition expression of
discontent are allowed, but mechanisms to act on the
expressed discontent are incomplete (cf. Davies, 1962;
Boswell & Dixon, 1990; Muller & Weede, 1990; Hegre
et al., 2001). Hence, repression is ineffective if ‘grievance’
is not simultaneously being addressed, which is
why we observe an inverted-U relationship between
democracy and peace.
All in all, precisely because of the constraints on indiscriminate
use of force, democracies may be disadvantaged
when faced by opportunistic rebel groups. This claim has
recently been contested, however. Analyzing data for
insurgencies over the 1800–2006 period, Lyall (2010)
finds no evidence that democracies are more frequently
defeated or have to sustain conflict for longer periods.
Does democracy cause peace?
Empirically, the correlation between democracy and
interstate peace is well established, as is the correlation
between consolidated democracies and absence of internal
conflict. Still, this does not necessarily mean that
democracy causes peace. Two main objections have been
raised to that causal inference – peace may cause democracy,
or some other societal factors may cause both
democracy and peace. Since these counter-arguments
largely focus on what explains democratic institutions
at the country level, the arguments apply to the domestic
as well as the interstate democratic peace.
Putting the cart before the horse?
An implicit assumption in many statistical studies of
the democratic peace is that the causal arrow goes from
democracy to peace. Although not dismissing the pacifying
effect of democracy completely, Thompson
(1996) and Rasler & Thompson (2004) show that geopolitical
constraints that were in place before democratization
can account for the subsequent peace. Layne
(1994: 45) argues that democratic regimes can afford
democratic systems, ‘because there is no imminent
external threat that necessitates a powerful governmental
apparatus to mobilize resources for national security
purposes’. Boix (2011) shows that democratization has
been more frequent during periods where democracies
have been hegemonic powers. Gates, Knutsen & Moses
(1996: 5) add that peace leads to trade, investment, and
economic growth, and thereby to democratization.
Indeed, the idea of a reverse causation goes at least back
to Wright (1965/1942: 841).
21
These views of democratic institutions as commitment devices are
related to the signaling explanation for the interstate democratic
peace.
22
Also see Davenport (2007b).
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Mousseau & Shi (1999) discuss the temporal aspects
of the issue, and conclude that there is little evidence that
autocratization tends to occur during or after wars – in
fact, the opposite may be the case when democracies win
the wars (Mitchell, Gates & Hegre, 1999). The main
threat to the democratic peace proposition is change
toward autocracy in anticipation of war. By means
of interrupted time-series analysis, Mousseau & Shi
(1999) find no clear trend of states changing toward
autocracy before wars. Using instrument-variable methods,
Kim & Rousseau (2013) agree that the democracy–peace
correlation holds even when accounting for
the pre-existing amount of violence in a region. Reiter
(2001) finds that international conflict rarely blocks
transitions to democracy. The simultaneous-equation
analysis in Reuveny & Li (2003) shows that conflict
reduces democracy, but also that democracy reduces
conflict.23
In all, most attempts to ascertain the direction
of causality by means of appropriately designed statistical
methods seem to support the core tenet of the democratic
peace, although there are dissenting voices such
as James, Solberg & Wolfson (1999).
Gibler (2007) formulates a more specific reversecausation
argument. He points to Boix (2003) who notes
the importance of the settlements of territorial claims in
17th- and 18th-century Europe. Without these, the fundamental
economic changes required for democratization
would not have happened.24
Such territorial
agreements, then, indirectly give rise to clusters of
democracies that have joint interests in keeping a separate
peace. The empirical analysis in Gibler (2007) indicates
that exogenous predictors of border stability tend to
decrease the likelihood of territorial disputes and increase
the probability of joint democracy, and that the evidence
for the democratic peace is weaker when predictors of border
stability are controlled for. The conclusions remain in
doubt, however, as Park & Colaresi (forthcoming) report
inability to replicate the results. Gibler & Tir (2010)
expand the notion of territorial settlements to one of ‘positive
territorial peace’, and show that peaceful territorial
transfers lead to democratization and lower levels of
militarization.
The issue of reverse causation has not been equally
prominent in the study of democracy and internal
conflict, with some notable exceptions in particular in
studies of repression and violence (Carey, 2006; Moore,
1998). The relative-deprivation argument, however,
implies reverse causation. If deprivation is due to the lack
of political rights, and civil war is a useful strategy to
obtain such rights, war should lead to democracy. In
contrast to this expectation, however, Gleditsch & Ward
(2006) do find that civil wars tend to undermine democracies
but do not affect the durability of autocracies.
What drives democratization and peace?
Perhaps the most serious challenge to the democratic
peace comes from arguments suggesting that both
democracy and peace are outcomes of more fundamental
societal changes. Most of these are associated with socioeconomic
development.
Institutional consolidation. A possible indication of
this is that the interstate democratic peace is weaker for
young democracies (Maoz & Russett, 1992). Indeed, the
process of democratization may increase the risk of war
in the short run (Mansfield & Snyder, 1995).25
Relatedly,
changes in the political institutions of a country are
likely to be accompanied by a heightened risk of civil war
(cf. Snyder, 2000; Hegre et al., 2001; Fearon & Laitin,
2003; Cederman, Hug & Krebs, 2010). Firstly, changes
in a democratic direction are likely to be accompanied by
reduced repression, allowing communal groups to mobilize.
In addition, it takes a long time to make new institutions
sufficiently efficient to accommodate deep social
conflicts. Groups that increase their political influence
will raise their expectations of real improvements in their
living conditions, but these can be slow to materialize.
Losers from the institutional changes, then, have an
incentive to incite armed insurgencies to re-establish the
previous status quo.
Fearon & Laitin (2003: 85) interpret the inverted-U
finding for internal conflicts as due not to the institutional
characteristics themselves, but to an underlying
conflict over the setup of the system: ‘‘‘anocracies’’ are
weak regimes, lacking the resources to be successful autocrats
or containing an unstable mix of political forces that
makes them unable to move to crush nascent rebel
groups’. This interpretation is supported by Gleditsch &
Ruggeri (2010). Their proxy of instability (a variable
recording recent irregular transitions of power) is associated
with a high risk of conflict onset. Moreover, when
23
The analysis in Reuveny & Li (2003) is hard to interpret, however,
since they attempt to model the effect of conflict on the democracy
level of both states in the dyad, using a weak-link design that seems
partly inappropriate.
24
Boix (2003: 228) notes, however, that territorial settlements are
not the only explanation of the European ‘growth miracle’.
25
See, however, the critiques of Mansfield & Snyder in Ward &
Gleditsch (1998), Narang & Nelson (2009), and Bogaards (2010).
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controlling for it, they find a monotonic negative relationship
between democracy and risk of conflict.
Elections provide a special case of change – not to
the institutions, but to the de jure distribution of
power within electoral regimes. In new democracies,
there is considerable uncertainty whether the main
actors are truly committed to respecting the outcomes
of elections. Most actors prefer to secure power by
means of electoral victory since it bolsters the legitimacy
of their rule. If they lose, however, they may
find an attempt to seize power by force preferable
to accepting the defeat. Several studies confirm that
elections tend to be followed by an increased risk of
internal conflict (Collier, Hoeffler & So¨derbom, 2008)
or ethnic conflict (Cederman, Gleditsch & Hug, 2013).
Market norms. Mousseau (2000) argued that both
democratic consolidation and the democratic peace are
due to a specific set of norms of contracting. These
norms emerge in economically developed countries by
a ‘process of cultural materialism’. Economic development
requires a complex division of labor which typically
is achieved through a dense web of voluntary
contracts. These contracts pave the way for democratization
since they foster norms of negotiation, trust,
equity between contractees, and respect for property
rights. The international manifestation of such norms
is more peaceful behavior, since wars of conquest would
violate these norms. An implication of this argument is
that only developed democracies can maintain a separate
peace. This expectation is supported in a set of statistical
studies of interstate conflict (Mousseau, 2000; Mousseau,
Hegre & Oneal, 2003; Hegre, 2000) and internal conflict
(Hegre, 2003; Collier & Rohner, 2008).
Controlling for a more direct measure of ‘contractintensive
economies’ (CIE), Mousseau (2009: 82) concludes
that ‘democracy is not a likely cause of peace
among nations’. Dafoe, Oneal & Russett (2013), however,
reject this conclusion. Still, they do find support for
the effect of CIEs controlling for joint democracy and
acknowledge that there is some overlap between the democratic
peace and the effect of CIEs (Dafoe, Oneal &
Russett, 2013: 209).26
Lootability. Another aspect of economic development is
that it favors non-lootable or non-appropriable assets
over lootable assets – ‘commerce’ is gradually replacing
‘conquest’ since ‘labor, capital, and information are
mobile and cannot be definitively seized’ (Rosecrance,
1986: 48).
This development-related change has an analogy in
internal conflicts. When land-based assets such as most
primary commodities are economically dominant,
states have strong incentives to use physical force to
retain control, and potential insurgents have similar
incentives to try to seize control over the central power
or to obtain larger autonomy for a region. This argument
reflects the importance placed on primary commodity
exports by Collier & Hoeffler (2004) and
Fearon & Laitin (2003). Several rebel economic activities
require high rebel territorial control, such as taxation
of natural resource production, rich landowners,
or household incomes (Fearon & Laitin, 2003). In the
words of Boix (2008: 432), ‘In economies where wealth
is either mobile or hard to tax or confiscate, sustained
political violence to grab those assets does not pay off
since their owners can either leave in response to the
threat of confiscation or are indispensable to the optimal
exploitation of assets.’ Boix finds strong empirical
evidence for this account. It is supported by numerous
empirical studies that show that extensive reliance on
the export of oil – a highly appropriable asset – is associated
with conflict as well as authoritarian rule (Fearon &
Laitin, 2003; Fjelde, 2009; Ross, 2001). Relatedly,
the models of democratization in Boix (2003) and
Acemoglu & Robinson (2006) provide an explicit link
between democratization and civil war – elites agree to
democratization because they fear a revolution staged by
the poor. Democratization, they argue, is least likely when
inequality is extensive, since the redistributive tax rate preferred
by the median voter then will be very high. Revolutions,
then, will be more frequent in unequal societies,
since the elites have a stronger incentive to resist
democratization.
If the assets that the rich control are in the form of
land or other resources that cannot be moved out of the
country, the poor will be able to impose radical taxes if
they get to control the tax rate (Boix, 2003). If most of
the wealth is in the form of financial capital, a larger
fraction of it is ‘safe’ from taxation, and democratization
is less threatening. Moreover, where lootable assets
are predominant, rebel groups have incentives to stage
limited campaigns not to entirely take over the government,
but to secure local access to profitable natural
resources.
26
Dafoe, Oneal & Russett (2013) show that Mousseau’s main
inference hinges on an erroneous interpretation of the interaction
term between democracy and CIE – in their replication, joint
democracy retains considerable explanatory power even when
controlling for the CIE term. They also question the quality of the
proxy variable for CIEs used by Mousseau (2009).
Hegre 7
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Joint interests. The democratic peace seen as merely
‘joint interests’ (Gartzke, 1998) may also be a function
of economic development, as noted in Rosecrance
(1986) and Gartzke (2007). Well into the 20th century,
an ‘obsession with land’ was the major cause of war since
states could improve their position by seizing other
nations’ territory (Rosecrance, 1986: 48). During the
20th century, however, mobile factors of production –
capital and labor – surpassed land in importance for productive
strength. At the same time, nationalist resistance
to occupation became more frequent, increasing the cost
of extracting resources from a territory (also see Boix,
2003: 44–45). In addition, the diversity of resources
employed speaks against a military strategy (Rosecrance,
1986; Brooks, 1999). Development may provide the
motive and means for a state to seize a particular territory
from another by force, but it also increases its dependence
on third parties. War hampers trade with third
parties either because of political reactions or because the
heightened risk resulting from conflict increases the price
of traded goods. The constraints imposed on developed
states through their extensive trade with a great number
of other nations are apt to outweigh the prospect of gaining
control over one particular territory.27
Developed societies that are economically reliant on
the revenues from international trade and investment
place much more emphasis on the protection of property,
political stability, and the integrity of international
borders than on expanding own territories. Developed
societies, then, have a joint interest in restricting
attempts to expand territories, such as Saddam Hussein’s
conquest of Kuwait, and a lack of interest in contesting
own borders. Similar joint-interest explanations also
apply to internal conflicts and to the incentives to resist
democratization. Economic development, in particular
the reliance on relations with international markets, also
means that a large set of actors become reliant on preserving
political stability.
Interdependence. In several theories of democratization
(Dahl, 1971; Olson, 1993; Boix, 2003), the high costs of
violence and repression in densely interacting societies is
an important factor. Dahl (1971) sees ‘modern dynamic
pluralist’ societies as an essential prerequisite for democracy
– democracy prevails because citizens can credibly
threaten to hurt the elites economically by means of
strikes, protests or exiting the country. The diversification
and division of labor in developed economies leads
to both democracy and internal peace.
For interstate conflict, a similar argument states that
strong dependence on trade and on capital constrains
belligerent actors (Angell, 1910; Russett & Oneal,
2001). Domestic and foreign capital is likely to flee the
country if war breaks out. Less capital-intensive economies
are less constrained by these considerations
(Gartzke, Li & Boehmer, 2001). In a critical review of
the democratic peace, Gat (2005, 2006: 658) argues that
it has overlooked the industrial revolution: ‘Rather than
the cost of war becoming prohibitive . . . it was mainly
the benefits of peace that increased dramatically once the
Malthusian trap was broken, tilting the overall balance
between war and peace for . . . industrializing and industrial
societies, regardless of their regime, for which wealth
acquisition ceased to be a zero-sum game.’
The capitalist peace. Gartzke (2007) argues that the liberal
peace really is a ‘capitalist peace’. The rhetoric value
of this term is greater than its precision. In effect,
Gartzke’s argument draws on several of the effects of
socio-economic development reviewed above. Interdependence
and mobility of assets are equally important
as the particular economic freedoms and financial structures
traditionally associated with ‘capitalism’. Echoing
Rosecrance, Gartzke (2007: 172) argues that development
‘leads states to prefer trade to theft’, but does not
weaken their resolve to defend their borders. At the same
time, developed states are typically militarily powerful
and are able to wage wars over long distances. Since
many wars are fought over non-territorial issues (e.g. to
defend a particular political system in another state, or
to prevent the development of nuclear capabilities),
developed states are willing to fight long-distance wars
where conquest is not the motivation. This leads Gartzke
to expect that development leads contiguous dyads to be
less likely to experience militarized interstate disputes
and non-contiguous dyads to be more likely to do so.
He finds support for both these hypotheses, and finds
that the terms representing the democratic peace are
non-significant when controlling for the ‘capitalist’ factors.
Gartzke & Hewitt (2010) obtain similar results for
international crises.
The capitalist peace challenge to the democratic peace
is taken up by Dafoe (2011) and Choi (2011), who show
that the democratic peace retains support in the model of
Gartzke (2007) with some specification changes that
most analysts would agree are improvements to the original.
The complete replication results presented in Choi
27
Supportive of this view, Hegre (2000) and Mousseau, Hegre &
Oneal (2003) indicate that the pacifying impact of trade is
conditional on the level of development.
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(2011) show, however, that the substantial effect of the
democratic peace is weaker when controlling for ‘capitalist’
factors than without, and Gartzke’s main hypotheses
retain support in their replications.
Any residual effects of democracy?
The arguments reviewed here may imply that socioeconomic
development is an important pre-condition for
the democratic peace, in the context of both interstate
and internal conflicts. It would be premature to conclude
that development completely removes the importance of
democratic institutions, however. First, if the economic
underpinnings for democracy were sufficient for citizens’
welfare, we would not have seen the systematic trend of
transitions toward democracy when states become economically
more developed (Przeworski et al., 2000;
Boix, 2003, 2011). Because of commitment problems,
the ‘invisible hand’ of the market is insufficient to prevent
conflict. Both elites and citizens see the need to
design institutions that formalize access to decisionmaking
power and also bind both sides to this formalization
should the underlying balance of power change at some
point in the future.
One might also argue that development presupposes
some kernels of democratization. For instance, the emergence
of market norms crucially depends on the protection
of property. Effective autocratic governments can
protect property against ‘roving bandits’, but have a harder
time assuring market actors that they will resist the temptation
to confiscate the property of citizens. This, according
to Olson (1993: 572), can only happen when rulers
have very long time horizons, and long time horizons are
credible only in democratic systems: ‘History provides not
even a single example of a long and uninterrupted
sequence of absolute rulers who continuously respected
the property and contract-enforcement rights of their subjects.’
Indeed, Olson (1993: 574) claims that ‘Individual
rights to property and contract enforcement were probably
more secure in Britain after 1689 than anywhere else,
and it was in Britain, not very long after the Glorious Revolution,
that the Industrial Revolution began.’ If so,
democracy is causally prior to development. At least, it
is likely that democracy and economic modernization
have developed in a dialectic process not unlike the Kantian
learning process discussed in Cederman (2001). This
process is probably related to a general shift in norms
against the use of violence. Several of the long-range processes
discussed in Gat (2006) and Pinker (2011) may be
seen as informing explanations of democratization as
much as explanations for the decline of war.
Moreover, democracy and development may require
each other to produce socially optimal outcomes.
Mousseau (2000) and Mousseau, Hegre & Oneal (2003)
find that the effect of democracy is contingent on development.
Dafoe, Oneal & Russett (2013: 206) acknowledge
that democracy and development might mutually
reinforce each other: ‘Economic norms may express
themselves more forcefully in liberal polities; moral concerns
weigh more heavily when people are rich; the stability
and bargaining credibility made possible by
democracy . . . is more robust when governments are
dependent on capital.’ Moreover, development in general
strengthens and stabilizes democratic institutions
(Przeworski et al., 2000; Gates et al., 2006),28
and developed
democracies should therefore be better able to constrain
leaders and affect their audience costs and
incentives to avoid failed wars.
Inthecaseofdomesticconflict,Hegre(2003),Collier&
Rohner (2008), and Gleditsch, Hegre & Strand (2009)
also find democracy to reduce the risk of internal conflict
more effectively in high-income countries. This may be
because the democratic strategies for maintaining order
may be more costly than the autocratic strategies. Identifying
and prosecuting individuals within groups that
make use of illegal means of protest takes more resources
than indiscriminate repression of the entire group. To
maintain a democratic civil peace, the government must
be capable of not only actively affecting the societal distribution
of resources but also preventing abuses of one
social group by another. Most democracy datasets measure
the extent to which governments are accountable
and constrained, but rarely capture their capabilities to
implement their decisions. Hegre & Nygård (forthcoming)
indicate that such capabilities are just as important
as the de jure institutions. Relatedly, political systems
that combine democratic and autocratic features, for
instance, may be regarded as having low capability
because of their lack of consistency (Gates et al., 2006;
Gleditsch & Ruggeri, 2010). Kalyvas & Balcells
(2010), moreover, show that after the end of the Cold
War, an increasing proportion of internal conflicts have
been ‘symmetric non-conventional’ where both the government
and the rebels lack the capacity to fight regular
wars. This trend coincides with an increased number of
low-income, low-capacity democracies, in particular in
sub-Saharan Africa.
Development also affects the policy incentives for
democratically elected leaders. Illiterate populations are
28
However, see Boix & Stokes (2003).
Hegre 9
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often unable to make use of the democratic institutions
to constrain the elected leaders. Elected offices are
extremely valuable to their incumbents in societies with
immobile assets and extensive inequality (Boix, 2008),
widespread corruption, and few alternative economic
opportunities, inducing incumbents to concentrate on
retaining power rather than serving the electorate. In
sum, leaders in low-income democracies may be both
less able and less willing to address social conflicts that
underlie ‘relative-deprivation’ mechanisms.
Development does not have the same effect in nondemocratic
systems. Hegre (2003) indicates that violent
conflict becomes more frequent in authoritarian states
as they modernize. This is in conflict with the empirical
implications of the ‘opportunity’ (Collier & Hoeffler,
2004) or ‘feasibility’ accounts of conflict (Collier,
Hoeffler & Rohner, 2009). Development, to the extent
it fosters ‘modern dynamic pluralist’ societies, may tend
to shift the balance in favor of ‘justice-seeking’ rather
than ‘loot-seeking’ motivations for internal conflicts,
since the education, urbanization, and economic leverage
associated with development raise the political expectations
of citizens and help them resolve their collective
action problems. It is clear that demands for democratization
tend to intensify with higher education levels and the
increased dispersion of economic leverage in modern
economies. As exemplified by the recent conflicts in Libya
and Syria, elites that resist these demands run a risk of
escalating such conflict to civil war. Economic development
may be a necessary condition for the democratic
peace, but not a sufficient one.
On the other hand, the autocratic means to maintain
order do not become more effective with increasing
development. First, widespread repression is more likely
to meet widespread popular resentment the more educated
the population is. With more human and social
capital at hand, citizens are better able to force a repressive
government to change its behavior. Eventually, the
elites may be forced to open up the political system to
allow the formation of democratic political systems. This
transition process is often associated with civil conflict.
Conclusions
This review has discussed recent research on the relationship
between democracy and armed conflict, covering
both conflicts internal to countries and interstate conflicts.
Although there are many differences between the
interstate and domestic conflict, the review indicates
there are also several similarities. In particular, some
important challenges to the democratic peace apply to
both types of conflict. The most fundamental challenge,
in my view, is that there might be underlying social
changes that explain both the development of democratic
institutions and peaceful resolution of social
conflicts. These changes are typically summarized as
socio-economic development, and typically work through
the incentives for using physical force for political goals. At
the same time, as recently seen in Syria, relative economic
development in itself is not sufficient to prevent armed
conflict. Democratic institutions are formal codifications
of nonviolent conflict resolution procedures. Socioeconomic
development is likely to change societies such
that nonviolent conflict resolution is an underlying
pareto-optimal equilibrium, allowing actors to agree to
such codifications. In the absence of formal codifications,
however, actors may be unwilling to trust that this underlying
equilibrium exists. Hence, democratic institutions
may be necessary to allow the beneficial changes due to
development to be manifested as more peaceful societies.
The review suggests several avenues for future research.
First, there is no consensus on the relative importance of
multiple explanations of the empirical observations.
A recurrent challenge is to identify empirical implications
that allow distinguishing clearly between them. This
requires new data – democratic peace research tends to
rely excessively on a very limited number of datasets. This
is particularly true for the measure of democracy, where
most studies use the Polity dataset (Jaggers & Gurr,
1995; Marshall, Gurr & Jaggers, 2013). Disaggregating
the institutions along the lines of Carey (2007) and
Fjelde (2010) will be helpful, as well as making use of
new datasets measuring various aspects of democratic
institutions (e.g. Boix, Miller & Rosato, 2013; Regan,
Frank & Clark, 2009; Coppedge et al., 2011).
Another avenue to explore is the dynamics between
socio-economic changes, institutional changes, and the
incentives for the use of political violence posed by the
challenges reviewed above. There is much to learn from
how these factors relate to exogenous factors such as
changes in technology or in demographics (Dyson,
2012; Gat, 2005; Urdal, 2005), and how changes in one
of them affect the others.
Acknowledgements
Thanks to Halvard Buhaug, Nils Petter Gleditsch,
Idunn Kristiansen, Jack Levy, Naima Mouhleb, and
JPR’s reviewers for constructive comments to earlier versions
of the manuscript. The research was funded by the
Research Council of Norway, projects 217995/V10 and
204454/V10 (see http://havardhegre.net for details).
10 journal of PEACE RESEARCH
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HÅVARD HEGRE, b. 1964, Dr Philos in Political Science
(University of Oslo, 2004); Dag Hammarskjo¨ld Professor of
Peace and Conflict Research, Uppsala University (2013– );
Research Professor, Peace Research Institute Oslo (2005– );
current research interests: democracy, development, and
armed conflict; forecasting of armed conflict.
14 journal of PEACE RESEARCH
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