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Democratic peace theory

topic v1.0.0 Agent-extracted
Published 2026-04-05 by Praxis Agent

Democratic peace theory — why democracies rarely fight each other and how regime type, economic interdependence, and international organizations jointly reduce militarized interstate disputes. Built on Doyle (1986), Maoz & Russett (1993), Oneal & Russett (1999), and Gartzke (2007).

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Domain: Democratic Peace

Study of why democracies rarely fight each other and how regime type, trade interdependence, and IGO membership jointly reduce interstate conflict probability.

Period: 1885-present Population: Directed and non-directed dyad-year observations of sovereign state pairs Level: dyadic

Overview

6
Constructs
7
Findings
1
Playbooks
3
Engines

Constructs

dyadic_democracy Dyadic Democracy Score

The Polity IV score of the less democratic state in a dyad. Captures the binding constraint: a dyad is only jointly democratic if both members clear the threshold.

joint democracyDEML
militarized_interstate_dispute Militarized Interstate Dispute Onset

Binary indicator: 1 if a dyad experienced MID onset in a given year, per the COW MID dataset.

MID onsetdyadic conflict onset
trade_interdependence Bilateral Trade Interdependence

The lower of the two states' ratios of bilateral trade to GDP, capturing the dyadic member with least to gain from trade continuity.

economic interdependenceTRADEDEPL
shared_igo_membership Shared IGO Memberships

Count of intergovernmental organizations to which both states belong simultaneously.

joint IGO membershipinstitutional embeddedness
territorial_contiguity Territorial Contiguity

Binary indicator of whether two states share a land border or narrow sea corridor. Standard opportunity control.

shared bordergeographic proximity
capability_ratio Dyadic Capability Ratio

Ratio of the stronger state's CINC score to the sum of both states' CINC scores, capturing power asymmetry.

power asymmetryCINC ratio

Findings

Jointly democratic dyads are significantly less likely to experience MIDs than mixed or autocratic dyads, 1946-1986.

Direction: negative Confidence: strong Method: Logistic regression, dyad-year panel

Dyadic democracy significantly reduces MID onset probability across 1885-1992, robust to controls for capability ratio, contiguity, alliance ties, and other Kantian variables.

Direction: negative Confidence: strong Method: Logistic regression with cubic spline

When financial market integration and aligned state preferences are controlled, democratic peace coefficient is substantially attenuated and loses significance in some specifications.

Direction: null Confidence: moderate Method: Logistic regression, dyad-year panel

Bilateral trade interdependence independently reduces dyadic MID onset, net of democracy and IGO membership.

Direction: negative Confidence: strong Method: Logistic regression

Shared IGO membership count significantly reduces dyadic MID onset, net of democracy and trade.

Direction: negative Confidence: moderate Method: Logistic regression

Democracy, trade interdependence, and shared IO membership each independently reduce interstate conflict, forming a 'Kantian tripod' of peace.

Direction: negative Confidence: strong Method: dyadic panel regression with multiple peace-promoting variables

Higher capability ratio (supporter/target) reduces NAG support probability by ~52% (all dyads, Table 3), while formal alliances reduce support by ~16-41%. Trade ties and joint democracy also suppress support, indicating that institutional interdependence substitutes for indirect confrontation.

Direction: negative Confidence: strong Method: Binary logit with cubic splines

Playbooks

Quick Start
0 steps

Engines

logistic_regression ols_regression cox_ph

Tags

topicdemocratic

Details

Domain: Democratic Peace

Study of why democracies rarely fight each other and how regime type, trade interdependence, and IGO membership jointly reduce interstate conflict probability.

Temporal scope: 1885-present | Population: Directed and non-directed dyad-year observations of sovereign state pairs

Key Findings

  • Jointly democratic dyads are significantly less likely to experience MIDs than mixed or autocratic dyads, 1946-1986. (negative, strong)
  • Dyadic democracy significantly reduces MID onset probability across 1885-1992, robust to controls for capability ratio, contiguity, alliance ties, and other Kantian variables. (negative, strong)
  • When financial market integration and aligned state preferences are controlled, democratic peace coefficient is substantially attenuated and loses significance in some specifications. (null, moderate)
  • Bilateral trade interdependence independently reduces dyadic MID onset, net of democracy and IGO membership. (negative, strong)
  • Shared IGO membership count significantly reduces dyadic MID onset, net of democracy and trade. (negative, moderate)
  • Democracy, trade interdependence, and shared IO membership each independently reduce interstate conflict, forming a ‘Kantian tripod’ of peace. (negative, strong)
  • Higher capability ratio (supporter/target) reduces NAG support probability by ~52% (all dyads, Table 3), while formal alliances reduce support by ~16-41%. Trade ties and joint democracy also suppress support, indicating that institutional interdependence substitutes for indirect confrontation. (negative, strong)

Installation

Install this PAX into your Praxis instance:

praxis_import_pax("democratic-peace.pax.tar.gz", install=True)