Exit Rights, Free Movement Alliances, and Game-Theoretic War Deterrence

Abstract (English) This paper models war deterrence through guaranteed exit rights as a three-stage extensive-form game. In Stage 1, states form a free movement alliance; in Stage 2, a potential aggressor chooses between war and peace; in Stage 3, citizens make endogenous emigration decisions. The subgame-perfect Nash equilibrium (SPNE) shows that anticipated brain drain drives the war incentive below zero when exit freedom exceeds a threshold value. The emigration rate arises endogenously from a concave production function; the main result holds a fortiori for any elasticity of substitution σ ≤ 1. The model identifies precise scope conditions and is confronted with four counterexamples (GDR 1961, North Korea, Syria, Ukraine 2022), one post-hoc illustration (Russia 2022), and one confirmatory case (GDR 1989). Zusammenfassung (Deutsch) Dieses Papier modelliert Kriegsabschreckung durch garantierte Ausreiserechte als dreistufiges extensives Spiel. In Stufe 1 bilden Staaten eine Free Movement Alliance, in Stufe 2 wählt ein potenzieller Aggressor zwischen Krieg und Frieden, in Stufe 3 treffen Bürger endogene Emigrationsentscheidungen. Das teilspielperfekte Nash-Gleichgewicht (SPNE) zeigt: Antizipierter Brain Drain drückt den Kriegsanreiz unter null, wenn Ausreisefreiheit einen Schwellenwert übersteigt. Die Emigrationsrate ergibt sich endogen aus einer konkaven Produktionsfunktion; das Hauptergebnis gilt a fortiori für jede Substitutionselastizität σ ≤ 1. Das Modell identifiziert präzise Scope Conditions und wird mit vier Gegenbeispielen (DDR 1961, Nordkorea, Syrien, Ukraine 2022), einer Post-hoc-Illustration (Russland 2022) und einem Bestätigungsfall (DDR 1989) konfrontiert. This is an advanced draft. The paper has undergone multiple internal review cycles and is prepared for Journal of Theoretical Politics submission; further journal-driven revisions remain possible. Changes in Version v7 (April 2026; prepared) Prepared after the JTP-focused 7-phase review and the 2026-04-30 live Zenodo health check. The live Zenodo latest version is v6 / record 19073281; this metadata file prepares the next new-version upload on that record. Critical: Article 2 replaces the previous live Article 3 file set as the JTP submission candidate. Critical: CES robustness formalized as Lemma A.1; SPNE wording narrowed to the unique peace outcome where appropriate. Major: Selectorate and capitalist-peace discussion strengthened, including DPT/Capitalist Peace differentiation and H2 prediction. Major: GDR 1989 added as an analogous intrastate brain-drain mechanism; abstract and case framing synchronized. Major: Bibliography verified against original publications; EN and DE versions migrated to the shared BibTeX file. DE/EN: German Article 2 synchronized with the English JTP candidate, including CES appendix and §7.1 additions.