A neoclassical realist model of overconfidence and the Japan-Soviet Neutrality Pact in 1941

Why did Japan conclude the Japan-Soviet Neutrality Pact in 1941, even though it knew the German-Soviet relations were deteriorating and heading towards a disastrous war? Under the Tripartite Pact, it would be irrational for Japan to approach the USSR, which Germany had decided to invade. This article examines this long-standing puzzle in Japanese diplomatic history (also an anomaly of neorealism) by developing a new neoclassical realist model termed 'neoclassical realist model of overconfidence' based on self-deception in evolutionary psychology using scientific realism in the philosophy of science as a metatheoretical foundation. Drawing on neoclassical realism, I argue that Japan's balancing strategy during 1940-41, which initially reflected the tripolar structure of the international system (independent variable), ultimately resulted in the suboptimal balancing of the Japan-Soviet Neutrality Pact (dependent variable) due to Yosuke Matsuoka's (Japanese foreign minister) self-deception, including the positive illusion and cognitive dissonance effect (intervening variable).

Automated summary

This article examines the reasons behind Japan's decision to sign the Japan-Soviet Neutrality Pact in 1941, despite the deteriorating German-Soviet relations. It argues that Japan's balancing strategy and the self-deception of its foreign minister, Yosuke Matsuoka, played a crucial role in this decision.