聯盟理論之研究：現實主義的觀點

On the Theories of Alliances: A Realist's Perspective

現實主義是過去50年，國際關係理論中面臨最多挑戰的理論，幾乎所有後起的重要國際關係理論，皆是以現實主義作為主要批判和打擊的對象。而現實主義本身也在歷次的國際關係理論典範的辯論中，有所調整與成長。因此，本文即欲透過現實主義內部各學者的觀點，分別針對：聯盟的成因、盟約的必要性、不對稱聯盟、聯盟瓦解的原因等四類問題領域來瞭解其對於聯盟理論研究的概況。現實主義學者起先是從「權力平衡」的觀點來解釋聯盟的形成，後來提出了「威脅平衡」的說法，認為國家在面臨威脅時，通常會採取制衡的手段。其他學者則提出「利益平衡」的觀點，說明國家往往是考量利害關係後選擇了依附來獲取和確保利益。更有學者反駁指出，國家在面臨威脅時，往往會推卸責任而非制衡。綜觀現實主義學者研究的成果可以發現，一、型塑聯盟最主要的成因是面臨共同威脅的國家彼此加強安全合作，但追求共同的利益、意識型態連結、外交經濟援助、政治滲透等也能成為聯盟關係建立的輔助或獨立因素，惟效果較不明顯。二、國家實力的大小與國際體系的極數對於國家選擇聯盟對象與政策產生影響與限制，應分別探討以進一步釐清彼此間的差異。三、現實主義本身的邏輯觀點即能解釋後冷戰時期美國主導的軍事聯盟持續發展之現象。聯盟理論僅強調聯盟會在威脅消失後逐漸瓦解，但並未限定此威脅必須以國家型態出現。

For five decades, Realism has been the most controversial one among theories of International Relations; just about all major IR theories that followed have their criticism centered on it. Realism itself has undergone changes and developments during the various debates of IR theory paradigm. Hence, this article intends to understand, through a realist's perspective, the causes of alliance formation, necessity for treaties of alliance, asymmetrical alliances, and reasons of alliance dissolution. Realists started off initially from the ''Balance of Power'' perspective to explain alliance formation, later they moved on to the ''Balance of Threat,'' suggesting that nations form alliances when faced by threats. Other scholars introduced the ''Balance of Interest'' perspective, arguing that nations normally prefer to bandwagon so as to ensure interests and gain benefits after careful considerations. There are even scholars who refuted the idea of balance, and indicated that nations tend to evade responsibilities in the face of threats. After a comprehensive review of the works by realist scholars, one can conclude the following findings: 1. the primary cause of alliance formation is the strengthening of security cooperation by nations that face common threat(s); while the pursuit of common interest(s), foreign economic aid, and political penetration may also be the supporting or independent factors of alliance formation, their effects are nonetheless of lesser significance. 2. Viable choices of alliance and alliance policies of a nation are affected and limited by its actual strength and the number of polarity within the international system, which should be discussed separately to shed light on the difference among these two. 3. The logical perspective of Realism itself can explain the phenomena of continuous development of the US-led military alliance in the post-Cold War era. The Alliance Theory emphasized merely the gradual dissolution of an alliance after the threats vanished, but never limited such threats to be posed by or in the form of a nation.