戰略模糊或清晰？戰爭議價理論與美國臺海兩岸政策的理性基礎

美國政府是否應該放棄長久以來「戰略模糊」而改採「戰略清晰」的臺海兩岸政策？自川普總統就任以來，美國實務界至今看法分歧。本文梳理此輪美國政府臺海兩岸政策辯論的爭點所在，並以戰爭議價理論的形式邏輯重新檢視美國兩岸政策採取戰略清晰的理性基礎。本文主張：定義為「在臺海兩岸爆發戰爭時，美國必定會與臺灣共同在軍事上反制中國」的戰略清晰在邏輯上缺乏理性基礎，難以維繫臺海的和平與穩定。本文透過對戰爭議價理論的邏輯演繹得知：在其他條件不變下，一旦美國政府的兩岸政策採取戰略清晰，美方不但將增添中國對臺灣發動預防性戰爭以武力追求事實統一的誘因，同時美方也將給予臺灣犯險挑戰中國政治底線而將美國捲入兩岸戰爭的誘因。其結果與《臺灣關係法》中預設要確保西太平洋和平、安全與穩定的美國政策目標自相矛盾。即便中國相對美國快速崛起的國際環境正在劇烈變遷，戰略模糊依舊是現階段美國政府避免中國與臺灣走向戰爭的最有效政策。

關鍵字

戰爭議價理論；兩岸關係；美國外交政策；戰略模糊；戰略清晰

並列摘要

Should the U.S. government abandon its longstanding policy of "strategic ambiguity" and replace it with "strategic clarity" toward the Taiwan Strait? Since the inauguration of President Donald J. Trump, the U.S. foreign policy community has had divergent perspectives. This essay provides a synthetical review of this debate and applies the bargaining theory of war to reexamine the rationalist foundation of the U.S. strategic clarity toward the Taiwan Strait formally. It argues that strategic clarity, defined as "the U.S. will certainly join Taiwan to counter China when a war occurs across the Taiwan Strait," cannot maintain peace and stability across the Strait due to the absence of a rationalist foundation. Deduced from the bargaining theory of war, this article shows that other things being equal, if the U.S.were to adopt a policy of strategic clarity, it would not only give China the incentive to wage a "preventive" war for de facto unification, but also give Taiwan the incentive to drag the U.S. into a war in the Taiwan Strait by violating China's "red lines." One way or another, this would jeopardize peace, security and stability in the Western Pacific and contradict the U.S. policy objectives stated in Taiwan Relations Act. Even if the rapid rise of China relative to the U.S. has dramatically altered the international environment, this paper argues that strategic ambiguity remains the most effective U.S. policy to prevent war in the Taiwan Strait.