自90 年代中期以來，學界對於恐怖主義的研究正日益深化，反恐措施也推陳出新。不過，恐怖主義攻擊卻未因此減少，反而從過去盛行的中東地區和發展中國家蔓延到威權的前蘇聯各國以及已開發國家。參與者也從過去的反殖民建國訴求者，擴大為宗教和其他激進運動的獻身者；手段上更普遍地採取自殺攻擊，而不在乎組織形象聲名狼藉和人員的損失。似乎強大的國家，其安全與反擊措施越嚴厲，越激發攻擊者的鬥志。這種「越挫越奮」的異常現象，對傳統的國關理論構成了不小的挑戰。 本文因此主張，除了持續傳統的安全和反恐研究，有必要導入近期西方若干新觀點來因應。其中之一即是有關「本體安全」概念的探索。「本體安全」主要涉及的是主體的自我認同，其「安全」受威脅的後果並不亞於實體、人身的「不安全」。英國前首相布萊爾因此把這個威脅描述成「觀念的戰役」。本文即藉由2005 年發生在英國本土的七七恐怖攻擊事件的初步論析，指出「本體安全」的恐怖主義研究未來具有的深厚潛力──它有助於在國際關係理論與安全研究實務上，帶來創新。但與此同時，本文認為，古今中外導致恐怖攻擊的因素甚多，「本體安全」雖提示了一個不宜忽略的研究面向，但亦需與其他既有觀點整合，始能增進其解釋力。

National security is traditionally comprehended in terms of the rationalist approach, of which the physical boundaries and the static “Self” of nation states are taken for granted. The concept of “security dilemma” is accordingly understood as the conflicting tendency between nations in the process of defense build-up. However, this article argues that another type of “security dilemma” should not be ignored: the more the units increase its physical capabilities, the less secure they are, due to the growing enthusiasm of the weaker to acquire from the situation. The author contends that the London terrorist bombing of 2005 was a good case to test the traditional concept of security. The home-grown terrorists were almost undetected by the UK security service. It is then argued that a new concept – ontological security may be helpful, by which the concern is moved from physical security to the stability of the “Self” of actors. In short, it is proposed that the alienated and humiliated “Self” of actors can generate disastrous consequences no less than physical harms.