The paper issue is theoretical and methodological basis of studies in suicide terrorism motivation and rationality, legitimized by radical Islam. Two methodological ideas are identified as dominant and defining paradigmal features of Western researches of suicide terrorism - the concept of rational actor and multi-causal approach. Concept of rational actor in most cases is interpreted through the sociological point of view: it takes into account a social group, not an individual. When individual motivation is viewed the concept of rational actor encounters a number of serious difficulties, so Western scholars came to an almost complete consensus that suicide terrorism is to be understood as organizational (E. Sprintzak) or crucially (though not exclusively) institution-level phenomenon (S. Atran). In multi-causal approach three levels of analysis are differentiated (societal, organizational and individual motivations). It is supposed that their consistent combination will give the key to understand the causes of suicide missions. But scholars failed to save parity between all the factors. They tend to overestimate the organizational level (strategic logic of organization, culture of martyrdom, etc). As the result, this approach leds as well as rational choice theory does to the sociologization of suicide terrorist rationality. Another tendency in suicide terrorism studies shows a strong influence of economist thought, based on liberal economic categories. This is typical for a rationalist approach. It means the reduction of extremist rationality (both at the organization and individual level) to a pragmatic rationality, calculating costs and benifits. Even T. Dronzina, who attempted to reconcile rationalist and culturalist approaches, eventually gives her preference for R. Harrison's economic theory of suicide terrorist identity. Suicide terrorism theories, even those which realize the limited character and non-applicability of the concept of rational actor to a suicide bomber, underestimate the anthropological and existential dimensions of extremist motivation. The author proposes a new approach to the interpretation of extremist rationality in suicide terrorism. He argues that a suicide bomber could not be qualified as a rational actor, but as an existential subject, who makes existential choice. Suicide bomber is a personality in limit situation (K. Jaspers) whose existence is on the verge of being and non-being. His (or her) rationality goes beyond the pragmatic mind, but based on metaphysical assumptions, in particular, on the act of renunciation of existence in this world, as a symbolic inversion of enemy domination to rule over him.
