TIM KRIEGER Calculating the Costs of 9/11 September 11, 2001, was a day of unprecedented shock and suffering not only in the history of the United States of America (cf. National Commission xv), but to people all around the world. Using airplanes as deadly weapons, terrorists hit the very heart of the New York City financial district, the World Trade Center’s Twin Towers, as well as the Washington Pentagon, while a further attack on an- other symbolic place on U.S. soil could be prevented by the brave passengers of United Airlines Flight 93. The impact of the collapse of the Twin Towers to an unprepared nation was so enormous that there was – and still is – a widespread belief that the events of 9/11 constituted a turning point in history (cf., for ex- ample, Habermas 4). In fact, even ten years after the 9/11 terrorist acts 58 per- cent of Americans believed that the attacks had fundamentally altered the way people in this country lived their lives; and since 2001 there has been no de- crease in the percentage of Americans who say they have permanently changed the way they live their own lives (cf. Jones). Compared to the 9/11 terrorist attacks, other important events in the history of transnational terrorism, such as the Lockerbie bombing with 270 fatalities on 21 December 1988, appear relatively minor despite their significant – mainly polit- ical – impact. Similarly, the first terrorist attack on the New York World Trade Center on 26 February 1993, or the later Al Qaeda-related bombings in Madrid (11 March 2004) and London (7 July 2005) did not attract the same level of at- tention and did not cause comparable political, economic and social damage. Despite the large number of victims of the 9/11 terrorist attacks, it is striking that the impact of these events is so much stronger, longer-lasting and felt by so many people all around the world even until today. Accordingly, the aim of this essay is to analyze not only the costs and consequences of the attacks to U.S. society and the international community, but also to explain why and how they differ from comparable events, that is, why 9/11 might indeed be considered a turning point in history, as claimed by Habermas and others. In order to better understand the impact of the 9/11 attacks, I argue in the pre- sent essay that 9/11 is characterized by an unprecedented interplay of several contributing factors. First, as terrorism causes significant costs to society in gen- eral, this was also true for 9/11. The cost component has several dimensions ranging from the destruction of human and physical capital to a reduction in life satisfaction due to increased levels of fear: as of 2011, almost 40 percent of all Americans still worried that they themselves or their family members could be- come victims of terrorism (cf. Saad). Closely connected to this aspect is the se- cond contributing factor: psychological effects that are related to the occurrence