The act of killing can wreak immense psychological damage upon rational individuals  To know that one has actually killed another human being will haunt the moral agent forever. Instances of Post-Traumatic Stress Disorder for soldiers returning for warzones are increasingly reported, suggesting that a situation of killing very often warps the killer’s life [1] . This holds true even for people not directly and viscerally involved in killings, such as the incredible guilt felt by the team of the Manhattan project. [2]  [1] ScienceBlog, ‘1 in 5 Iraq, Afghanistan Vets has PTSD’, 17 April 2008,   [2] Long, Tony, ‘Aug. 6, 1945: ‘I Am Become Death, Destroyer of Worlds’, Wired, 6 August 2007,