From the very start of the Manhattan Project, the initiative was embroiled in questions concerning the ethics of nuclear development. The idea that a weapon could be developed and employed of such magnitude as to destroy entire cities in seconds, leaving them barren and poisoned by radiation, was a fearful one. In Countdown 1945, many of the key figures involved debate the ethics of the operation, some with wildly varying conclusions.

The principal objection to the use of the atom bomb in war was the perennial advice to consider the relationship between one’s choice of action and one’s desired outcome: i.e. the ends do not justify the means. This argument reasons that the desired outcome is not the only criterion for deciding questions of ethics—one cannot simply use any means indiscriminately just because it gets a good result. The critics of using the atom bomb pointed out it would result in the deaths of countless civilians: “Entire Japanese cities could be wiped out, millions of innocents destroyed, the landscape scorched and poisoned for decades after. The possibilities were disturbing” (81). Regardless of whether or not the bombing secured an Allied victory, it would be wrong no matter what.