Should the United States have developed the nuclear weapon?

Should the United States have developed the nuclear weapon? The U.S. have developed it during the course of World War II as part of the Manhattan Project, starting in 1941.

Variants: Why did the U.S. develop the atomic bomb?

Key notions and distinctions: nuclear weapon, fission nuclear weapon, thermonuclear weapon, strategic nuclear weapon, tactical nuclear weapon, development, use, deterrence, proliferation, non-proliferation, ban, testing, destruction, disarmament, fission, fusion, uranium, plutonium, hydrogen, radiation, cancer.

Arguments for

 * This discussion is futile. The development was unstoppable.
 * Not obvious. Needs to be demonstrated.
 * Given the risk of Germany's developing its own fissile nuclear weapon, it was the proper precautionary step to take.
 * That assumes that the American nuclear weapon would serve as a deterrent to the semi-insane Hitler. That is far from clear.
 * Better to have a possible deterrent for a semi-sane Hitler than to have no deterrent.
 * The Manhattan Project to develop the bomb was presented to the U.S. president by the genius physicist Albert Einstein. He was persuaded by other scientists, also luminaries. It is even stronger given that Einstein was a pacifist and opposed making a weapon in principle, but saw that pacifism was no defense against Hitler's aggression. That is not conclusive yet suggestive.
 * And yet, according to at least one source, multiple scientists working on the Manhattan Project objected when they learned about the purpose.


 * The nuclear weapon created a lasting peace by creating a nuclear deterrent.
 * The peace lasts only so long as the risk created was not triggered by the relevant chance events in the world. There is enough time; the nuclear mutual destruction can wait for its chance, figuratively speaking.
 * The nuclear weapon enabled subsequent development of nuclear energy.
 * Even if we assume that nuclear energy is a good thing, it is not worth the risk of an all-out nuclear war.
 * Without the nuclear weapon, the war could not have been ended so swiftly in Japan, which would result in great loss of American life.
 * The saved American lives are not worth the risk of an all-out nuclear war, an event with impacts on a different order of magnitude.
 * U.S. could have refrained from invading Japan islands. That would have saved American lives as well.

Arguments against

 * Avoiding the threat of nuclear war that arose as a result was worth taking the risk and not developing the nuclear weapon. Instead, the U.S. should have created pressure on other countries not to develop their own nuclear weapons. Furthermore, it could have been the technology developed in the U.S. that was a stolen secret that enabled the nuclear weapons program in other countries.
 * Pressure on the wildly aggressive Hitler's Germany in 1941 does not seem to be meaningful options.
 * The implied principle that one must develop a dangerous weapon since otherwise others will have it first is a recipe for the destruction of the surface of the Earth. Since, each further escalation of destructive power is justified using this generic reasoning, instead of seeking international bans on development of such a dangerous technology.
 * A fair point. However, further development of dangerous weapons is perhaps easier to give up by a country that became a global hegemon by means of less dangerous weapons. And it is easier to give up in conditions where the most destructive weapons are already so destructive that they are more of a deterrent than a weapon to be actually used.
 * And yet, they developed the thermonuclear (fusion) weapon when they already had the fissile weapon.
 * If the U.S. was really concerned about Hitler as a danger, they should have joined the European war as soon as possible instead of taking a step toward developing the immensely more destructive weapon much later, the thermonuclear bomb. Instead, the U.S. entered WWII in December 1941, and in fact, it was Germany and Italy that declared war on the U.S.
 * The large-scale U.S. atomic project did not begin until December 1941. Thus, both actions were taken.