1.President Truman decided to drop the bomb down because He knew that invading Japan was not an easy task due to the geographic situation of it and the american army was to weary after four years of fighting, even with americans in control of the main cities in Japan, japanese soldiers denied to give up, so the Truman saw the throwing of the bombs as one solution to end the war once and for all. .
A valid argument for the using of atomic bombs would be, for protecting the life of american soldier and to show Japan that for them the best solutions was to give up.
2. Arguments that can be made against the use of atomic bombs, there are several.
The main and most important is to recognize that chemical weapons not only affect the place where they were released, sooner or later the effect will spread and nobody knows the damage they are making to the planet. but do not forget also the damage they do at immediate term.