Because he didnt want America to be dragged into any other country's wars.If America joined the league of nations then one of the rules being a member was....any country that was in league of nations goes to war, all countries that are members are to go to war and back them. Therefore forcing a country into wars of other countries. Once you join the league of nations you are a immediate alliance to all countries in league of nations. Lodge wanted it to be a choice congress makes to go to war...not league of nations. It woukd give up our right to choose if the fights were worth our benefits