There can yet be a silver lining to the Tucson massacre if we stop trying to exploit it for political purposes and instead seize upon it as a fresh chance to change our culture of violence — too much hate, too many guns, too many killings. The bitterness in politics is part of this larger trouble. There is no evidence it prompted Loughner — and the finger pointing should stop — but we knew long before Tucson it must be cleaned up. In coming weeks, President Obama should invite GOP leaders as well as chieftains of entertainment and news, the NRA and others to see if we can reach a higher plane. America will always be rough and tumble — that's in our DNA — but generations past have proven we can also be a noble people.