Conventional wisdom is that the United States can never solve its problem of gun violence. But it was conventional wisdom that we'd never end slavery, allow women to vote, enact civil rights laws, reduce pollution, prohibit smoking in public, elect a Catholic or black President, or allow gay people to marry. Fundamental change often takes generations. We must do our part to advance the discussion. Just because we can't solve the problem now doesn't mean we won't eventually. President Obama often quotes Dr. King, who said that "the arc of the moral universe is long, but it bends toward justice."