You have to show violence the way it is. If you don't show it realistically, then that's immoral and harmful. If you don't upset people, then that's obscenity.
As quoted in Shakespearean Criticism : Excerpts from the Criticism of William Shakespeare's Plays and Poetry, from the First Published Appraisals to Current Evaluations (1985) by Laurie Lanzen Harris, p. 11