“Defund the police” has become a rallying cry at protests around the country, a thorny art project in the nation’s capital and a cudgel that President Donald Trump is trying to wield against his opponents. The simplicity of the phrase belies the complicated nature of the debate. The “defund” movement runs along a spectrum, from those in Minneapolis who would disband and rebuild their police department (on the theory that the current department’s culture is too pervaded by racism and violence), t