One of the best rules of thumb to emerge from systems theory is Stafford Beer’s famous statement: the purpose of a system is what it does. It doesn’t matter what the designer intended, or what the individual participants think they’re doing; the end result is all that matters. It’s a useful thing to bear in mind when we consider the objectives of the Black Lives Matter protesters, because right now the movement is beginning to look an awful lot like a machine for the abolition of police departments.