A lethal Rube Goldberg machine may work in many steps, it may be full of thousand year fuses and randomizers and alternatives waiting in reserve, its working may require the responses of unsuspecting agents, there may be no way to discover how it is built or understand how it would work; and yet it may be no less stable and durable for all that, and the causal chain running through it may be far more independent of intervening coincidental events than are most of the causal chains in the wider world.