Detail Nick Bostrom's Simulation Argument, which posits that at least one of three propositions is true: (1) The fraction of human-level civilizations that reach a post-human stage is close to zero, (2) The fraction of post-human civilizations interested in ancestor simulations is close to zero, or (3) The fraction of all observers who live in simulations is close to one. Critically evaluate the logical structure of this argument and discuss objections regarding the nature of consciousness and computational substrate independence.