Examine Bostrom's Simulation Argument which posits that at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a posthuman stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history; or (3) we are almost certainly living in a computer simulation. Critically evaluate the assumptions behind these premises and discuss the implications for our understanding of consciousness and reality if proposition three is true.