Analyze Nick Bostrom's Simulation Argument from a purely logical and probabilistic standpoint. Break down the trilemma 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; (3) We are almost certainly living in a computer simulation. Critique the assumptions underlying each branch of the trilemma without relying on pop-culture references.