In 2001 an Oxford Philosopher wrote a paper that I found as intriguing as it was annoying. It argues (convincingly) that one of the following propositions ‘must’ be true:

(1) the human species is very likely to go extinct before we achieve a ‘posthuman’ stage.

(2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof) – clearly unlikely given the types of games / simulations we already create!

(3) we are almost certainly living in a computer simulation.

Original paper is published here: http://www.simulation-argument.com/simulation.html