I had a conversation with someone this morning about one way you could tell whether you're in a simulation. If you look close enough at an object, possibly you'll see the resolution break down at fine scales, revealing that you are in a simulation. I used the very low-tech method of looking closely at two other people's irises, as well as the edge of a safety seal on a food container. No doubt CGI artists would have told me to look at hair as well. Finding no resolution breakdown, I concluded that I was not in a simulation.
Right now you may be thinking that this is an incoherent way of investigating and arguing this point, but forgive me. The funny part about is that I was dreaming all this, so that I absolutely was in a simulation! When I woke up I started laughing out loud at the irony.
Point: Bostrom, and maybe Chuang Tzu.
[This turned into an interesting discussion on my Facebook page.]
Above: What your blogger looks like when he's awake.