This sort of anthropic reasoning is wrong. Consider the following experiment.
A fair coin is tossed. If the result is H, you are cloned into 10^10 copies, and all of those copies except one are placed in the Andromeda galaxy. Another copy remains in the Milky Way. If the result is T, no cloning occurs and you remain in the Milky Way. Either way, the "you" in Milky Way has no immediate direct way to know about the result of the coin toss.
Someone, call her "anthropic mugger", comes to you an offers a bet. She can perform an experiment which will reveal the result of the coin toss (but she hasn't done it yet). If you accept the bet and the coin toss turns out to be H, she pays you 1$. If you accept the bet and the coin toss turns out to be T, you pay her 1000$. Do you accept the bet?
Reasoning along the same lines as you did to conclude there are no large civilizations, you should accept the bet. But this means your expected gain before the coin toss is -499.5$. So, before the coin toss it is profitable for you to change your way of reasoning so you won't be tempted to accept the bet.
There's no reason to accept the bet unless in the cloning scenario you care much less about the copy of you in Milky Way than in the no-cloning scenario. So, there's no reason to assume there are no large civilizations if the existence of large civilizations wouldn't make us care much less about our own.
There are a number of problems with that:
1) You don't specify whether the bet is offered to all my copies or just to one of them, or if to just one of them, whether it is guaranteed to be the one in the Milky Way. Or if the one in the Milky Way knows he is in the Milky Way when taking the bet, and so on.
Suppose I am offered the bet before knowing whether I am in Andromeda or Milky Way. What odds should I accept on the coin toss: 50/50? Suppose I am then told I am in the Milky Way... what odds should I now accept on the coin-toss: still 50/50? If you say ...
The 'Irrationality Game' posts in discussion came before my time here, but I had a very good time reading the bits written in the comments section. I also had a number of thoughts I would've liked to post and get feedback on, but I knew that being buried in such old threads not much would come of it. So I asked around and feedback from people has suggested that they would be open to a reboot!
I hereby again quote the original rules:
I would suggest placing *related* propositions in the same comment, but wildly different ones might deserve separate comments for keeping threads separate.
Make sure you put "Irrationality Game" as the first two words of a post containing a proposition to be voted upon in the game's format.
Here we go!
EDIT: It was pointed out in the meta-thread below that this could be done with polls rather than karma so as to discourage playing-to-win and getting around the hiding of downvoted comments. If anyone resurrects this game in the future, please do so under that system If you wish to test a poll format in this thread feel free to do so, but continue voting as normal for those that are not in poll format.