I don't think I understand your question. There appear to be upper limits to how easy it is to solve certain kinds of problems that an intelligent agent would want to be able to solve. It is uncertain whether we have discovered the most clever methods of solving these problems - for example, we aren't certain whether P = NP. Apparently, many mathematicians think humanity has been basically as clever as is possible (i.e. P != NP).
If we think there are limits, faul_sname asks the obvious next question - is human-level intelligence anywhere near those limits? I don't see why not - intelligence has consistently shown reproductive fitness - so I expect evolution would select for it. It could be that humanity is in a local optimum and the next level of intelligence cannot be reached because the intermediate steps are not viable. But I'm not aware of evidence that the shape of intelligence improvement was like that for our ancestors.
intelligence has consistently shown reproductive fitness - so I expect evolution would select for it.
Yes, but the speed at which it would do so is quite limited. Particularly with a generational time of 15-25 years, and with the fact that evolution basically stopped working as an enhancer once humans passed the threshold of preventing most premature deaths (where premature just means before the end of the reproductive window).
What makes you think that the threshold for civilization is anywhere near the upper bound for possible intelligence?
I was very interested in the discussions and opinions that grew out of the last time this was played, but find digging through 800+ comments for a new game to start on the same thread annoying. I also don't want this game ruined by a potential sock puppet (whom ever it may be). So here's a non-sockpuppetiered Irrationality Game, if there's still interest. If there isn't, downvote to oblivion!
The original rules:
Enjoy!