To whom it may concern:
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.
(After the critical success of part II, and the strong box office sales of part III in spite of mixed reviews, will part IV finally see the June Open Thread jump the shark?)
It's nice to know I've had an influence :)
As it happens, I'm pretty sceptical as to how much we can know as well. There's nothing like doing policy to gain an understanding of how messy it can be. While the social sciences have a less than wonderful record in developing knowledge (look at the record of development economics, as one example), and economic forecasting is still not much better than voodoo but it's not like there's another group out there with all the answers. We don't have all of the answers, or even most of them, but we're better than nothing, which is the only alternative.
Nothing is often a pretty good alternative. Government action always comes at a cost, even if only the deadweight loss of taxation (keyphrase "public choice" for reasons you might expect the cost to be higher than that). I'm not trying to turn this into a political debate, but you should consider doing nothing not necessarily a bad thing, and what you do not necessarily better.