What’s on your mind this weekend, Bleeding Heartland readers? This is an open thread.

I’ve been thinking about how bad assumptions produce flawed theories and poor decisions. Steve Denning wrote an excellent piece for Forbes about Milton Friedman and the origin of “the world’s dumbest idea”: “that the sole purpose of a firm is to make money for its shareholders.”

Sean Trende, senior elections analyst for the conservative website RealClearPolitics, recently spun some rosy scenarios for Republicans worried about their party’s over-reliance on white voters. GOP candidates would be extremely foolish to count on his “racial polarization” scenario panning out. His “full Rubio” and “modest Republican outreach toward Hispanics” scenarios seem too optimistic to me as well.

High nitrate levels in Iowa waterways continue to make news, as they have for the last two months. I enjoyed this Des Moines Register editorial from Saturday’s paper. Excerpt:

During a meeting with The Des Moines Register’s editorial board earlier this year, House Speaker Kraig Paulsen made the claim that Iowa’s rivers are actually cleaner today than they were in the past. The evidence to the contrary is overwhelming. But Paulsen’s comment speaks to a troubling mentality that permeates the Iowa Legislature: If you just tell Iowans the water is OK often enough, maybe they will believe you and will think the lake they are swimming in doesn’t really smell like a toilet.

I don’t take my kids swimming in any Iowa lakes, and I won’t feel a bit sorry for Paulsen if he runs for Congress and loses the Republican primary, as I expect.