I am surprised that this post appeared on OB, and even had (independently) a comment about staking money on predictions and a comment written by Robin Hanson, without eliciting a mention of ideas futures. So I'll go ahead: if you actually care about predicting the future--or just getting people not to listen to silly predictions--I suggest creating and consulting a market. If social and institutional barriers make this proposal infeasible or unhelpful, I suggest chipping away at them (or at least thinking about how effectively you could chip away at them).