Russ Roberts is almost apopleptic at the sight of 650 "economists" signing a letter that only an economic illerate could have signed.
He proposes founding a new society that any economist can join provided they hold the following three beliefs:
1. Demand slopes downward - people do less of something when it gets more expensive
2. Prices respond to market forces
3. Motives and intentions do not matter. Results and actions do.
Russ's third point is the most important. I find the most effective way to make the muddle-headed realise their closely-cherished political/economic beliefs are wrong is to make them realise there is a BIG difference between "intent" and "outcome".