A good health care plan that is practical, not too far from politically feasible, and applies competion to lower costs and improve service quality. It must be incentive-compatible, yet at the same time it can't be seen as heartless and simply letting people die.
I am working on a monograph on health care policy, for one of the infamous think tanks. I am coming around to the view that there is no health care plan that is politically feasible. The American people believe that they have a God-given right to as many health care services as they want, paid for by someone else. As an economist, the best I can do is point out how this belief stymies health care pollicy. But in the absence of cultural change, Tyler's constraint binds too tightly.
Or consider another one of Tyler's challenges.
How can Africa actually develop? Don't beg the question by listing the needed outputs -- such as markets, democracy, or the rule of law -- as the inputs of your policy recommendation.
This begs the question of who is to be the recipient of the "policy recommendation." Are we to assume that we are advising Robert Mugabe? Or are we advising the American State Department on how to influence policy in Zimbabwe? In either case, the constrained optimization problem is almost insoluble.
The thrust of Tyler's constraints seems to be that economists need to offer ideas that are practical and implementable under current political conditions. That is one model, but perhaps not the only way to view policy development. Another role that we can play is to try to educate people so that political conditions do not impose such tight constraints.