Credibility eliminates uncertainty

or rather - honestly incorporating uncertainty into forecasts or projections can undermine the credibility of the forecast. And worse:

It is known that perceived usefulness (which presumes credibility) in the eyes of policy makers often depends on whether the forecast (or other expert input) corresponds to the potential user’s preconceived beliefs, ...

This from the 2005 report of the National Academy of Sciences on decision making for the environment.

I knew it! Expressing prior beliefs as prior distributions is important. Now, what to do about undermining your own credibility by demonstrating the effects of users beliefs on your forecasts .. .