Here is a minor puzzle. The National Football League goes out of its way to say that officials erred and ought to have been swayed by video replays in a recent game. Judges (and here I will limit myself to appellate decisions) reverse previous decisions, though change is usually preceded by fine distinctions and nods to precedent. Legislators often vote for different tax rates or regulatory schemes, and manage to be proud of their flexibility. But U.S. Presidents and other world leaders (and indeed members of the executive branch quite generally) rarely admit mistakes or say they have changed their minds or approaches. For extra measure, religious leaders are also inclined to deny that previous pronouncements were mistaken.
I think these opening generalizations require some fine tuning (not to mention evidence), and I plan to provide much stronger and deeper claims in future academic work, but let's accept the generalizations for what they are, and see whether it is puzzling that differently situated decisionmakers, all ostensibly aiming to please similar audiences or do the right thing, should have such different practices with respect to mistakes, or change. In the spirit of blogging, I will try but one explanation here, and it relates to the role of transparency.
Referees do not normally walk off the field after a call and say they erred. And if their errors are apparent on television (a fact they normally discover too late) they will normally say that the angle they had on the field was different. They ask us to be like a factfinder deciding whether a defendant was negligent; try to eliminate information that developed after the act and put oneself in the shoes of the defendant at the time of the original activity. Seen this way, the interesting thing about the football league's admission is that the complaint is about what an official observed or should have seen in the video replay. The information available to the ex post critic is more or less identical to that available to the official on the spot - and it would therefore be almost silly to insist that the referee/official had not erred. Besides, most of us like to think that one can learn from mistakes, that we all make them, and that we value people who can admit to earlier errors.
It is especially easy for legislators to change without admitting "mistakes" because circumstances change. To vote for new tax rates is not to admit that last year's were mistaken. Besides, mistakes can be blamed on the group. The group dynamics are not transparent, so legislatures are more like the referee or umpire making a call on the spot, rather than reviewing an instant replay tape. The legislator can say "I am glad now to vote for Plan X; last year's Plan Y was the best we could do given where the center of gravity of the chamber was at that point (and that is something insiders know and you voters do not)."
Appellate judges are often somewhere in between. Circumstances change as information develops about the effects of legal rules, but of course a really good judge is supposed to think ahead as to how a legal rule will work. Appeals work is fairly transparent. Many commentators will see the same legal arguments the judge could have thought about at the earlier date, and it can be obvious that a decision is a bad decision. Panels are small enough, and multiple decisions common enough, that there is not much room to hide behind the group. Transparency generates confession and change. (Again, this is very rough and I welcome ideas for the fuller discussion I am working on.)
It is hardly surprising that religious leaders use precedent in its extreme form and rarely admit "errors." Many claim divine inspiration and this makes it virtually impossible to admit error, though it is possible (and common) to announce changed circumstances, much as legislatures do. If we like, we can think of divine inspiration as a means of non-transparency, and then attribute the disinclination to announce earlier mistakes to the non-transparency.
Presidents and prime ministers are entitled to make mistakes, but it is extraordinary how they hate to admit them. They do have the advantage of non-transparency, in that they can always say or imply "It may look like we went to war or adopted the wrong economic policy or allied ourselves with the wrong forces, but if you knew all that I knew at the time I made the decision, you would have agreed with me." Many of us will find this strategically puzzling, because we like to think that we would admire a leader who admitted errors (in policy making, as opposed to personal behavior, where confession normally follows sordid evidence and is a different topic) and simply said that he or she was doing the best under the circumstances. We are not ashamed of occasional errors in driving our cars or in choosing which car to buy or where to invest our savings, for example, so long as we did not engage in reckless behavior. Perhaps our politicians know us better than we do. Perhaps there is little to gain from confession (though cover-ups seem wasteful, at the very least). But it may simply be that without transparency there is no error admission.