And it could be changed so gradually that no one near retirement age or who has started planning significantly for it is affected. Even a glacial rate of change

And it could be changed so gradually that no one near retirement age or who has started planning significantly for it is affected. Even a glacial rate of change would help -- one month later every year for the next few generations. And delay the start by a few years. Point is to make changes without giving any cohesive group a strong reason to organize opposition. Or to have a strong moral argument that it was promised them.