"In the 1980s, the social and political philosopher Jon Elster brilliantly generalized the idea of adaptive preference in terms of the complementary phenomena of "sour grapes" and "sweet lemons": We tend to downgrade the value of previously desired outcomes as their realization becomes less likely and upgrade the value of previously undesired outcomes as their realization becomes more likely."<p>Its like the shifting baseline effect. Each generation thinks there's a lot of fish in the harbor because they never saw how mush there used to be.