When we get nostalgic, we tend to overlook bad times and focus on good memories. It’s like how Green Day’s “Good Riddance” ended up promoted under its subtitle, “Time of Your Life”… and then became the go-to ballad for every late 90s graduation, flashback, and farewell television episode.

In a recent op-ed for the New York Times, historian and Council on Contemporary Families co-chair Stephanie Coontz reminds us that a little personal nostalgia may be fine, but we should be wary when everyone starts longing for the “good old days”:

In personal life, the warm glow of nostalgia amplifies good memories and minimizes bad ones about experiences and relationships, encouraging us to revisit and renew our ties… In society at large, however, nostalgia can distort our understanding of the world in dangerous ways, making us needlessly negative about our current situation.

This nostalgia doesn’t just make the present look worse. It can make it harder to see some pretty spectacular screw-ups:

I have interviewed many white people who have fond memories of their lives in the 1950s and early 1960s. The ones who never cross-examined those memories to get at the complexities were the ones most hostile to the civil rights and the women’s movements, which they saw as destroying the harmonious world they remembered.

But others could see that their own good experiences were in some ways dependent on unjust social arrangements, or on bad experiences for others… These people didn’t repudiate, regret, or feel guilty about their good memories. But because they also dug for the exceptions and sacrifices that lurked behind their one-dimensional view of the past, they were able to adapt to change.

Trading in rose-colored glasses for 3D might let us accept a fuller version of the past and more possibilities for the future.