Nostalgia, a term that originated as a medical diagnosis for Swiss mercenaries suffering from homesickness, is the sorrowful longing for a lost past. An April Pew survey found that nearly 6 out of 10 (58%) Americans think the country was better off for people like them 50 years ago. For Republican and Republican-leaning respondents, nostalgia for the early 1970s reached 72%.

Americans have always had a thing for the “good old days.” The problem is that what — or when — constitutes the “good old days” is a constantly moving target. It often seems to be about five decades earlier from right now.

Karlyn Bowman studies public opinion at the American Enterprise Institute. She found that in recent surveys, the 1980s and 1990s are starting to supplant the 1950s as the new “good old days.” You can see evidence for this all over the place in popular culture, from the remakes of old sitcoms to original offerings such as “Stranger Things” that cast those years as a lost time of innocence.

The simple fact is that nostalgia is a constant in American history. Politicians play on nostalgia because it is one of the most powerful human emotions.

I look fondly at my 1970s childhood, but it would be ludicrous for me to think such fondness was proof the country was doing better. When Americans say things were better 50 years ago, do they mean the runaway “stagflation” — high inflation plus low growth? The lines to buy gas? The Vietnam War? Watergate?

We hear a lot about rising crime these days. It’s a legitimate issue, but perhaps we’re nostalgic for the 1970s and 1980s not just because crime gets so much coverage but also because we’ve memory-holed the fact that crime was so much worse (maybe the lead poisoning from those days caused amnesia?). Violent crime exploded in those decades and has been trending mostly downward since 1993. In an 18-month period from 1971-1972, according to the FBI, there was an average of five terrorist bombings per day. In 1976, an FBI spokesman described San Francisco as the “Belfast of North America.”

Americans are richer today than decades ago. Adjusted for purchasing power, Mississippians — who live in our poorest state — have higher incomes than the French. We live longer, have more free time, and travel more affordably. Infant mortality has been cut in half; our air and water quality is vastly improved. Our cars are much better and much safer. Our homes are bigger and more comfortable. The number of people injured or killed on the jobs has plummeted. We’ve made real progress against racism in the last several decades.

None of this is to say today is perfect. Nor is it to say that everything has gotten better. Rather, it’s just to note that nostalgia is a terrible guide, because it tends to take progress for granted and replaces feelings for memory. Any politician who actually delivered the reality of the “good old days” would be pelted from office. Which is why it’s a good thing they can’t deliver on such promises.

Jonah Goldberg is editor-in-chief of The Dispatch