Here’s something you might not know if you haven’t had a five-minute conversation with an 18-year-old in the past 12 months: America’s young know almost nothing about what happened before they were born, or even before last year.

This is not a stunning find about a group that thinks the first step of research is to type a few key words into a search engine and see what pops up, and that thinks that “oldies” are songs that were performed sometime in the 1990s. Of course young people know almost nothing about history. (Or grammar-school geography, for that matter. Doesn’t anyone expect anybody to identify the state capitals anymore?)

So I was not exactly stunned when I read that a perfectly reputable group, using perfectly simplistic methodology, came to the perfectly predictable conclusion that college freshmen were basically historically illiterate and that college seniors were little better (and, this fall’s juicy little twist: Some of the seniors know even less than the freshmen).

You needn’t use the 60-question test that the Intercollegiate Studies Institute administered to 14,000 students on 50 campuses to make that remarkable discovery. You need only ask the nearest 18-year-old whether she has even the remotest interest in watching a documentary about the Civil War or a show on the Kennedy-Nixon debates.

But you’re wrong if — and believe me, as the father of two young Americans, the temptation is there — you think it’s their fault. It’s not. It’s ours. They don’t have historical amnesia, because you have to know something to be able to forget it. They have historical ignorance, and we gave it to them.

Maybe, you might argue, that’s no big deal, because you can learn a lot of things by Googling, proof that having actual knowledge in your head — or, the way we used to put it, knowing something off the top of your head — is really overrated, or just out of date. Don’t know who followed Abraham Lincoln in the presidency? About six seconds on the Internet and you can come up with the answer — Ulysses S. Grant*.

But — and this is both the point of this new study and my quibble with it — there is more to understanding history than merely knowing facts. Facts are the raw material of history. But, just as coke is not steel, facts are not history. And truly the best way to understand history — and here the words know and understand do not mean the same thing — is to study it. Here’s a four-letter summary of the point that I will take more than 900 words to make: Read.

Don’t tell this to some of the professors on campus, happy in their selfless pursuit of knowledge for its own sake, but there actually is utility to historical knowledge. In showing how governments were created or overthrown, how movements began and faded away, how historical forces gathered strength and then petered out, history provides few lessons but much perspective. Your grandfather had a word for perspective, and if you were lucky he personified it: wisdom.

“There are some things people need to know to exercise responsible citizenship,” says retired Lt. Gen. Josiah Bunting III, former superintendent of the Virginia Military Institute, who serves as chairman of the National Civic Literacy Board. “Most of the kids we examined really know very little about the kinds of things that would make them responsible leaders. We didn’t ask silly trick questions. We asked the very basic questions.We gave them the phrase ‘We hold these truths to be self-evident,’ and asked where that came from. Less than 50 percent knew that. Less than 50 percent knew the century in which the first colony was established in Jamestown.”

This study of historical illiteracy includes the inevitable college rankings, a cheap technique designed to get attention for all the wrong reasons. These rankings, though susceptible to statistical illiteracy, are especially suited for that purpose, suggesting as they do that Grove City College outranks Princeton University. Indeed, Grove City students added 9.4 percentage points to their scores between freshman and senior years, while Princeton students added only 2.8 percentage points. Johns Hopkins University students actually lost historical literacy, forfeiting 7.3 percentage points between freshman and senior years.

I hope that the rankings (Rhodes College is No. 1!) aren’t a distraction from the real importance of this study.

In a world of cultural relativism and in a society that believes in electives both on campus and in life, it isn’t too much to ask that Americans know a little something about the Puritan religious tradition, the role of George Washington, the doctrine of separation of church and state, the thinking of Abraham Lincoln, the significance of Brown v. Board of Education, the contours of World War II, the concept of the separation of powers, the legacy of the Cold War and the role of Saddam Hussein.

Go ahead, call me old-fashioned. My answer is that it’s a shame that it’s the fashion to be so focused on the future that we no longer know what came before us.A shame — and dangerous, too, for the threats to the nation aren’t only in what we don’t know about the future. They’re also in what we don’t know about the past.

* Just checking to see if you were paying attention. Lincoln wasn’t succeeded by Grant. He was followed by Andrew Johnson. Knew it off the top of my head, but then again, I’m old.