Last year, the Philadelphia City Council passed a bill requiring the licensing of tour guides in the historic area of the city. The legislation created a requirement for guides to be periodically tested on their historical knowledge. Some of the debate around the legislation was predictably concerned with the size and prerogatives of government and the cost of additional bureaucracy. I found myself more concerned with the proposition that what we want from tour guides is a testable adherence to concrete historical facts. Perhaps perversely for a professional historian, I think that a few tall tales and imaginative shadings from the guides at Philadelphia’s historic sites are not only inevitable but a potentially positive part of the ongoing creative renewal of historical knowledge.

To start with, I’m skeptical about what this test ought to test for. Think of a fact about Philadelphia in the colonial era. That Benjamin Franklin lived in a house now marked by a sculpture at Franklin Court? Certainly. That George Washington kept slaves at his presidential home when Philadelphia was the capital of the United States? Absolutely. That colonial Philadelphia was a part of a larger Atlantic political economy that was crucially shaped by slavery throughout the Americas? Very much a fact. That the lives of ordinary residents of late colonial Philadelphia was considerably different from the lives of Franklin and other members of the city’s elite? Certainly as well.

I’m not suggesting that your average tour guide, clip-clopping around Independence Hall in a horse-drawn buggy, should offer a lecture on mid–18th-century social history.

It’s just that if we want guides or other people to know “facts,” that, in and of itself, doesn’t tell us much about which facts matter or which facts are appropriate to what context. There are a lot of facts, after all.

Periodically, civic and political groups issue the results of surveys that suggest the American public is ignorant about history. It’s often implied that this is an accelerating trend, but this is very difficult to say, both because such tests haven’t been standardized across a long time span and because those results that have been reported don’t really typically demonstrate progressively greater ignorance in recent years. At the least, if a lack of knowledge about dates, facts, and events is a continuous condition in modern American life, it begs a question about whether there are any meaningful consequences to such ignorance. Perhaps Henry Ford was right, and in a country known for reinvention, history is bunk. More pointedly, perhaps the 19th-century French intellectual Ernst Renan was right when he observed that nations need history but that they generally need to get it wrong, so as to forget aspects of the past that would call into question the unity or coherence of the nation-state.

However, I think there’s plenty of evidence that Americans do care about history, often passionately so, and that when historical concerns rise to the surface, they often demonstrate a deep and complex understanding of the American past that rests both on the formal knowledge of historians and on the memories of communities, families, and individuals. This can very much include the signature events and names of American history, as the commercial success of Ken Burns’ series The Civil War or a number of recently published biographies of the Founding Fathers suggests.

Public history, as in museum exhibits, monuments, and memorials, can be a particularly intense focal point for this kind of engagement. We care a lot about how the Smithsonian exhibits the history of the atomic bomb or about how to mark the Vietnam War in Washington. We care about how—or whether—to make a gigantic statue of the Native American leader Crazy Horse and about which buildings and places deserve preservation because of their links to the past. And when people care, they care about getting it right in a more expansive and vital way than a simple inventory of the facts.

It’s often true that such public representations of the past contain factual inaccuracies or that they mythologize and misremember aspects of history. But not all inaccuracies are created equal. Historian Richard Slotkin argues in his 2002 essay “Fiction for the Purposes of History” that part of the professional training of historians should be writing historical fiction because such work opens up other kinds of truth through other voices and modes of representation. When we build memorials, visit historical sites, visit museums, stage reenactments, or travel somewhere to see and experience the past, we’re trying to do something similar to what the best historical fiction does—to bring history inside our hearts and lives, to think in a new way about its meanings.

I once had a conversation with another historian who pointed out that Cape Coast Castle in Ghana was relatively unimportant in the history of the Atlantic slave trade—that far greater numbers of slaves were transported from other sites in West and Equatorial Africa. He conceded that at many of these other sites, there is little physical evidence today of that history and that other sites would be relatively inaccessible to contemporary travelers. Thus, Cape Coast Castle has become an important stop for African American tourists on trips to West Africa, a solemn opportunity to think about the history of enslavement. Slaves were held in Cape Coast Castle: it was a part of that world. The feel and look of that building today is an important portal into that history, a chance to make visible a history that is otherwise so deeply embedded in the modern world. A narrow vision of historical fact shouldn’t bar the way to that opportunity.

Slotkin argues that historical fiction lets us access the power of history that resides in its mythic or poetic resonances with the present. It lets us create new myths or challenge old ones. When we set out to understand what we are and what we might yet be, we draw on the stories, characters, and lessons that the past provides. When we decide what we honor or despise, fear or treasure, we often turn to history. I once went hiking with family along a hilly back road near Death Valley in California. We came upon a short, abandoned mineshaft that was somewhere between 60 and 100 years old, apparently dug with hand tools by no more than a few individuals. That mineshaft, hundreds of miles from any settlement or community, is likely the only trace of the men and labor and dreams spent in that lonely, desolate place. If I wanted to say anything vividly individual about that history—as opposed to something systematic and abstract—I would need an imagination that goes beyond the kind of facts that could compose a concrete test for tour guides.

However we call upon history, it still requires careful study, is still constrained by the factual substance of the past. History isn’t just any damn thing we please. Some of what we imagine through history is wrong because it so grossly or wildly misrepresents the truth of the past. Expert knowledge about the past is still important; it provides substance that everyone can use to flesh out memory and imagination. There are things we don’t know about the past and things we can’t know, and everyone should recognize those boundaries.

Of course, a perfectly truthful representation of some aspects of human history can also be used in service to a repellant vision. For example, a racist could be rigorously factual in a description of past massacres of Native Americans and then argue that because this “solved” the problem of Native Americans, this is exactly what the government should continue to do now with nonwhites. What’s wrong here is not the command of facts, it’s the ethics of it. Some of the dreams and myths we make with history are inherently bad not because they misrepresent the past, but because they are morally odious.

If a guide to historic Philadelphia adamantly denied that there were any slaves in Washington’s house or claimed that Franklin was having a love affair with Queen Ranavalona III of Madagascar (born after Franklin’s death), that guide would be malicious in the first case and silly in the second. But a guide who offers more plausible if slightly embellished tales of Franklin’s romantic escapades or other mythic shadings of the lives and times of 18th-century Philadelphians isn’t doing anything that we should call to heel. The tree of history is nourished by dreams and stories as well as by facts.