To the question why so many people voted for Donald Trump, Democrats commonly reply: ignorance or lack of information — a deficiency of facts, of the knowledge necessary to make a reasoned decision. This was my working definition of ignorance until several years ago, when I began an email exchange with a childhood friend who is a passionate Trump supporter.

Bill went to college and has information at his fingertips. During the pandemic, he sent me the testimony of a doctor touting hydroxychloroquine for the treatment of Covid. He cited so-called experts claiming that the majority of violent crimes in America were committed by immigrants. After the January 6 insurrection, he drew on evidence produced by Rudolph Giuliani and others to argue that the 2020 election had been stolen and that violence on January 6 was the work of Antifa.

Today ignorance — at least in the political arena — seems to be generated by too much information rather than too little. By simply going online, people can acquire information that reinforces their opinions. The manufactured authority of an internet website is available to anyone with a computer. Ignorance isn’t just a lack of knowledge or experience; it’s an active, constantly growing presence across the technological media. Bill’s problem is not that he is uninformed; it’s that he is misinformed.

It happens that a relatively new field of study is dedicated to understanding this phenomenon. It’s called agnotology. According to Wikipedia, agnotology is the study of “deliberate, culturally induced ignorance or doubt, typically to sell a product, influence opinion, or win favour, particularly through the publication of inaccurate or misleading scientific data (disinformation).”

Although familiar to sociologists, the field of agnotology is unknown to most people. The term first appeared in print in 1995 but the phenomenon it explores has of course existed throughout history. Charles Dickens devoted himself to satirizing willful ignorance, blinkered rationalism, and bald-faced denials of the truth. After Dickens depicted the notorious London slum known as Jacob’s Island in “Oliver Twist,” a former London mayor insisted that no such place had ever existed. In response, Dickens wrote a new preface to the novel in which he reassured readers that Jacob’s Island wasn’t made up.

I came across the word agnotology in an illuminating work of literary criticism called “Hidden in Plain Sight” by John T. Matthews, a study of how 19th century American writers used literary form to confront one of the most glaring contradictions in our republic’s history: its dependence on a slave economy. In his Introduction, Matthews writes: “A phenomenon I’ve encountered regularly, not only in literary form but in media representations, is the anxious concealment of disturbing knowledge in plain view — knowledge displayed so openly that … it is given no attention.”

Matthews goes on to cite the example of a video clip of President George W. Bush declaring an ecological initiative at a national park at the same time that his administration was rolling back measures to protect those very forests. And Matthews’ book ends with another disturbing example of cynical, open concealment: Melania Trump’s decision to wear, on a visit to a camp for impounded migrant children separated from their parents, a jacket that says, “I REALLY DON’T CARE, DO U?” Mrs. Trump’s spokesperson, of course, insisted there was “no hidden message,” and she was perfectly right. The message was not hidden.

Matthews ends the book with the arresting sentence, “The problem remains how to reveal what is already hidden in plain sight.” Great writers know how to reveal it, as do the great comedians of our day. But what about the rest of us? We read and study, we talk, we write, we make calls to congressmen and senators, we head out to protests. We become activists ourselves in order to fend off the daily onslaught of disinformation and misinformation.

Others are activists in the opposite direction. Recently, after the initial response to Trump’s tariff announcement, I sent Bill a statement by a renowned economist who said, in effect, that there is not an economist alive today who thinks Trump’s tariffs are a good thing. But Bill went online and quickly found one: a self- designated authority on economic issues who proclaimed the benefits of tariffs.

Ignorance is cheap these days. It’s a buyer’s market.

Julia Brown is a professor emerita of English at Boston University. She lives in Northampton.