I have been thinking lately about all the people who by some dark mechanism have managed to willfully blind themselves to what is directly in front of them.

The ones who insist X is white when our eyes tell us it’s black, and vice versa. And when we object, they call us “idiots.”

It would be laughable — like a hagfish calling us ugly — if the people putting it out there with their blinkered view of the world were not fomenting societal fractures and setting us against each other.

But they are.

It is not new, this tendency, and the litany of blockheaded ideas this trait has sprung over the centuries is long and tragic, often served up with a wrongheadedness so ridiculous that the prevailing tendency of the listener is to yearn for a hole to open up, or to find a brick wall nearby to ram his or her head against.

Again, not from what the world shows them, not from actual evidence, but from the bias and prejudices streaming from their skulls that they then project on the world and misread as “truth.” Thus, they paper over the glaring faults of moral misfits and criminals and malign people they’ve never even met before.

Among these persistent biases over the centuries has been the one that maintains that women are not as smart as men.

Seriously, where does this clunker come from? Not from the world we live in, that’s for sure. Look around, look beyond your nose, look beyond your front door, examine all fields of human endeavor, you will find no shortage of very sharp women. I was lucky enough to grow up with three of them, and to marry one.

In his masterwork, “Anna Karenina,” Leo Tolstoy wrote — as a counterweight to the tragedy of Anna — of a young couple, Levin and Kitty, and what their new marriage was teaching him about her.

In one chapter of that book, Levin refuses to allow Kitty to join him on visit to his dying brother because he was convinced that the fragile flower he imagined his wife to be would not be able to handle the grosser responsibilities of palliative care.

Levin’s initial refusal kicked off a terrible argument between them. When he finally relented and allowed Kitty to join him, he would discover to his astonishment how remarkable she was in her unflinching care for his dying brother, and how much tougher she was than he had imagined.

What manner of being had he married, Levin wondered. On entering married life, he had thought, in line with the prevailing prejudices of 19th-Century Russia, that Kitty would need nothing but his love. It had never occurred to him that she, too, had her own mind, that she would not always agree with him, and that she, too, would want something to do in their married life beyond soaking up his adoration.

I think also of the prejudice at the time of the Civil War, which held that Black soldiers would not fight but run away in the heat of battle. The actual heroism Black soldiers displayed during the war should have dispelled that and other wrongheaded ideas. Nevertheless, the prejudice persisted not only through that war, but into all other wars in which Americans have fought. Indeed, prejudice still stains our national life.

Having seen bigots confront people of other races, I can reach no other conclusion than that they were superimposing their own projections over the faces of men, women and even children, and consequently never saw the flesh and blood human beings in front of them.

It’s tragic to see human beings fortify their biases in the teeth and forehead of all evidence to the contrary. Tragic, because in the end it is a refusal to learn from life, and to rise to better versions of ourselves.

Robert Whale can be reached at rwhale@soundpublishing.com.