Father, I must confess: I have made comments on social media.

There is at least one thing that social media illuminate, and that is the unwillingness or the incapacity of people to reason. I attribute it in part to “critical thinking,” which turns otherwise intelligent people into perpetual sophomores, ready to play what they think is the ace of trumps, but what is actually a dog-bitten Monopoly property card for Marvin Gardens when the game is bridge. It is a plexiglass Cone of Silence over the brain; nothing gets in and nothing gets out.

A case in point. The subject today was abortion. A woman burst out, “What century are you living in? Do you actually believe”—and let’s stop right there.

The person’s implicit premise is that people grow wiser, nobler, more righteous, and kinder to puppies with each passing generation. Otherwise why bring up the business about a century?

Let us ask this person, call her Missy, to tell us about other peoples and other centuries. “Missy, are you saying that Athenians of the fourth century B.C. were better than Athenians of the fifth century B.C.? Or, to bring things closer to us, are you saying that Italians in the 1400s were better people than were Italians in the 1300s?”

Missy can now make one of several moves. She can flounce out of the room. She can say, “I am not talking about Athenians or Italians.” She can say, “I guess that they were better.”

If she flounces out of the room, you return to reading The Brothers Karamazov while you take a sip of gin and tonic.

If she says she is not talking about Athenians or Italians, you may ask what she has against Athenians and Italians, seeing as she seems to have exempted them from her rule, which is that moral progress in human affairs is smooth and inevitable, like the flow of water down a hill, with fish bones and paper wrappers and other dead things floating along with it. Were the Italians during the age of the Medici crime family, the popes with bastard children, and warlords such as Gattamelata or mercenaries such as John Hawkwood, better than the Italians of a century before?

Of course she will not know about the Medici crime family. She may at this point say, “I don’t know enough about Athenians and Italians to give you an answer.” At which point she has surrendered; the principle is established. You cannot tell by the clock whether Nation X is better or worse than it was before. You have actually to know things—you have to know how the people live.

But she may say that they must have been better, sticking to her quaint and childlike trust in inevitable progress. So you say, “All right then, let me ask about the length of time in question. You know that we group years into centuries for the wholly accidental reason that we have ten fingers and not twelve.” This may require some explanation, but press on anyway. “So why should one hundred years matter? Why not ninety years, or eighty years?”

She may now tilt her head like a Labrador retriever, suspecting a trap, sniffing, curling the lip just a bit to show the end of one tooth, like a hook.

“Why not twenty years? After all, people will say, What decade are you living in?”

“All right,” she says. “So?”

“So was Germany in 1930 a better place than Germany in 1920, just because it was 1930 and not 1920? Was the Soviet Union in 1920 a better place than Russia in 1910, just because it was 1920 and not 1910?”

“You are trying to confuse me.”

“No, I am not. You are already confused. I am trying to establish a principle. There is no inevitable moral progress in human affairs. This is a principle you yourself accept, although you do not know it.”

“Why do you say that?”

“Because you say that if we outlaw abortion, which we could well do, we would be, according to your way of looking at things, a worse people than we had been before. We would have regressed in private morality and public justice. Now, you are wrong in that evaluation, but the very fact that you make it shows that you fear that moral progress is hard-won and is always under threat.”

“But what difference does all of this make? Why do you oppose a woman’s right to choose? This isn’t the Middle Ages, you know!”

“There you go again. What time is it?”

“Three o’clock.”

“Did the moral law just change when the clock struck three?”

“That’s stupid.”

“You are, I wager, an admirer of the American Indians.”

“Yes, and why not? Are you a bigot also?”

“Far from it. I admire them too. They do not live the same lives they used to.”

“No. A lot of them live on reservations. That’s another crime of white males”—but you cut her short.

“Let us assume then that we can learn a lot from the way the Indians used to live. Would you agree?”

“Of course I agree!”

“But they no longer live that way.”

“No, they don’t, because we robbed them of their land and we,”—and again you cut her short. You have to, because eventually the world will come to an end.

“My point is that we can learn from people who do not live as we live now. If that is the case, then when they lived is of no consequence. Do you believe that we have nothing to learn from, say, the natives of Kenya or Tanzania?”

“Of course not! I’m not a racist.”

“So it’s not important, where people live. They could be Inuit living on the shores of Baffin Island, or aborigines living in the Australian outback, or natives of Borneo living in the jungles. The point is not where they live, but how they live.”

“So what?”

“So, what applies to place applies also to time. It does not matter.”

“But we know more than we used to know!”

“Yes, about, let’s say, how electrons can be made to move in a wire. By the way, can you explain to me how we can use the flow of water over a dam to make electrons move in a wire?”

“No, not really.”

“That’s all right. Not many people can; our schools aren’t what they used to be. But let’s say that John over there knows how we can use the flow of water over a dam to make electrons move. Will you now trust John with the keys to your home? Will you give him the password to your bank account?”

“Of course I wouldn’t. I don’t know what kind of a person he is.”

“Ah, so then knowing how electrons move in a wire is not the same as knowing what is good.”

“What does this have to do with anything?”

“You have said that we know more than we used to know. I am saying that we do not necessarily have a better idea of what is good and what is bad. After all, you yourself have admitted that we might learn plenty from people who not only did not know how electrons would move through a wire, but had no wires for them to move through, and no dams either.”

“I’m tired of this. All this is just a lot of words.”

“No. It is a lot of thought. What you put forth at first was nothing but words, meaningless words. You are the one who said that we have nothing to learn from people who do not live as we live now. You didn’t put it that way, because you are a nice person and you probably have a good digestive system, or you’d have walked out on me by now, but that is what your words implied, and that, as you yourself have said, is nonsense.”

“Then where are we?”

“We are where we started. You wanted to argue for the moral permissibility of abortion. Go ahead and try.”

Make people make an argument. Don’t let them wriggle away. Make them think.