Chance is one thing, necessity another. That’s what they say.

Right?

Chance is what happens for no reason. It just happens to happen. It’s happenstance. Coincidence.

Necessity happens for a reason. It’s cause and effect. It’s consequence.

But what if these distinctions really don’t hold up?

What if chance and necessity aren’t that different? What if they are so intimately knotted we can’t undo them?

What if—yikes—what if they’re just about the same thing?

When I look at my children, all these questions come bubbling up. I think: How’d they get here? It seems impossible, a miracle. But I know the story, and I start retelling it in my head: My wife and I met… but first her parents and my parents had to meet… and their parents…

Many of the things we think are coincidences aren’t that coincidental. My friend and favorite mathematician, John Allen Paulos of Temple University has written this great book called Innumeracy, in which he tells us that many of the things we think are just amazing coincidences aren’t all that.

If there are 23 people in a room, chosen from all the world’s people absolutely at random, what is the probability that two of them have the same birthday? One chance in two. It’s not an amazing coincidence but actually pretty likely. How likely is it that you will have a dream that predicts the future? In the long run, pretty good.

Consider that person sitting next to you on an airplane. You get to talking, and soon discover that you know someone in common—a cousin, a high school chum. Gosh, what are the chances of that? you say. Well, the chances turn out to be pretty good. Remember the old six-degrees-of-separation rule: If you play human relations out to six degrees, as in a friend of a friend of a friend of a friend of a friend of a friend, almost everyone in the world is connected to everyone else in some fashion.

So what we sometimes think of as wild, could-never-happen-in-a-million-years, wacky, how-the-heck-about-that chance… dumb, crazy luck… really isn’t. It’s just that we can never know all the information. We can’t know all the relationships our friends, cousins, and old high school pals will have in their lives. They fan out, meet tons of people, and someday we may land next to one of them on a plane. We don’t know all the connections and never can—so when we brush up against them, it seems like chance.

Wow: We can never know the full significance of anything we do, going either backward or forward. Wow wow wow! Hilarious… and paralyzing.

Does it work the other way? Can necessity ever involve chance?

In a way, all of it does.

As the Polish fantasy master Stanislaw Lem once wrote, necessity runs on chance. What we call necessity or consequence is only what happens in front of our noses. And that’s only the end of a long chain of events millions of years long. And in that chain is a lot of ko-inky-dink.

Does that sound nuts? Ask yourself this question: What are the chances of me existing?

(Let’s just assume I do exist. I’m too tired to argue about it.)

The chain of cause and effect seems pretty tight. My mom was a nurse in the same hospital in which my dad was a doctor. They were both Irish, Catholic and middle-class. They had a lot in common. My dad was not the handsomest guy in the hospital, said my mom, but she liked him anyway. They had a lot in common. It fits. There’s a lot of necessity in there. It doesn’t seem very random. Neither does the way my grandparents met, or their parents.

But that only takes me back about 120 years.

Go further back than that, and I lose the chain. Go back 1,000 years, and… well, something happened, but I don’t know what. Let’s say, oh, the Vikings invaded somewhere, and Erik the Pigfaced impregnated Eleanor of Ongeplatchkit. Had the Vikings not invaded, Erik and Eleanor would never have met. Eleanor might have had another, let’s say, impregnator somewhere and have given rise to somebody else, but the result 1,000 years later wouldn’t have been moi.

Chance is all bound up in history. I once tried to figure out all the huge events in history that had to have happened for me to be the me I is. Here’s a few on the list: The Viking invasions of Ireland (Eric and Eleanor!); the Norman invasion of England; the English settlement of the Eastern half of the American continent; the Irish Potato Famine. It’s cool to be connected!

Lem has a story that traces a person’s existence all the way back to a chance union between two primates next to a eucalyptus tree 350,000 years ago. If that hadn’t happened, the long chain of events that led to this man’s existence would not have started. And he wouldn’t be.

We are, in other words, a thermodynamic impossibility. The chances against us existing are just about infinite. EACH man is, thus, the first prize in a lottery, as it were—in the kind of lottery, moreover, where the winning ticket is a teragigamegamulticentillion-to-one shot, Lem writes. It’s not that we shouldn’t exist. It’s that no one, even if they had all the information, could have predicted you.

So why don’t we feel unlikely? Well, because, if you lose the lottery, you don’t exist. To the tune of Auld Lang Syne: We’re here because we’re here because we’re here because we’re here.

The other reason is that we know so much about our lives, so intimately. Even if these things are chance, they seem necessary to us. They are our nearest causes and effects. It a terrific, huge accident that I am speaking English to you. Could have been Spanish or French, or, if the indigenous peoples had technology, Algonquin.

Then again, I was born of English-speaking Americans in the United States in 1953. I’m sorry, but I was going to grow up speaking English.

Hilarious and wonderful. Chance has a huge role in what we call necessity, and necessity a huge role in we call chance. My mom and dad did meet by a degree of chance, but it was a very narrowed, tempered kind of chance. A lot of history brought them together.

When I look at my children, the force of all this really smacks me. I think of them as improvements—not of my wife, no, but certainly of me. I know much more about what brought them together than they do. Chance and necessity did their most elegant dance in bringing my wife and me together.

On the other hand, my wife and I had a lot in common. That cuts down the range of chance right there. Character is fate: the way you are means you’ll do and be certain things—your character really does help direct the things that happen to you. Both my wife and I were raised Catholic. Both from big families. Both writers. Both going to Stanford. These commonalities, which we couldn’t have known about, may have helped draw her to me and me to her.

I’m sure you’ve done this: replayed the film of your life but changed a crucial event, undoing all the rest. What if I had never met my wife? It leaves me lost, terrified, in a universe I don’t recognize. I shiver in the knowledge of how close it came to being otherwise.

It also reminds us of the profound consequences of seemingly trivial acts. You turn right and are just in time to save Mother Teresa from the onrushing school bus. Turn left, and she gets flattened. Poor Mother T.

I once had a conversation with a man I knew. I enjoyed it but was unaware of any significance beyond a nice talk between friends. How was I to know that years later, he’d go out, convert, and become a lay missionary? Years still later, he told me that conversation had been a turning point.

A nice man once wrote a very brief letter to someone else. He probably didn’t think too much of it at the time. But had he not dashed off those few lines, I would not (a) have gone to graduate school; (b) become a professor; (c) married the woman I married; (d) had the family I had. Yours truly!

Tiny acts, biiiiig consequences. Makes you tremblingly afraid to do anything at all.

Or maybe, it should make us intent and reverent about our lives. We literally can never know when the merest, half-thought-out word or caress might shape someone else’s life, might be the difference. No, I know: people can’t live like that. It’s hard to both walk and think about walking; better just walk. But at least it suggests what the truly mindful life would be: accepting that each thing we do could help create lives unknown, reverberate infinitesimally for millennia.

As goals go, that’s not bad: to perform each act, each thought, in full understanding that it could be the Big Bang, when all fates were started, all fates sealed, when all chains of cause and effect started paying out in the directions they took, the point from which inevitability and chance really were the same. Wow. Wow wow wow.