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There are no coincidences or accidents. Everything happens for a reason. Everything is connected. The universe is sending you a message.

These are typical assertions from people who believe in synchronicity, a term coined by to describe seemingly meaningful coincidences supposedly not accounted for by random chance or natural causes. Jung, a believer in paranormal phenomena, thought such events are telling us something about the ways we’re all mysteriously connected to each other and to the universe at some metaphysical level.

Meant to Be

Consider an example: You live in Philadelphia but you’re sitting in a coffee shop in Brisbane during your first trip to Australia. Glancing through a rather old magazine, you see an ad for a movie. It’s the romantic film you took your ex-girlfriend (or ex-boyfriend) to on your first date, back in Philly some eight years ago. The movie wasn’t very popular, so it never appeared in the media after its brief run, but the two of you had often reminisced about it during your three-year relationship because that was when the chemistry first flowed between you. You’d broken up with her five years ago, mutually upset but on reasonably amicable terms, when you told her you just weren’t ready for a commitment after she’d patiently waited three years for you to make up your mind. You’d often regretted that decision, and wondered if an opportunity might arise to reconnect.

Now, reminded by the movie ad in the old magazine on the other side of the world, you wonder about the possibility of rekindling that relationship. At that very moment, to your astonishment, she walks right into the coffee shop. Neither of you had any idea the other was traveling in this country. She’s traveling alone, unattached. She’s both amazed and thrilled to see you. She tells you she’s been thinking a lot about you recently and in fact that very morning you had come up in a conversation with her best friend on the phone. The improbability of today’s encounter adds electricity to the excitement you both feel about the renewed prospects between you.

Destiny? What are the odds?

Hindsight

There are many cognitive biases that contribute to the unfounded eerie feeling of a seemingly improbable and meaningful coincidence. One of them, which we’ll consider here, is hindsight bias: you’re judging the probability of the event after the fact, pondering the odds backward. If you had specifically predicted in advance, prior to her walking into the coffee shop, that she would do so at that particular time, without any knowledge of her travel plans or any other conscious or awareness of information that might have significantly increased the likelihood of this encounter, then THAT would be an impressive coincidence. But without an a priori prediction, you have merely observed the probability of any very subjectively resonant coincidence occurring at any time, not the probability of that specific coincidence occurring at that particular time.

A Different Branch in the Range of Possible Scenarios

Rather than the event just described, let’s imagine a different scenario instead: Your ex never walks into that coffee shop, but shortly after returning home from your trip, you meet someone new. It happens while both of you are walking your dogs in a park and while, for the first time in a very long time, you’re very deep in thought reflecting on how you blew the chance to commit to that previous relationship five years ago. Your thoughts about your ex had been triggered in the park by searching on your phone for an email from a business associate. Your key-word search had instead pulled up an old email from your ex in which she had appealed to you to be decisive about where you saw your partnership going, or risk losing what you had invested together.

Just as you’re absorbed in your feelings of regret about the opportunity you had let slip away due to indecisiveness, and wondering if another long-term relationship opportunity like that will ever come along, your thoughts are interrupted by a friend in another city texting you a meme with the quote “Chance favors only the prepared mind.” Just at that moment, the friendly dog-walker initiates casual conversation with you. You’re immediately charmed by this stranger. You discover you have so much in common. You seize the opportunity: you arrange to meet again and hit it off really well.

Then you start . This time you play your cards right—struck by the strange timing of that first encounter; it’s like the universe is giving you a second chance. Within a couple of months, you’re pledging your commitment to a serious and fulfilling relationship. You go on to marry and, by all indications, you’re so well matched, it’s set to be a solid, lifelong union. It really feels like the universe intended for you to meet this person at just that right time of mental preparedness. Maybe the previous failed relationship was meant to be, to make you ready to meet your ultimate soulmate and seize the fleeting opportunity of that initial encounter in the park.

All the Things That Could Have Happened But Didn’t

When we look back and think an event was meant to be, we have mistakenly considered only the probability of that particular coincidence occurring at that particular time, not the probability of any possible seemingly meaningful coincidence occurring at any time.

The example of the dog park encounter didn’t have to involve another relationship scenario in order to demonstrate the possible coincidences that could have occurred instead of the Brisbane coffee shop encounter. The range of permutations of self-referent, subjectively emotionally meaningful events that could potentially have occurred, and that would have seemed just as eerie is endless. The probability of some kind of seemingly improbable coincidence occurring every once in a while is statistically very much higher than we realize.

The human tendency to believe that everything happens for a reason (and it’s all about me) is quite pervasive. There are evolutionary reasons for this human thought habit, and it is amplified in mental illness.

The Extreme Improbability of Your Birth

To understand how hindsight bias can skew us to think that events are highly improbable, consider the improbability of your very existence: It all began with your fertilization. What were the odds? Think about it. If that particular sperm, one among millions, hadn’t fertilized that particular egg on that particular occasion, you wouldn’t exist. If a different sperm from your father (even a split-second later) or a different egg from your mother (a month later) was fertilized, then your hypothetical would exist instead of you. You are absurdly improbable!

But wait. Think more carefully. It’s a little like pondering the probability that the telephone company would have assigned your particular ten-digit phone number to you. That number is uniquely associated with your now, after its assignment to you. But it’s obvious in this example that you’re asking this question backward, after-the-fact. The question about the probability of you being assigned that particular unique number could only have been meaningful if you’d framed the question prospectively, as a prediction: you’d have to first pick a number at random, before asking the telephone company to assign one to you. Then, without any foreknowledge of, or influence on, the telephone company’s operations, you could ponder the odds that the company would assign you the very number you’d already picked. Then see if they actually do.

Do You Really Think the Universe is Designed for You?

Viewing coincidences or " " as signs—a form of guidance from God or the Universe—may seem like a sweet and harmless belief until you consider that personal histories and societal histories are awash with countless examples of people validating their decisions or actions, many of them horrendous, through the interpretation of "signs." Kings frequently went to war after receiving such signs.

And what does such a belief imply about the multitude of unlucky people suffering cruel adversity? Is the universe conspiring malevolently to cause terrible harm to them?

Here’s a tip: write down your predictions every time you make one, and meticulously record both the hits and the misses. And be as meticulous as an experienced scientist in controlling for and excluding factors that could bias the outcome. Oh, and subject your methodology to the peer review of independent skeptical scientists who, lacking your subjective viewpoint, will more easily identify and pick apart the bias, confounding variables, and other methodological flaws that escaped your .

Once you understand the role of cognitive bias, emotion, and subjectivity in imbuing events with self-referent salience, you realize that the more eerie and spine-chilling a coincidence feels, the more skeptical we ought to be about our habit of thinking that the universe is intentionally designed for us.