In the 1960s, a climatologist named Edward Lorenz worked on developing a set of difference equations to study weather forecasting. This type of equation is used to model what happens to a system as a function of time: a variable is traced from the beginning (time = 0) in repeating steps (iterations) at each time (t = 1,2,3, etc.).

Lorenz found logical, expected results when a constant used in the equation was set at a particular level, but at higher values, the results showed a strange, oscillating pattern with time. The higher the value of the constant, the more irregular the cycles became, and at a certain point, they lost all semblance of regularity and fluctuated wildly in a chaotic fashion. Chaos theory was born.

Lorenz also found that when he rounded out the value used for the starting condition, using 5.21 instead of 5.21332, for example, the solutions over time showed a completely different pattern. This extreme dependence on initial conditions is sometimes called the “butterfly effect,” after the idea that a butterfly flapping its wings in China could create a storm in Texas a few days later. Chaotic dynamics occur in many, if not all, complex dynamic systems, like the stock market, national economies, heart physiology, and so on. And, of course, the most complex of all systems, human society, is totally ruled by chaos theory. I call this the “human effect,” and I believe it has some interesting philosophical implications.

Humans have been compared to a collection of gas molecules randomly colliding and going in unpredictable ways but en masse forming a highly deterministic and predictable system. But gas molecules make no choices; their individual behavior is truly random. Ours is not, which is what makes history so fascinating.

It’s entirely rational to propose that everything any of us do or say can have enormous effects on the state of the world. If I decide to stop during a walk and look into the window of a store, I will arrive at the bookstore five minutes later than I would have if I hadn’t stopped. That means I will enter the store just as another customer is leaving. I bump into him, we both apologize, he stops to pick up the books he dropped, I help him, we exchange a few words, and he goes on his way. That 45-second delay makes him too late to flag the taxi he would otherwise have gotten, and he needs to wait a good 15 minutes before he gives up on finding a taxi and calls Uber. The Uber driver picks him up. If the man had found the cab that I made him miss, the Uber driver would have picked up a woman a few blocks away. But since he didn’t, the woman gets into another Uber and finds that the driver looks familiar. It is in fact a man she knew in college, and after some conversation, they remember each other. They exchange numbers, meet a few days later, begin dating, fall in love, get married, and have children. Their children grow up, and the oldest becomes a scientist and discovers a cure for a disease. So the lives of thousands of people are saved by the child of the woman who took a different Uber because the man I bumped into was a few seconds later than he would have been if I hadn’t paused to look at the store window.

I just made that fantasy up, but such things happen all the time, and with some thought and research, examples are easy to find. The idea of the human effect is wonderfully illustrated in the film It’s a Wonderful Life. In the film, the existence or non existence of a single individual has major, unpredictable, and irreversible effects on the fortunes and character of a small town. The story makes us think about the reality that we are all critical to the reality of everyone else.

Humanity is a huge system. And everyone who is part of that system (which is everyone) has a role in what happens next. What this means is that nothing we do or say is ever lost, because the effects or ripples of our actions continuously rebound throughout history. I know that sounds silly. Imagine the millions and millions of people who have ever lived, and all the words and actions of all those people, all but the tiniest fraction of which are lost forever to our knowledge. But that is where my faith comes in. I don’t think they are lost.

All human lives are important, valuable, and (in my own religious view) holy. So choose what you do and say wisely, my friends. My life depends on it.