This holiday season has been the end of an extraordinarily exhausting, pedal-to-the-metal year. After the tsunami of papers to be graded, and urgent writing projects to be attended to and set aside, my philosopher spouse and I finally had the mental and emotional space to relax, hang out with each other, and indulge in the yearly ritual of binge-watching a TV series.  

This year, we chose HBO’s The Leftovers. The story concerns the sudden disappearance of two percent of the world’s population, and the struggles of those who remain—the “leftovers” of the series’ title—to make sense of and come to terms with what has happened. While watching it, my mind kept wandering back to traumatic events that took place in my own life and in the lives of my friends that we could never have anticipated: a serious automobile accident, the abrupt and savage destruction of a seemingly secure and loving relationship, an assault, a rape, the diagnosis of a terminal illness, the death of a dear friend. When such things happen, the regularities of life—the daily routines and expectations that cement our lives into a unity—seem to go up in smoke. Events like these can have destructive consequences far beyond what’s immediate. When what you thought was solid ground beneath your feet turns out to be quicksand, nothing, it seems, can be relied upon anymore. If this can happen, then anything can happen.

The Leftovers is such compelling viewing because it addresses a key feature of the human condition: the pervasive contingencies and uncertainties of life, the ongoing possibility of things happening to us that we can neither anticipate not encompass. One of the traditional roles of philosophy has been to help us to address and come to terms with these features of our existence. For instance, the Roman writer Boethius wrote his literary masterpiece Consolation of Philosophy while on death row. At the peak of a stellar career in philosophy and government, he was convicted on trumped-up charges of treason and sentenced to death. In his book, Boethius describes being visited by Lady Philosophy, who instructs him on life and fate. 

Much more recently, philosophers working in the existentialist tradition have made such matters part of their principal philosophical focus. But for the most part, these philosophers do not move me, either emotionally and intellectually. Instead, I turn to my intellectual hero David Hume for guidance. This might sound like a bizarre choice. Hume was an eighteenth-century empiricist, whose work is often seen as rather dry, analytical, and miles away from existential concerns. The part of his work that I think is most helpful in this connection is his analysis of what’s called the problem of induction.

The problem of induction is the problem of drawing conclusions about the future on the basis of what’s happened in the past. Here’s an example. I live in New England, a region that’s well known for its spectacular displays of fall foliage. It’s winter now, and the trees are bare, but I’m sure that once October rolls around again these same trees will be a riot of color. Why do I think so? It’s because every past fall has seen the New England leaves turn bright colors, and it’s because of this robust pattern that I’m confident that the same will occur next fall. In other words, I’ve reasoned my way from past observations to future ones. This sort of reasoning is called induction. 

Induction is central to the practice of science because scientists draw general conclusions—which include conclusions about unobserved cases—on the basis of a limited number of observations. The claim that a certain disease (say, plague) is caused by a certain bacterium (Yersinia pestis) is supposed to apply to every case of that disease that has ever existed or will ever exist, even though only a small fraction of them has ever been scientifically investigated. And it’s also an indispensable component of our everyday lives, which we conduct against a backdrop of taken-for-granted beliefs about life’s constants.

The problem of induction (or one might say, the problem with induction) is that there’s no logical basis for drawing conclusions about what will happen in the future on the basis of what’s happened in the past. Doing so rests on the assumption that that things will continue rolling out in just the same way as they did before. That’s at best a leap of faith and at worst an example of intellectual laziness. You might reply “I know that the leaves will turn orange next October because they’ve done so every October for as long as records have been kept!” But that wouldn’t address the problem, because the fact that something has been observed before—no matter how many times and how consistently—doesn’t say anything about what will happen in the future. And if you think that the laws of nature can underwrite inductive inferences, then think again. The laws of nature are just patterns that have held up until now. But that doesn’t guarantee that they’ll continue to hold  tomorrow. 

Hume helps us to recognize that although we wouldn’t be able to navigate through life without assuming that the patterns of the past will persist into the future, such assumptions are at best insecure. As I write these words, we are at the start of a new year and the dawn of a new decade. Many of us have made plans, formulated resolutions, and wondered what life will be throwing in our path, both as individuals and collectively. But Hume teaches us that even though life requires us to devise plans that are founded on what we believe will lie ahead, at any moment the unprecedented can erupt into our lives, and we can therefore never be certain of what the future holds.

Photo by Chris Lawton on Unsplash