As someone who has made it far enough into your day to turn on your computer and start reading this blog post, I doubt that you are harboring many doubts about whether or not you are alive, let alone whether life exists at all. It might surprise you to know that this exact worry was aired in a recent op-ed by Ferris Jabr, an editor for Scientific American. He boldly claims that nothing is truly alive and, what’s more, that this knowledge is “liberating.”
On the surface, life seems like one of the most obvious parts of nature to understand. The squirrel runs, the rock doesn’t. The seed sprouts and grows into a full blown tree, the log just sits there. Some things move and grow and reproduce of their own accord, other things need a good shove to get them going. The difficulty, as always, is in the details. Growing crystals, self-replicating molecules and parasitic viruses seem to mimic some of the powers we attribute to life, and provide counter-examples that make the definition of life more difficult for biologists to nail down.
Jabr’s revelation is that we need not be worried about the definition of life, because life is merely a mental construct anyways—there is nothing there to define. He argues that because there is no identifiable property or set of properties that scientists have been able to agree upon as the defining aspect of life, it simply is not there. Life is a “pure concept” that can be useful at times, but can just as easily be set aside. Everything that exists is really just a particular arrangement of fundamental particles, and we can find some of the features of life at many different levels of these arrangements from chemicals to whole biospheres. Life just becomes a useful way of labelling certain kinds of complexity we encounter in the real world and, unbound by a hard and fast definition, we are free to use it as we see fit.
Needless to say, there are a whole host of objections to Jabr’s proposal—scientific, philosophical, and theological. In fact, it’s a bit hard to decide where exactly to begin. One could argue for a robust definition of life as an internal principle of movement, object to Jabr’s implicit reductionism that assumes we can simply explain everything as collections of molecules, or present the whole host of ethical and legal ramifications to trivializing the concept of life.
Here, I simply want to link Jabr’s argument to a number of other skeptical arguments that seek to overturn common sense ideas in the name of science—and argue we’re better off for it. It’s an undeniable fact that modern science, particularly since the beginning of the twentieth century, has revealed that the world we live in is more complicated, wonderful, and at times bizarre than people ever expected. Nevertheless, the fact that we now take for granted almost unimaginable concepts like wave-particle duality and curved spacetime does not mean that the purpose or goal of science is to come up with weird ideas and to overturn our natural expectations. Scientific investigation of the very large and the very small did not reveal that our everyday assumptions completely fail. It clarified the bounds in which our everyday assumptions actually work, namely everyday applications.
Skeptics like to claim that a single difficult case can invalidate our preconceived notions, no matter how much previous experience and reasoning they are based on. Yet our understanding of the world and of nature, properly considered, need not be some well-constructed but fragile house of cards that cannot bear even the slightest jostle. Aristotle had a helpfully robust view of what it meant for something to be natural, namely that it happened “always or for the most part.” This is not simply a premodern “fudge factor,” but a deep insight into the fact that nature is at once usually reliable and a bit unpredictable, and this particular balance of consistency and fallibility allows for the beautiful order amongst all of its pieces.
While Aristotle applied the principle to understanding natural processes, in an analogous way we can apply it to our definitions and reasoning about those processes. Life is “always or for the most part” easily identifiable. The fact that there are inanimate substances that seem to mimic aspects of life need not destroy our confidence in the fact that there really is a difference between living and non-living. We should not look at difficult cases with fear for the possibility of life, but embrace them as a fascinating opportunity to work out the bounds of our understanding of life.
A full response to Jabr and his argument would need to actually address his concerns about the definition of life and the difficult cases he brings up. While I think just such a response is possible, it is worth noting that the skeptical perspective—that a few counter examples is all it takes to overturn consistent and well supported ideas about nature—has a tendency to create worries no one ever really had, and to solve them in a way no one really appreciates. A healthy view of natural philosophy can accept the corrective and enlightening role of difficult cases without fearing that it will lose the very foundation it was built upon in the process.
Image: Jan Verkolje, Portrait of Anthony van Leeuwenhoek (1632-1723)