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In 1947, Claude Beck used the defibrillator to undo what was once deemed irreversible: the cessation of the human heart. Only a few years later, the first mass-produced mechanical ventilator began supporting inert bodies through heavy steel lungs. For the first time, the heart and the breath, those ancient signs of life, could be outsourced to mechanical devices—and seemingly overnight, the boundary between life and death shifted under our feet.
Today’s debates on standards of brain versus bodily death continue the dialog inaugurated by these apparatuses, but the conversation’s scope has grown as technical innovations create new limit cases to challenge our intuitions on life. As scientists sustained embryos in artificial wombs for increasing periods of time, stem cell research was forced to confront the ambiguity of when a human life, with its corollary rights, begins. More recently, digital tech—like artificial intelligence or its more experimental corollary, artificial life—has raised further questions as to whether inorganic beings might count among the court of the living.
At their core, these arguments express the fundamental difficulty of formulating any comprehensive definition of life. As Carol Cleland writes in The Quest for a Universal Theory of Life, “despite strenuous efforts over the past couple of hundred years, biologists have yet to come up with an empirically fruitful, truly general theory of familiar Earth life.” No matter which way we’ve tried to turn, we’ve encountered ruptures and revisions and counterexamples that obstruct our progress toward a universal definition. Despite this, we’ve continued to talk about “life” as if it were a discrete, agreed-on concept—a fixed point that we can mutually reference, even build our ethics and politics around. But the term’s vagueness has meant that most of the time, we’re talking past each other.
Some think that the solution is to keep drilling until we finally identify some bedrock definition that will satisfy everyone. There is, however, another way out of this labyrinth: We can abandon “life” as a universal, natural classification altogether. By ridding ourselves of life’s metaphysical baggage and the search for its “first principles,” we can circumvent these contradictions and open ourselves up to a broader array of possibilities.
In the West, we can trace most of our modern ideas of “life” back to Aristotle, the so-called father of biology. His De Anima constitutes the earliest attempts to realize a general principle of life, and the basic approach that he establishes still orients our theories today. Critically, it is also the source of many of the structural obstacles and paradoxes we face.
Consider the anthropocentrism that runs through Aristotle, inherited by those that followed. Whether it’s the soul, complexity, consciousness, or neuronal activity—whatever relevant criterion we’ve established as the central feature of life, humans have always seemed to have the most of it. This has unsurprisingly been leveraged to justify our dominion over the rest of the world, and has led us to sorely undervalue and underestimate the diversity of beings we coexist with.
More importantly, Aristotle’s search for a satisfactory principle of life—a “definition”—might have been misguided from the start. In After Life, the theorist Eugene Thacker traces the trajectory of this exploration and identifies a contradiction at the heart of it. There are, Thacker notes, two competing approaches that must be reconciled if one hopes to have a singular definition of life: that of the naturalist, who’s interested in “describing animal anatomy and physiology, and the vital processes of growth and decay,” and that of the metaphysicist, who wants to develop “fundamental metaphysical concepts concerning substance, accident, causality, form, and so on.” In the naturalist mode, Aristotle aims to dissect the life-processes of an organism, identifying the functional capacities that distinguish the living from the nonliving (like growth, regulation, and reproduction). As a metaphysicist, he aspires to peer beyond these particulars and understand how these capacities and traits come to be in the first place—to develop a principle that accounts for the existence of these features in some things but not others. Any suitable general definition must thus fulfill two disparate ends. It must be both descriptive (able to identify the features and processes essential to life) and explanatory (able to furnish a concept that explains what gives rise to these features and processes).
In order to satisfy the descriptive condition, life must be positioned as a trait immanent in any individual living thing, “inseparable from actual instances of life.” That is, life must be the kind of thing understood and defined by the qualities manifested by actual living organisms. A definition of life that existed outside of the particular—that was somehow agnostic to the ways in which life is realized (these “actual instances”)—would be void of substance. Defining life as something like the presence of an immaterial “soul,” for example, does little to help us meaningfully distinguish a stone from a tree by any observable traits. Life must be discoverable within the organism and its expressed properties if it’s to be capable of making a real distinction between the kinds of objects in the world.
At the same time, life must be seen as transcendent to these individual instances—not “determined or limited” by them—if it is to be explanatory and generalizable; it must designate something beyond the features of these living beings, encapsulating a more elemental quality giving rise to these traits. It would be ad hoc to assert that life is just a combination of characteristics like metabolism and stimuli-responsiveness, since that wouldn’t explain how these attributes arose. Not to mention that this functional, descriptive approach is ambiguous, since many non-living things express these traits (as Carl Sagan notes, candle flames could be said to have metabolism insofar as they maintain their shape by exchanging energy with their surroundings, and a car can be said to “eat, metabolize, excrete, breathe, move, and be responsive to external stimuli”). A metaphysically satisfying answer to “what is life” must illuminate the deeper relationships between these properties—revealing what gives rise to these processes and allowing us to distinguish when these attributes are representative of life and when they aren’t.
Yet these two things exist in tension with each other, making it difficult for any definition to achieve both ends. When observing an organism under a microscope, for instance, you might see biological processes hard at work, but there is nothing like “life itself”—some essence residing within the living thing, animating all these mechanisms—that you can point to. Meanwhile, transcendental concepts developed through armchair speculation float too high above the fray of life; when examined, they tend to be blurry, lacking “properties, attributes, or characteristics.” A gap between “life and the living” divides attempts at a grand unified theory, splitting metaphysical Life from biological lives. It either becomes so abstracted that it no longer has any explanatory power in the physical world (as happens in those quasi-theistic attempts to understand life as a “spirit” or a “vital force”), or it’s reduced down to an assembly of characteristics and processes lacking a unifying thread (as happens in a strictly physicalist approach that only attends to particulars like metabolism or genetic inheritance). A singular principle that retains both aspects—one capable of explaining the diverse mechanics of life without being reducible to them—remains elusive.
The field of astrobiology re-enacts this Life versus the living problematic on a cosmic scale. Astrobiologists looking to formulate a widely applicable definition to guide their search for extraterrestrial organisms must contend with the fact that all the creatures we’ve encountered so far likely stem from a common ancestor, leaving us functionally with a sample size of one when it comes to instances of life (what researchers refer to as the “N=1 problem”). This means that the shared features of us terrans—like thermodynamic regulation or the capacity for Darwinian evolution—might simply be an idiosyncrasy of life on Earth, sufficient but not necessary to Life broadly considered. As the synthetic biologist Steven Benner notes, this makes it difficult to derive a general definition that we could confidently apply to alien life—to instances of “life that we do not know”—from Earth life alone. Like Aristotle, astrobiologists encounter an impasse when they try to jump from the particular to the transcendent. Back down on earth, the problem of competing definitions haunts bioethical debates, where differences in the ways we think about death for sentient beings (such as a person) on the one hand and biological organisms (such as a human body) on the other have made it difficult to align on a unitary concept.
These complications have resulted in a growing push to abandon the search for a singular definition. As Cleland explains, definitions operate within the sphere of human, linguistic constructs, which is why they’re able to lay out such explicit fulfillment conditions. When we say that a “bachelor is an unmarried, human male” we’re not going out into the world and discovering something new about bachelors, but rather unpacking the socially-prescribed limits of the concept— the ways we’ve agreed to use the term. A scientist interested in the definition of life, however, isn’t so much interested in “an analysis of the contemporary human concept of life” (its social or semantic significance) as much as they are in understanding what life “truly is: what bacteria, slime molds, fungi, fish … and elephants all have in common.” It would therefore be a mistake to try to apply the neat framework of a definition to the project of empirical discovery, which looks to capture the messy affairs of the world in full. More bluntly, the philosopher of science Edouard Machery writes that it’s “no accident” that no consensus has emerged; rather, it’s a sign that the “project of defining life is either impossible or pointless.”
As we attempt to build a more equitable politics that extends past the human (toward the nonhuman animals, future generations, new technologies, and ecosystems that make up the tapestry of our world), what is needed is not another all-encompassing definition, but a “critique of life,” as Thacker phrases it—a radical reorientation that clears away the theoretical overgrowth and leaves us with space to cultivate something new.
The philosopher Thomas Nagel famously framed consciousness as existing in an object only if “there is something that it is like to be” that object. There’s certainly something that it’s like to be a human, so we uncontroversially ascribe consciousness to ourselves. The same goes for most animals. But what about an ant or a tree— or more radically, atoms and quarks? For most of modern history, broaching these latter possibilities could have gotten you laughed out of academia. Yet it’s an idea that people have been increasingly turning to in order to resolve some of the core problems plaguing the competing theories of consciousness. It’s a position known as panpsychism—or Integrated Information Theory—and it roughly holds that consciousness is a fundamental, rather than an emergent, aspect of existence.
The idea that everything is made up of “thinking stuff” might sound like a revelation conjured up in a hazy freshman dorm, but it’s a genuine response to a growing body of research. Centuries ago, Descartes argued that animals were mere mindless automata. Now we accept this view as a misguided relic of the past. Not so long ago we thought that plants couldn’t possibly have anything like a consciousness; yet research with slime molds, a brainless blob without a neuronal system, has revealed that they can detect objects at a distance and decide to grow toward them, even replicating highly-efficient structures like the Tokyo subway system. Pea plants can seemingly learn, and fungal connections between root systems (or the Wood Wide Web, as it’s often called) facilitate resource coordination and communication between trees. Even the stability of atoms has, as the analytic philosopher Galen Strawson writes, “given way to fields of energy, essentially active diaphanous process-stuff that— intuitively—seems far less unlike the process of consciousness.” There’s been a steady march toward more and more mind over the past century as we’ve looked more attentively at what’s around us, every particle teeming with feeling, experience, and life. Panpsychism seeks to take what we already know exists in us, and characterize it as a fundamental aspect of the universe.
On the other end, there are those exploring what life and existence might mean for immense systems. Eco-theorist Tim Morton attunes us to what they call “hyperobjects”: things so large that they defy our traditional ontologies (superorganisms like coral reefs, technological infrastructures like the internet, pandemics, climate, capitalism). To Morton, acknowledging these incomprehensibly large entities is crucial if we’re to have any hope of confronting the global issues facing us today. Similarly, the Gaia hypothesis—a theory developed by scientist James Lovelock and biologist Lynn Margulis that took the Earth as a living entity composed of both living and nonliving parts—is being reinterpreted and revived by some of its old opponents. One such former critic, the molecular biologist Ford Doolittle, writes that integrating this idea with more mainstream scientific understanding has political significance insofar as it can “encourage us to look at nature as a coherent whole, with an evolutionary trajectory that we can foster or deflect as we choose.”
No longer shackled to a singular standard for life, we become open to recognizing it in all its diverse potential forms. This isn’t a cold, dead universe, but rather one brimming with vibrant beings from the nanoscopic to the planetary, existences that we are both made up of and wrapped up in. There is a certain comfort that comes with this opening up. In Reasons and Persons, the late Derek Parfit made the case that what matters is not ultimately your life considered individually, but rather the dense knot of relations that unite us with our past selves and others. My body might die, but I could still live on in a meaningful sense through the memories, experiences, and relationships formed with those close to me. Upon coming to this realization, he says that the walls of the “glass tunnel” isolating him disappeared. “There is still a difference between my life and the lives of other people,” he writes, “but the difference is less. Other people are closer.” Deconstructing the narrow hegemony of Life builds on Parfit by further breaking down these differences between us and the world we inhabit—trading in our exceptionalism for camaraderie.
This shift could be applied in a number of ways. It has relevance in the field of medical ethics, for instance, where it can intervene in the ongoing debates around death first raised by our ventilators. The criterion of “brain death,” initially posited by a Harvard ad hoc committee in 1968, wasn’t meant to serve as a standardized definition of death, but rather “pragmatic guidance for what was ethically permissible for patients with irreversible coma” (when, for example, you could take them off life support or harvest their organs). Since then, however, there are many who have argued that brain death should simply mean death. The shift is subtle, but betrays the deeply rooted, implicit belief in one true definition—a definition that should be handed down to patients and families from on high by experts.
Yet the history of life as a concept reveals that we shouldn’t take this or any definition for granted. Accepting its constructedness encourages us to unpack and critically engage with it, and this criticism is welcome not least because, as bioethicist Alan Weisbard notes, “the people who have done the deep and conceptual thinking about brain death are people … who tremendously value their cognitive abilities.” What of the vast traditions that focus on embodied life? Dismissing these beliefs (which, unsurprisingly, often come from non-Western worldviews) outright would add to the list of marginalized concerns brushed off by the dominant establishment. That’s not to say that brain death doesn’t work for its purposes—as the ethics scholar David DeGrazia notes, it’s another point entirely to ask “whether we must wait for death before engaging in ‘death behaviors’”—but we have reason to be wary of making it the definition. Instead, we might explore how to better integrate factors like individual choice in the definition of death into our care systems. If life doesn’t have some universal, discoverable grounding, then we must be hypersensitive to the culture, people, and suppositions that contribute to any formulation.
This also opens us up to developing entirely new, expansive views of life that can help us recontextualize the value of the natural world around us. If rivers and forests and coral reefs are not only made up of living creatures, but are themselves alive, then it shifts how we think about the protections these systems should have. Constructing an oil pipeline through an ecosystem would be a moral question invoking something akin to bodily rights and autonomy, not a utilitarian calculation of potential risks, rewards, and ROI. The adoption of the Rights of Nature doctrine— wherein ecosystems are granted the legal protections of personhood—by countries like Ecuador are a fruitful step in this direction, and we should hope to see more governing bodies following suit.
A pluralist approach also helps set boundaries on how this fuzzy term is leveraged in discourse. The topic of “living” AI, for example, has attracted an outsize amount of attention lately in the wake of programs like ChatGPT and LaMDA. But once we stop thinking of life as some sublime, weighty, singular essence that sets us apart from the world, it becomes easier to see that this question isn’t as important as it might seem. After all, the interminable attempts at philosophizing going on in Silicon Valley have a way of distracting from the real issues regarding these technologies, like the fact that they’re telling people to kill themselves. Turning our focus away from life can be as instrumental to progress as recognizing it—a principle that rings particularly true in domains like reproductive rights, where “asking doctors ‘What is life?’ or ‘What is death?’ may miss the point,” as Sarah Varney reports for NPR.
Life will inevitably continue to play a central role in policy and culture. But ridding ourselves of blind commitments to a universal ideal equips us with an approach flexible enough to deal with the challenging ethical and technological issues ahead. The concepts we build and leverage can be pragmatically tailored to the subject at hand, free from the pressure of serving as some final say on the matter. Moreover, it ushers in a world that’s far more diverse and colorful than we could have imagined. Just as the Copernican shift made possible a universe far vaster and richer than one narrowly constrained by scholastic geocentrism, so too will this move away from our outdated, human-sized ideas of life. Only by ending life as we know it can we build a future worth living in.
