What Makes Living Things Different?

A living thing is never simply there. A bacterium, a tree, or a human being has to keep itself going through processes that continually produce and repair the organization that makes it a living system. If those processes stop, the organism ceases to be alive. This rather obvious fact opens onto a surprisingly difficult question: what follows from having to continually make and maintain yourself?

In the earlier readings, we introduced the idea of autopoiesis to describe this self-producing and self-maintaining organization. We also saw that this does not make a living thing independent of its surroundings. Living systems maintain themselves through ongoing relations with a world that supplies matter, energy, and the conditions under which life is possible. The interesting form of autonomy here is the ability of a living system to maintain its own organization while remaining deeply dependent on relations that extend beyond it.

Many of the usual ways of separating living things from machines are becoming less convincing. Machines can respond to changing conditions, adapt their behavior, pursue goals, and operate for long periods without continuous external control. Increasingly, they can even modify aspects of their own behavior. So responsiveness, flexibility, or functional autonomy cannot by themselves tell us what is distinctive about living things.

The deeper question is what the activity of the system is for. In a living system, activity participates in maintaining the organization that makes further activity possible. What happens to the organism can therefore bear on its own continuation. Some conditions sustain its way of life and others undermine it. This is the beginning of an important asymmetry between living and nonliving systems: things can go better or worse for a living thing in relation to the maintenance of its own organization.

These are the questions pursued by the biological strand of enactivism: how does having to maintain itself shape what a living thing can do, and what can matter to it?

Autopoiesis: How Living Things Create Themselves

A cell has a boundary, but that boundary is not simply a container for the machinery of life. The membrane is itself produced and maintained through the activity going on within the cell, while that activity depends on the continued existence of the membrane. The same circularity runs through the rest of cellular life: the processes that keep the cell going depend on components that those very processes continually produce and replace.

This is the idea Maturana and Varela were trying to capture with the term autopoiesis, literally self-production (Maturana & Varela, 1980). There is no production line outside the cell assembling it: cells make themselves. More precisely, a cell continually makes the components and relations through which it continues to exist as a cell. It doesn’t create the atoms it is made of, and it takes in matter and energy from outside, but those resources do not arrive with instructions for how to make a living system. They are taken up within an organization that is already actively maintaining itself.

Maturana and Varela proposed autopoiesis as the organization characteristic of living systems. We do not need to treat that proposal as the final biological definition of life to ask what follows from it. Being alive involves more than possessing a particular collection of parts. The parts participate in processes that continually regenerate the system that makes those processes possible.

Enactivists distinguish this organization from a system’s structure, the particular components that realize it at a given time. A cell’s structure changes continuously even while its autopoietic organization persists.

A living thing is therefore not a fixed collection of material. Much of its material comes and goes. What persists is a way of organizing ongoing activity through which the system keeps becoming the living thing that it is.

Living Agency and the Achievement of Self-Maintenance

A rock can persist for millions of years without doing anything to remain a rock. A bacterium cannot. Even when nothing dramatic seems to be happening, the bacterium is continually carrying out the processes through which it remains alive. Its existence is an activity. The philosopher Hans Jonas (1966) put this by saying that an organism’s being is its own doing.

Feeding, moving, regulating temperature, repairing damage, and responding to threats all take place within a larger condition: the living system must continue to maintain the organization through which it exists at all. A failure here is different from failing to reach a destination or solve a problem. If self-maintenance fails completely, the system ceases to be a living system.

We often recognize agency from what something does: it moves toward a goal, selects among alternatives, or changes its behavior when circumstances change. On those criteria, there is no reason to reserve agency for living things. Machines can behave in all of these ways. But living activity has another dimension. What an organism does takes place against the continuing possibility that its own way of life can be sustained or undermined (Barandiaran et al., 2009).

Consider a bacterium moving in relation to sugar. We can describe the chemistry and movement without saying that the bacterium consciously wants anything. But sugar is not simply another physical feature of the surroundings. Because of the way the bacterium is organized, encountering sugar can contribute to processes through which it continues to live. On the enactive account developed here, this is the sense in which sugar can be said to matter to the bacterium in a way that the bacterium does not matter to the sugar (Thompson & Stapleton, 2009).

Organism and environment affect one another, but they do not stand in the same relation to what happens. The bacterium can flourish, struggle, or die. Nothing comparable is at stake for the sugar molecule. The organism remains dependent on its surroundings, but it is a distinctive participant in that relation because its own continued organization is at stake.

Perspectives and Norms

Once some encounters can sustain a living system and others can undermine it, the surroundings are no longer equivalent from the standpoint of that system. Sugar can be food for a bacterium. Light can support the activity of a plant. A sudden change in temperature can be tolerable for one organism and destructive for another. These relations are not properties of sugar, light, or temperature alone. They depend on the organization and way of life of the organism involved.

In this sense, a living thing has a perspective. This need not involve conscious experience or an ability to reflect on the world: the organism encounters its surroundings as the particular kind of living system that it is. What can affect it, what it can respond to, and what can support or threaten its continued way of life all depend on its structure and history.

Enactivist accounts often connect this idea to precariousness. A living thing does not simply possess an organization once and for all. That organization has to be continually maintained under conditions in which maintenance can fail. Because of this, there can be better and worse outcomes for the organism. A bacterium can fail to find nutrients. A plant can fail to obtain enough light or water. An animal can be injured or starve. None of this requires the organism to represent these outcomes consciously as good or bad. The possibility of success and failure is built into the fact that its continued organization is at stake. As discussed in Embodiment and Enactivism, Di Paolo (2005) distinguishes this precariousness from adaptivity: the capacity to regulate activity in relation to conditions of viability. That distinction is important when moving from an account of self-maintenance to one of sense-making.

Food, shelter and danger are relations that arise through the meeting of a particular organism with particular features of the world. What counts as food for one organism may be irrelevant or poisonous to another. What counts as a signal, affordance, or threat likewise depends on the kind of system encountering it.

Other living things are part of these environments too. A flower and a bee can each become significant to the other because of how their respective ways of life have developed. The flower is not simply an object in the bee’s surroundings, and the bee is not simply an external influence on the flower. Their relations have histories, and those histories can become part of the conditions through which each continues to live. Living autonomy produces organisms whose distinct perspectives are formed and maintained through relations with a world that includes other living beings.

Development as Inherited Achievement

A living thing not only has to maintain itself. It also has to become the kind of living thing that can do so. Every organism begins in one condition and undergoes enormous structural change while somehow remaining part of a continuous living process. Development therefore presents a version of the same puzzle: how can a living system change so much while maintaining the organization through which it continues to exist?

Nonliving systems can have histories too. Hurricanes form, crystals grow, and sand dunes change shape over time. What happens next can depend on what has already happened. But a developing organism is part of a lineage in a different sense. It begins with resources, structures, and relations that are themselves products of previous living systems, and through development it reconstructs a viable way of life.

Developmental systems theorists describe inheritance in terms of the reconstruction of a matrix of developmental resources across generations, rather than the transmission of a finished plan (Griffiths & Hochman, 2015). Development depends on genetic material, cellular organization, nutrients, physical conditions, and, in many species, relations with parents, other organisms, and culturally organized environments. None of these resources by itself specifies the finished organism. What develops emerges through their ongoing coordination.

Members of a species usually develop recognizable forms and ways of life, yet no two developmental histories are identical. Organisms can compensate for some disturbances, reorganize in response to changing conditions, and arrive at viable outcomes through somewhat different developmental routes. Other perturbations exceed what the developing system can accommodate. Development is neither the execution of a fixed program nor unrestricted flexibility, but the construction of a living organization under particular inherited and current conditions.

Seen this way, every developing organism is carrying forward an achievement it did not begin. The capacity to build and maintain a viable organism has a history extending far beyond the individual life. Each generation begins with the products of previous generations and, through its own activity, constructs another living individual. What is inherited is entry into a developmental process through which a way of life can be made again.

The Uniqueness of Living Autonomy

So what makes living things different? Not simply movement, responsiveness, flexibility, or even the ability to pursue goals. Nonliving systems can show some or all of these properties. Nor is the difference just that living things have bodies. The more fundamental point is that a living system participates in producing and maintaining the organization through which it continues to exist.

Because living organization has to be continually achieved, the organism can succeed or fail in maintaining its way of life. Because it can succeed or fail, some encounters can sustain it and others can threaten it. And because what sustains or threatens an organism depends on the kind of organism it is, living things encounter the world from particular perspectives. On this enactive view, agency, normativity, and meaning are not later additions to life but grow out of the conditions of living itself.

Artificial systems make this easier to see because they increasingly display behaviors that once seemed distinctive of organisms. They can act autonomously in a functional sense, adapt to changing conditions, and pursue goals with considerable flexibility. Present artificial systems, however, do not maintain themselves through the same kind of self-producing organization. Their continued existence is not what establishes the significance of the goals they pursue. One way to see the difference is to ask what happens when a system stops acting. In a living cell, the structures that shape its activity are continually breaking down and have to be rebuilt by that same activity. Without a continuing supply of energy, the cell cannot keep rebuilding them. A robot’s circuits can remain intact while it is switched off; they do not have to be rebuilt by the activity they support (Nave, 2026). Whether some very different artificial system could ever develop an organization comparable to living things remains an open question. But sophisticated behavior alone would not be enough to show that it had done so.

No organism invents living from scratch. Every bacterium, tree, animal, and human begins within an unbroken history of living systems that have managed, generation after generation, to construct and maintain viable forms of life. The individual organism is new, but the achievement it carries forward is ancient.

References

Maturana, H. R., & Varela, F. J. (1980). Autopoiesis and cognition: The realization of the living. D. Reidel. https://doi.org/10.1007/978-94-009-8947-4

Di Paolo, E. A. (2005). Autopoiesis, adaptivity, teleology, agency. Phenomenology and the Cognitive Sciences, 4(4), 429–452. https://doi.org/10.1007/s11097-005-9002-y

Thompson, E., & Stapleton, M. (2009). Making sense of sense-making: Reflections on enactive and extended mind theories. Topoi, 28(1), 23–30. https://doi.org/10.1007/s11245-008-9043-2

Barandiaran, X. E., Di Paolo, E. A., & Rohde, M. (2009). Defining agency: Individuality, normativity, asymmetry, and spatio-temporality in action. Adaptive Behavior, 17(5), 367–386. https://doi.org/10.1177/1059712309343819

Jonas, H. (1966). The phenomenon of life: Toward a philosophical biology. Harper & Row.

Griffiths, P. E., & Hochman, A. (2015). Developmental systems theory. In H. Kehrer-Sawatzki (Ed.), eLS (pp. 1–7). John Wiley & Sons. https://doi.org/10.1002/9780470015902.a0003452.pub2

Nave, K. (2026). Beyond control: Finding the purpose of enactive cognitive science. Adaptive Behavior, 34(4–5), 273–293. https://doi.org/10.1177/10597123261435796