How is life different than non-life?
Organisms are composed of atoms, and only of atoms. A carbon atom is not alive, not remotely. No atom is alive. Our organs are composed of cells, cells composed of molecules, and molecules composed of atoms. There is nothing else. We are composed of nothing but non-living atoms.
Still, we are alive. There is life. How can we understand it?
After we recognize that materially, we are composed of nothing but non-living things, we can begin to understand life in a variety of ways. But which way we choose to understand it is dependent on our habits of thought–our metaphysics, our traditions, our naive speculations. Philosophers have made a variety of sophisticated and subtle arguments for many of these ways, and they are worth studying if one finds it interesting and satisfying.
A wooden table is composed of a board and four legs, or some variation of that. And the legs and board are composed of molecules. The molecules are composed of atoms. Atoms are not tables. So the table is composed entirely of non-tables. There is nothing in the carbon atom within a wooden leg that resembles a table. Should we say that a table is not really a table?
There is no single right answer, because our answers can work at a variety of conceptual levels, and each level would allow for some answers better than others. In this sense, we can speak in otherwise confusing terms: this is both a table and a not-table.
But when we declare that a table is a table, we are dependent on more ideas and concepts than we would be if we simply declared that what appears as a table is simply an accumulation of particles that are mind recognizes as table. There is not inherent existence of the table. The termite burrowing through the table is not burrowing through a table–it is simply eating the wood that is there. The particles are not dependent on our mind–but the table is.
Except insofar as particles are mental constructs too: attempts by our mind to grasp and rationalize the building blocks of the material world. But the atoms are composed of protons, neutrons, and electrons, and there is nothing in a proton that resembles an atom…
So what, then, is life? We can choose to understand it in a variety of ways. And perhaps we strike closest to “Truth” if we train ourselves to see it in a variety of ways, rather than adhering to one, dogmatically, as if there were no other alternative. When I listen to people speak, we nearly always do so as if life were a thing, a separate category. If this is true, then it follows we should give greater consideration–as one of many possibilities–that insofar as we are “life,” we are more concepts than unique things.
But what sort of thing is life at the material level? Surely, it is more than a mere idea.
Life, I offer, should be thought of not as a thing, but a motion. And all its value is built on this peculiar motion. It is not necessarily the motion of our bodies, for different species have drastically different capacities for such motions, and many non-living things can move as much or more than most living things: the wind, ocean, and stars may appear life-like to some of us, and some say things like, “the wind is alive,” but this is merely metaphorical or forgets the wonder of life. Life’s peculiar and special movement is in our interiors, in the unimaginable diversity and complexity of billions or trillions of microscopic movements, overwhelmingly in harmony.
To open not just one’s heart, nor just one’s mind, nor just one’s intuition–however those are understood–but the whole of one’s self and attend to the unimaginable flux of the movements beneath one’s skin–and the skin itself–this is to understand what life is. It is not a distinct thing. If I sit in my room all by myself, I am different from all these things around me not because my atoms are special or that my thing-ness is inherently privileged or containing some special moral status. My body is unique and separate because of these material motions–the billions of forces within my cells and bloodstreams, slowly pushing around nutrients, splitting and cleaning, pumping mindlessly away. This is the beauty of life: not something that is visible on the surface, not something that is easily grasped by a concept, but in the ocean-depth of small movements.
Concluding Proposition: “Life” is a concept used to designate a particular sort of process–a large set of processes–by inorganic, non-living matter. The processes are huge in number, and tiny: at a low level, it is composed of cells moving nutrients, splitting, transferring other material, processing resources, or transporting electro-chemical signals.
This was a brief exposition, not a definition. One of the requirements for a adequate definition is that both includes the term being defined, and excludes everything else, so that the definition points only to one thing.