I once answered an exam question about the borders of life. It may have been an undergraduate philosophy course final, or law school, I don’t remember which for sure. I wish I had a copy of the essay I wrote. A neighborhood social website conversation reminded me of this today. Somebody posted advice from a doctor about how to wash hands and clean surfaces to best avoid transmitting corona virus, which included the datum (from an MD, so of course true as “science”) that viruses are not alive.
Well, there’s a long and very interesting history of this issue. See, e.g., Scientific American, 2004.
The bottom line is, definitions and demarcations of life in terms of biology/chemistry/physics (let alone Western medicine) have some practical necessity and obvious uses, but they very quickly look arbitrary outside of their own limited contexts.
As I recall my essay answer to the exam question, it seems easiest to approach the question of what is alive on a purely experiential level. We all recognize outstanding human genius as strong evidence of life. The Beatles, Marylin Monroe, Einstein, Beethoven, Maimonides, Augustine, Sun Tzu... were proof that life is real. Life is certainly bright and distinguishable from pure solidity.
Then consider a level of just a bit less genius. Mario Cuomo, Anthony Fauci, Tom Zubik, Jitsy Wolf... these guys are certainly alive, with obvious influence and power way beyond what any inert object exerts.
Down the scale another step perhaps (apologies for any appearance of implied diminished value — just stand by, I’ll cure that shortly, I hope), we should consider retired uncles, circumstantially unemployed adults (there are suddenly a whole shitload of those!) and just ordinary people walking around or staying in their homes by order of the government, like the lady who forwarded the doctor’s advice about viruses this morning... these are all living human beings, unique and worthy of high respect. This is still easy enough to understand.
Below normal humans (again, bear with me) we relate to the disabled. Our ethics rightly demand that we acknowledge their fundamental humanity, but there is a long scale of disability from somebody who just has a touch of ADHD or depression, through the autism spectrum, to severe psychosis, Down’s syndrome and advanced Alzheimer’s dementia. Despite their humanity, these people do become less alive in a way, according to our honest experience.
Somewhere in the least fortunate depths of human disability, we may find ourselves embarrassed by our own higher affinity for nonhuman beings like our pets, or non-domestic animal species. Call of the Wild, Lassie, Black Velvet, Flipper and Old Yeller are not so fictional as to lack connection to honest emotions. I’ve known several Airedale terriers with whom I would rather hang out socially than a couple of my neighbors, not to mention members of my own family who spent excruciating years as hospitalized vegetables, (presumably, we hope for nobility’s sake) trying to die.
There’s a smooth transition from animals to plants, too. Coral looks entirely plant-like to me, but I know it’s part of the animal kingdom. Plants and animals are all alive, and we instinctively value them for that. I saw a Columbia cocaine smuggler shoot a beautiful dog for no good reason on the TV show “Narcos”, and it felt like a terrible crime. My son films ocean life for a not-for-profit, and to him it’s cruel whenever a fish in my saltwater aquarium dies.
Algae, and single cell plankton (are they plants or animals?) are clearly part of life. If we lose them, pretty soon nobody eats. We know we have to respect the Earth.
Bacteria are single cell life forms, too. They reproduce themselves asexually, by just dividing in half. We’d never say that they think — but lots of people wouldn’t believe my dogs think either. (And I know that’s wrong, at least as well as anyone knows what they even mean when they say “think”.)
Viruses have no cellular structure, but they do have DNA or RNA, and they can take over living cells, directing their activities and and using their structures and resources to replicate themselves. Viruses have certainly affected and contributed to the history and development of life on earth.
Other sub-cellular constituents like ribosomes, mitochondria and complex proteins are orders of magnitude larger and more interesting than simple molecules. However they are molecules nonetheless, they just have a lot more to do with life than simpler non-organic compounds.
The smaller the particle gets, the more mechanical it may seem all by itself. But this is only true if you don’t get all the way down. Is an electron a particle or a wave? Quarks have spin and personality, according to physicists. Quantum uncertainty can’t really be deciphered and at the fringes of physics we have theories that seem as spiritual as they are physical. Solidity may be an illusion, things can always come further apart.
If the world really boils down to mathematical equations and probabilities, that’s not so far from pure opinions or subjective viewpoints, and experientially perhaps we’ve come around in a full circle, back to aesthetics and the genius.
My point is that there’s no objective fine line anywhere on this entire route to divide, e.g., superhuman from human, from subhuman, from animal, from life form, from organic, from molecular, from mathematical, from aesthetic, from superhuman once again. When we talk about life, that’s not any scientific, physics/chemistry/biology issue: it’s a philosophical issue. Physics, chemistry, biology (let alone medicine), for all their practical value in our regular world, cannot even conclusively settle whether our novel coronavirus is alive or not. We tell ourselves we are fighting a war with it, but we don’t even know if it’s alive!
In the movie “Little Big Man” Dustin Hoffman’s character Jack Crabb was told by the Souix medicine man whom he called Grandfather about the essential difference between the “Human Beings” (Comanche Souix) and the white man:
To the Human Beings everything is alive. Rocks, trees, water, animals... they are all alive. To the white man everything is dead, even (in an incredulous tone) PEOPLE!
Psychiatrists are the ultimate white men in this time of viral catastrophe. If we are in a war, may the human beings win!