My own personal definition of life is the following, somewhat hand-wavy, theoretically weak, though pragmatically strong definition: Life is anything capable of sloppy self-replication in a sufficiently complex environment. Viruses are definitely alive. Something like Tierra [1], Avida[2], or modern variants[3] of mutating copying programs come close, giving rise to whole ecosystems of parasites and hosts and defense…
Counterpoint: If viruses are alive then anything can be alive, given that some machine exists which would make copies of it. ie. if there was a shower-caddy copying machine, then suddenly shower-caddies could be alive. In a world with a different life architecture, viruses would likely just be random an uninteresting molecules.
>ie. if there was a shower-caddy copying machine, then suddenly shower-caddies could be alive.
If the shower caddys underwent sloppy replication allowing for sufficient complexity to have ongoing evolution of their own copying mechanism, I see absolutely no problem with this at all. They will rapidly evolve to become much more conventionally life-like.
I find the notion that viruses aren't alive to be totally absurd. They replicate themselves, evolve continuously into an ever-branching tree of different niches, etc.
Is your objection that they don't have their own copying machinery?
Should mistle-toe not count as alive even though it depends on a tree to live? Hell, it appears it's even missing most of the genes necessary for it's mitochondria to produce ATP[1] so if it's somehow hijacking ATP production from the host tree, it clearly has no ability to reproduce on it's own. What about a human male? They have no replication ability without a female host "machine" to make copies of themselves. Are they therefore not alive? I think your objection rapidly descends into absurdity if you closely examine your definitions.
> In a world with a different life architecture, viruses would likely just be random an uninteresting molecules.
In such a world, a virus would not exist. In the same notion, in a world without sources of sugars, starches, and proteins, you would not exist. If you happened to blink into existence in this same hypothetical as a virus, you would be an equally uninteresting collection of molecules that would rapidly disappear. [1]https://www.quantamagazine.org/the-mystery-of-mistletoes-mis...