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Prions are cool, but they aren't self replicating.

They can convert existing proteins into more prions, but they can't make the proteins in the first place.

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That definition doesn't work I think. After all, viruses can't make nucleic acids, but they can repurpose them to self replicate. Humans self replicate but need vitamins and essential amino acids they we can't make. Whether it's prions, viruses, or humans, we're all just taking available resources and turning them into us

I'll grant that there is a continuum, but humans needing to get something clearly inorganic like copper from the environment (or an organic, but clearly non living chemical like and amino acid) is different than a prion needing a pre-made copy of itself to convert into more prions.

Prions are really enzymes that catalyse missfolding of other proteins.

In some sense no living thing is really autonomous, since energy can't be made and must be acquired from outside. But if we are defining life, I'd say the two main qualities would be a self contained vessel carrying around the machinery to eat and replicate.

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The debate over whether things like viruses are alive is still active, but it's pretty much consensus that the answer doesn't really matter.

The idea of a replicative system is much more significant and defined. Once you have replication you can have selection and therefore evolution. The "origin of life" probably wasn't some seminal moment of creation, it was one particular increase in complexity chosen by our definition. If you want a seminal moment, it was the formation of whatever replicative unit is ancestral, whether that replicative unit was Adam or an RNA-dependent-RNA-polymerase.

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One of the reasons I reject a view of the world that combines scientific naturalism with evolutionary theories of the development of not merely human line, but all life, is precisely because it views the difference between human life and non-human life as merely a matter of degree, and in fact views the difference between life and non-life as merely a matter of degree. In both cases, I think a binary is essential.

If the only difference between human life and non-human life is a matter of degree of complexity, then you don't really get human dignity, you don't really get a hard line between the human and the non-human. If this is true, there us no principled reason why we have moral responsibilities to infants that we don't have to, say, dogs. But we do have such moral responsibility. There is human dignity, a special human value.

You say that as if many people don't treat dogs better than humans.

There has to be a definition of an organism as a functional unit. Otherwise it's the problem of the many:
https://plato.stanford.edu/entries/problem-of-many/

Of course the defining an organization as something different than the sum of its parts leads to other problems like dualism.

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other problems like dualism.

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The truth is never a problem!

AstroAg17 said:

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That seems to me like starting with a conclusion and letting it define "life" to you.

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I start with what it most obvious to me, and try and get my other beliefs consistent with those other beliefs that are most obvious. That human dignity exists. That we have moral obligations to humans that we don't have to non-humans. Those are two examples of beliefs that I use as starting points.