I thought the definition of life was a matter philosophical, not scientific, debate. How does one "find evidence" to support an open philosophical argument?
If you ignore the title, the article is interesting.
They identified 66 "types" of proteins that are unique to virus and are not presents in bacteria, archea or eukaryotes (animals, plant, fungi, ...).
They use 66 "types" of proteins to classify some of the virus, make a phylogenic tree, and see evolution in the tree. This evolution is independent of the evolution of the cells.
So they propose that this new phylogenic tree must be included in THE phylogenic tree along with the trees of the bacteria, archea or eukaryotes (animals, plant, fungi, ...).
The non-virus tress are connected, I'm not sure how this will connect this new tree.
I didn't look at the details and I'm not a biologist, but this sounds like good science. (I guess it's overhyped as usual, and I'd wait five year just to be sure, but I think this has only the standard overhype in a press release.)
Does it mind that the viruses are alive? Cows are alive, rocks are not alive. IIRC trees were classified as not alive until a few thousands years ago. Life is an arbitrary label for a set of atoms, it's useful but the threshold is arbitrary.
I guess they did this study because the usual way of classifying life forms, dna analysis, doesn't work for viruses. But how can we know that older life forms didn't have these proteins? Complex cells can have lines that die out without extincting the order. Viruses may be too simple for that; so they retain all the older parts?
The problem is really a semantic one, I'd say. The issue is what is defined as "a virus". Typically a virion is used as the canonical representation of a virus, but this is no more accurate than calling an egg a chicken. This is merely an infectious particle, one part of the viral lifecycle. Properly, the virus when it is operating after infecting a host is just as much "the virus", and in that phase is very much easier to see as alive.
Nothing specific to the article here, but in general I believe philosophical question tends to be explain or made obsolete by scientific discovery rather than philosophy itself. Look at the discussion on "life substance" (I forgot the term) before we learn how to synthesize organic compound as an example. Otherwise, the concurrent philosophical text on conscious and intelligence would be another case where answer would likely be explain by science.
This is a common view amongst people who have never studied philosophy. Everyone is engaged in philosophy, including scientists themselves, and mostly poorly.
Scientists in considering what data signifies life are themselves taking as given some concept 'life' - ie. their first step is philosophical (as ever). You may say whatever a decision a scientist makes on concepts such as these is obviously the best - but then history would show you totally incorrect.
It is possible to refine the method of judging the best concepts, and of refining the questions which lead to these judgements, and of the method of making the best deicisons with respect to them. This task is philosophy. And "incorrect philosophy" of the past such as the vital force was a philosophy of an incorrect science - not somehow a "pure philosophy" that had gone wrong.
A philosophy of a better science produces a better philosophy (and a better science).
> This is a common view amongst people who have never studied philosophy
I really should take offence here with this statement ;).
>You may say whatever a decision a scientist makes on concepts such as these is obviously the best - but then history would show you totally incorrect.
That wasn't what I meant at all. I meant it is normal for scientific evidence to be part of answer for philosophical question, and there is no conflict to be found with that. In fact, up until the middle of last century when science becomes too specialized, it's fairly normal for scientist and mathematicians to also be engaging in lot of philosophy (Bertrand Russell and Hilbert comes to mind). Several branches of logics are also intertwined with philosophy development. The seemingly separation of science and philosophy nowadays is more a matter of specialization than anything (there is a quote on this).
"Vital force" was an incorrect scientific hypothesis, but the philosophical question of "is there anything fundamentally difference between life and non-life objects" is answered by scientific advancement. And I said that specific philosophical questions can be made obsolete, just as scientific questions can be made obsolete and irrelevant. That is no indictment on either philosophy or the scientific method.
From my understanding, science is more the concern of facts, and philosophy is the framework for study and interpretation of those facts ("truths", if you will).
> "is there anything fundamentally difference between life and non-life objects" is answered by scientific advancement
No it isnt. Science has only made one candidate for the meaning of "fundamental" trivial (in particular, that the physical substance of living things is the same substance of non-living things)- there are many other senses in which living things and non-livings things are fundamentally different. For example, all moral agents are necessarily alive. All non-living things are necessarily not moral agents.
Hm. Not agreeing here. Either one is derived from / defined by the other somehow, so they are two words for one thing. Or there is supposed to be some property of life not mentioned that is necessary for moral agency. In which case a perfect simulation of a living thing, not alive in itself but identical in all knowable ways by definition, would have to have moral agency?
I think "vital force" is the term you might be looking for. While almost any scientist would just chuckle at the idea, remnants of it are still quite common in modern philosophy.
Who/what are you thinking of when you say it's common? There's exactly one[1] post 1950 Anglosphere philosopher I could credibly associate with the idea, out of literally hundreds I've read: John Searle. And arguably that's a dismissive appraisal of what he thinks (but I don't think his view makes any damn sense, so that's what I'm stuck with).
Philosophy can change what categories count as 'life'. Science can show us surprising category shifts, life forms that aren't what we thought. Both are needed. There's a lot of weird mechanisms out there.
I would not be so harsh on biologists, but I do agree that we waste far too much time arguing over garbage like this. As I used to tell my students taxonomy is just a tool to help humans make some sense of all the complexity in living systems, but it is not real.
I think that if the taxonomy is based on evolutionary paths, it's somewhat more "real" compared to the "looks alike" sense. The evolutionary paths could potentially give some insights, while grouping similar but genetically unrelated species is just a confusion in that sense.
On the other hand - classifying things based on their genome does not really help us understand the biomes.
Whether viruses are classified as life or not doesn't matter and wouldn't change anything. The important and interesting thing is that viruses probably evolved from cells.
