what is life?

[Thaurismunths]

Your mixing origin with function.  It doesn't make any difference how mitochondria became parts of cells, and it doesn't make any difference how newspapers evolved over time.  What matters is what each part does, not how it came to be doing it.

I’m sorry. I thought I was replying to your off-topic rebuttals.

Having read through the thread a few times, I think this is what’s happened:
You said:

I reject the city <as being alive> because it does nothing of itself.  It is a puppet: It moves only because the people inside it move, and only when they tell it to.  Although a human may rely on the bacteria that live in his/her body, the human's activities are self-initiated.  A living city would be a city that goes about its own activities for its own benefit, with the help and cooperation of its human inhabitants, perhaps, but not under their direct control or for their direct benefit.

But then you went on to say:

I am alive because my body is involved in a continual, self-actuated process of maintenance and renewal.  I have very little to do with this: I stick food in the food hole, but my life processes are almost entirely automatic.  The specific details of how I obtain the food are incidental and not important to defining me as "alive."

By which you defined yourself as ‘not alive’, just like the city.

In-between those two comments you said:

A city does not move and initiates nothing.  It sits inert until humans come along to flip its switches and turn its keys.  Humans animate it and without humans it is nothing.  A tree is a thing unto itself; it doesn't have a lot of little tree-people running around inside it, flipping switches.
A city does only what people make it do.  A tree does its own thing.

And I brought up mitochondria because mitochondria fit your qualifications of non-living but fit most all of the scientifically accepted qualities of being a ‘living’ thing in hopes that it would help you stretch your definition of “life” to include more unusual things.
You objected to the mitochondria reference because it was an organelle, like the Golgi apparatus or the lysosome, which is when I got in to mitochondrial history to support that they aren’t at all like other organelles.
You made a counter example of your ad department, which I thought it was a perfect analogue to the mitochondria example, and one that you could more readily grasp. Instead I ended up defending your counter-example.

Your argument that an organ can’t be a living thing:

An organ remains intact and alive only by its union with the other organs, by serving the needs of the organism.  You can't just have organs running around on their own.  They have to be part of a whole in order to have any function or relevance.  To talk about an organism serving the needs of the organ is silly because an organ cannot be defined except as a part of the organism.

Take my workplace.  Advertising sells and makes ads for the paper.  The pressmen print it.  The newsroom writes the articles.  Photographers take the pictures.  The managers... do something or other... I guess.  It would make not sense to talk about the paper serving the needs of advertising as if advertising were the crucial piece and all other departments existed just to prop it up.  All the parts are necessary and every part is worthless and non-functional without every other part.  The paper is the organism and all the departments are organs.  Each organ works to support the whole organism and is supported itself only because it is a piece of the organism.  We have to define the departments with reference to the paper, not vice versa.

Only went to, again, exclude yourself from the category of ‘living’ because you are only an organ in the ecosystem.

As for your robot, I disagree that a self-oiling, self-replicating robot is a living thing.
I do agree that a self-fueling, self-replicating, self-actuating, self-repairing robot that “takes purposeful actions to maintain itself and keep itself going.” is living thing.
Your first description was insufficiently vague.

Did I cover all the salient points?

I don't know where you'd like to go from here, but I'd love to know how you define life, and where you draw the lines in the sand.

EDIT: I was being rude.

[Thaurismunths]

Do you suppose today's story selection was influenced by this thread?

I don't know about that.
But I could see his choice of intro topic relating to some other threads on here.

[Mr. Tweedy]

I think it was inspired by some genre-related fighting on the "Frankie the Spook" thread.

[Mr. Tweedy]

I don't think I ever did contradict myself, but that argument is boring me at the moment, so:

There is an important distinction that has been confusing us all, I think.  (Someone else brought it up already, but I don't remember who.)  There is a difference between a thing that is living and a thing that is an organism.  Every cell in a body can rightfully be said to be alive, and even the parts of a cell (like mitochondria) are also alive.  If you cut off your finger, there is a certain window in which you can sew it back on and keep it, because it takes a while for the cells in the finger to shut down and die.  Your severed finger is still living, but it is not an organism.  If you cut off your head, your buddies would theoretically have a few minutes to reattach it before the brain died.  In the meantime, both the head and the body would still be alive, but neither piece would be an organism.

I've been thinking about this a bunch the last few days and I think there is a simple quality that is possessed by all organisms that we could probably use to define life: Life is self-building.  Every organism builds and rebuilds itself from materials in its environment.

[Thaurismunths]

I don't think I ever did contradict myself, but that argument is boring me at the moment, so:

I'm sorry I bored you. I will try to avoid doing so in the future.

[eytanz]

Life is self-building.  Every organism builds and rebuilds itself from materials in its environment.

Tweedy, that's not really different than what you've been saying before, and still just as problematic - until you give a coherent notion of "self" - one that includes humans and robots but excludes cities and mitochondria, and, according to you, has nothing to do with self awareness - it's impossible to tell if something builds itself or not.

[Mr. Tweedy]

I don't think I ever did contradict myself, but that argument is boring me at the moment, so:

I'm sorry I bored you. I will try to avoid doing so in the future.

Geez, don't take stuff personally.  I said I was bored with the argument, which included my own words as well as yours.

I don't feel like arguing for the coherency of my own argument: The only point would be prove that I'm a smart guy, and trying to prove that would be boring (and probably futile).  If my metaphors and analogies cause more confusion than clarity, then I'd rather admit they failed and let them die than waste time arguing over whether or not they're good.

[Mr. Tweedy]

Life is self-building.  Every organism builds and rebuilds itself from materials in its environment.

Tweedy, that's not really different than what you've been saying before, and still just as problematic - until you give a coherent notion of "self" - one that includes humans and robots but excludes cities and mitochondria, and, according to you, has nothing to do with self awareness - it's impossible to tell if something builds itself or not.

So I guess your with ClintMemo in saying that we have no definition for life?

[ClintMemo]

I would say, as humans, we have an imperfect ability to identify something as alive or dead based on some undefinable characteristics that we perceive in said thing.   Sometimes the label is obvious (a cat is alive - a rock is not alive). Sometimes it is not (robot may or may not be alive - we can't be sure).

Maybe that means the "alive" is no different than "good" or "evil" in that it cannot be precisely defined and may simply be a label that we humans have created for our own convenience but has no definition in reality.

I said maybe.

I remember that this thread started as an off shoot of another thread, but today I'm old, so I can't remember where it came from. 

[eytanz]

Life is self-building.  Every organism builds and rebuilds itself from materials in its environment.

Tweedy, that's not really different than what you've been saying before, and still just as problematic - until you give a coherent notion of "self" - one that includes humans and robots but excludes cities and mitochondria, and, according to you, has nothing to do with self awareness - it's impossible to tell if something builds itself or not.

So I guess your with ClintMemo in saying that we have no definition for life?

Well, I certainly don't have a good definition - I have an intuitive sense of what I want to call alive or not, but I feel there's a huge grey area of stuff that I'm just not sure about. You seem to have strong opinions about what is alive or not, but you have consistently been unable to actually define life in any way that doesn't just defer the problem to some other undefined notion.

When this thread started, I thought that it was possible, though not easy, to come up with a definition of life that's actually useful for something other than narrow technical applications. But your posts have mostly convinced me of the reverse, since you seem to be the only person here who really thinks they already have a definition like that, but - judging purely by the conent of your posts - you are just going by arbitrary intuitions as well.

[Mr. Tweedy]

I honestly don't see what you mean.  My "builds itself" rule is very much like what I was saying before because I don't think what I was saying before needs much revision.

My idea is that anything which engages in self-construction is a living thing.  Anything which is constructed by external forces is not living.

The source of resources for the construction project is not important.  Whether a critter lives in a vacuum and eats rocks or must be kept in a mauve box at 82.3% humidity and fed caviar, all that matter is that, once it gets the resources, it uses them to build itself.

A city does not build itself.  People have to build it, so it is not alive.

A virus does not build itself.  A cell has to build it, so it is not alive.

A snowflake does not build itself.  It is constructed by external forces, so it is not alive.

A bacterium does build itself, so it is alive.

A dog builds itself, so it is alive.

A mitochondrion?  Well, at first I rejected the idea that a mitochondrion was an organism, but I see Thaur's point as plausible.  I'd need to study it more, but, as far as I know now, I suppose you could say that a mitochondrion is an organism and a cell is its habitat.  (Which brings up the odd idea of an organisms being an organ of another organism.)  But even if a mitochondrion is an organism, it still builds itself, and its host cell also guilds itself, so it doesn't screw up my definition.

That seems like a solid definition to me.  I don't see how it's an "arbitrary intuition."

[ClintMemo]

A dog does not build itself initially. It is initially built by two other dogs.

The sun could be said to build itself because it's gravity attracts outside material which keeps its fusion reaction going.

[Mr. Tweedy]

Whether or not the parents "initially build" the puppy is a matter of semantic nit-picking, I think.  Regardless, the puppy does build itself from the moment it becomes an individual puppy.  Before that, the sperm and egg exist as parts of their respective dogs, which are self-building (SB), so the SB processes never stop during the whole operation.  However you describe procreation, the SB definition still applies.

Stars?  Well, what if stars are alive?  Good for them!  Hope they get in touch someday.

Stars are not self-building, though.  Stars exist because there is no other way for them to be.  The physical laws of the universe dictate that clouds of gas must collapse and nuclei must fuse under pressure.  A star is no more building itself that a pencil is building itself when it falls of your desk.  Gravity compels the operation.  It's just what happens.

Living things are not like that.  A bunch of nitrogen, carbon, oxygen and hydrogen atoms don't have to walk around on two legs.  The atoms that constitute you would be just as happy floating around freely.  Law compels atoms to form stars.  No law compels them to form organisms.

[eytanz]

  I don't see how it's an "arbitrary intuition.

The color purple doesn't build itself. Therefore it is not alive.

Tuesday doesn't build itself, therefore it isn't alive.

A triangle builds itself, so it is alive.

---

See, I know how to take nouns and put them in the template too. It doesn't make it anything other than meaningless nonsense, however, unless the statement "builds itself" is meaningful. And while I can assign a meaning to that statement, the meaning I assign to it doesn't help me understand what you are saying. And I've asked you twice above, neither time did you care to explain. Sure, your examples aren't nearly as nonsensical as the ones I gave, but they are no more helpful.

I understand that if, and only if, something builds itself, it is alive.

Now you need to tell me how to decide whether something builds itself. Not by giving examples, because that's just making a list. I want explicit criteria. Remember, you said that life is not a gradient notion. Since life = self-building, self-building can't be gradient either. So, what I want from you is a clear-cut criteria that can divide the world into "builds itself" and "doesn't build itself".

I'm not arguing against your criteria for life. I just don't understand what it actually is. I don't want you to justify it - I want you to explain it.

[slic]

I've being reading with interest, and, Mr. Tweedy, I would point out you have been consistent with the self building idea. 

I would agree that it would be helpful to have a definition of self building.  Part of the problem has been for every example "A city is not alive" someone has provided another that seems to contradict "What if the city had a number of systems to self build?"

Following the city example, if I build a single building that had small robots which repaired it, and after getting enough raw stock created another building, etc. etc. is that alive?  I would interpret it as such using your self building definition.  But I wouldn't because it's just a self replicating object. 
What about a nuclear reaction, or fire, or, bit of a stretch, magnetic fields.  Rub a magnet against a ferrous, non-magnetic object and it becomes magnetic - that's self-replicating, kinda like cell fission.


My definition of life still involves awareness of self, otherwise I can easily argue that a rock is alive, but in hibernation. 
1. Interaction with the environment.
2. Rudimentary (or better) awareness of self (e.g. doesn't still inertly when set on fire).
 




One thing I'd like to explore LATER is how much "intelligence" is needed to be considered alive.

[Thaurismunths]

My idea is that anything which engages in self-construction is a living thing.  Anything which is constructed by external forces is not living.

Are these alive?
Spontaneous self-building silicate structures
Self Building Robots Begin Their March

[edit: added blow]

The source of resources for the construction project is not important.  Whether a critter lives in a vacuum and eats rocks or must be kept in a mauve box at 82.3% humidity and fed caviar, all that matter is that, once it gets the resources, it uses them to build itself.

By this criterion couldn't a box full of magnets be considered 'living' as they would order themselves in to deliberate shapes with no human interaction?

[Mr. Tweedy]

Hmm...

Well, what does it mean for something to be "built"?  I feel like we're getting a point where there aren't English words to distinguish between concepts, or that the words aren't precise enough.  Or maybe my vocubulary is just too small.   

When I say "build" I mean it in the sense of a building.  A building is never an accidental conglomeration of parts; it is always done according to a plan.  A blueprint of some kind is always the beginning, and the building is the execution of the blueprint.  For something to be built (in this sense) there must be a plan which precedes the product.

I don't think we can call something "built" if it comes to be as an inevitable action of physical law.  I'm thinking of the crystals and stars ClintMemo mentioned.  Crystals and stars form simply because that is the natural state that matter takes under certain conditions.  When water condenses below a certain temperature, it turns into crystals.  It has to turn into crystals: There's nothing else it can do.  A star has to burn.  There is no other physically viable option but for these things to occur, given the physics of our universe.

But things like skyscrapers or cars or dogs are not inevitable consequences of physical law.  Law might dictate that iron should exist, but it does not compel iron to mix with carbon and form itself into an an engine.  Similarly, no law compels a pile of dirt to turn into a flower.  In both the case of the engine and the flower, matter was taken and reshaped according to a specific, pre-existing plan.  Both things were built.

I guess that's my criteria for building.  An object that is assembled according to a blueprint is built.  An object that comes to exist without benefit of a blueprint is not built.

So, both the car and the flower are built, but they are not both self-built.  People have to come and build the car; it contains no mechanism for building and no blueprints to build from.  The flower, in contrast, contains its own blueprints and mechanisms which are able to execute them.

So, these are my more specific, hopefully more satisfying criteria for a self-building object: The object must contain its own blueprints and (provided the necessary materials) be able to execute them.




...It shows just how lame my job is that I can spend all this time writing posts and not decrease my productivity.

[Thaurismunths]

So, both the car and the flower are built, but they are not both self-built.  People have to come and build the car; it contains no mechanism for building and no blueprints to build from.  The flower, in contrast, contains its own blueprints and mechanisms which are able to execute them.

So, these are my more specific, hopefully more satisfying criteria for a self-building object: The object must contain its own blueprints and (provided the necessary materials) be able to execute them.

This brings us right back to cities being living things.

[Mr. Tweedy]

So, both the car and the flower are built, but they are not both self-built.  People have to come and build the car; it contains no mechanism for building and no blueprints to build from.  The flower, in contrast, contains its own blueprints and mechanisms which are able to execute them.

So, these are my more specific, hopefully more satisfying criteria for a self-building object: The object must contain its own blueprints and (provided the necessary materials) be able to execute them.

This brings us right back to cities being living things.

Would you consider a wasp nest to be living?

[Listener]

A dog does not build itself initially. It is initially built by two other dogs.

I lol'd.

[Thaurismunths]

So, both the car and the flower are built, but they are not both self-built.  People have to come and build the car; it contains no mechanism for building and no blueprints to build from.  The flower, in contrast, contains its own blueprints and mechanisms which are able to execute them.

So, these are my more specific, hopefully more satisfying criteria for a self-building object: The object must contain its own blueprints and (provided the necessary materials) be able to execute them.

This brings us right back to cities being living things.

Would you consider a wasp nest to be living?

No, because they are far too simple to exhibit any more of the qualities of life then does a lean-to.
The first paragraph of The Transportation System Inside a Living Cell by Clare Yu of University of California, Irvine does a beautiful job of comparing the intra-cellular operations to that of a cell to those of a city. For brevity I've pasted it below:
A living cell is like a city in its infrastructure. It has workers (proteins), a power plant (mitochondria), roads (actin fibers and microtubules), trucks (kinesin and dynein) whose cargo are containers (vesicles), factories (ribosomes that make proteins), a library (genome), post ofice (golgi apparatus sorts, packages and modifies macromolecules for secretion or for delivery to other organelles), and police (chaperones). Wayward or mal-formed proteins get a ticket (ubiquitin) and then get shipped off for degradation. Cells are also involved in exporting and importing. Communications and regulation occurs through complex signaling pathways that help keep everything running smoothly.
If you invert this you can see how easily a city directly resembles a cell, and cells are definitely living.
A wasp's nest has none of these things.

[Mr. Tweedy]

Yu is using the city as a metaphor to explain the cell.  She is not suggesting that a city is alive.

A wasp nest is simple because wasps are simple creatures with simple needs.  I picked it for its simplicity, but something a little more complicated, like a termite colony or a beehive, has many of the city-like qualities Yu mentions.  In each instance–the wasp nest, the beehive, the human city–the creatures in question build a structure that suits their unique needs.  It is the creatures who are alive, and they build structures that suit the needs of their way of life.

A city does not meet my criteria for self-building any more than a wasp nest does.  Every step and stage of its existence, from the discovery of its site to its bicentennial parade, are planned and executed by humans for human benefit.  Humans make the plans and do the work: The city does not do this for itself.  A city is a tool of humans to advance human life.  It is a really big, complicated tool, so big and complicated that is difficult for the very people who use it to understand, but it is still just a tool.  It does not build itself: People build it.  Human hands move the bricks into the places where human minds wish them to be.  Humans drive the cars and make the purchases.  This is economics and sociology.

All life that exists in a city is human life.  The city is built by humans to serve humans.  What we build is more complicated than what a wasp builds because we are more complicated than wasps.

A city, in principle, could perhaps be alive: That would something for sci-fi to explore.  But Chicago doesn't cut it.  Chicago does not build itself.  Chicago is built by humans.  It is what humans decide to make it, no more, no less.

[eytanz]

A city, in principle, could perhaps be alive: That would something for sci-fi to explore.  But Chicago doesn't cut it.  Chicago does not build itself.  Chicago is built by humans.  It is what humans decide to make it, no more, no less.

See, every time I think I understand you, you come back and say something like this. If life is not about self-awareness, how does decision-making come into it?

You said earlier that a robot can be alive, so being organic and using organic methods of growth/reproduction is not necessary.

You also said that humans are alive, so it is possible to have living things whose continued existence depends on smaller living symbiots.

You haven't said so, but I'm assuming you'll agree that a flower that can only reproduce if pollinated by a bee is alive - so the ability to control your own reproduction is not necessary.

So I'm still not sure how all the puzzle pieces come together for you in a way that still excludes Chicago.

[Mr. Tweedy]

I didn't say anything about self-awareness.  (Slic mentioned self-awareness, but I think he was referring to the ability to react to stimuli, not to consciousness.)

I only said "decide" because humans are the ones building and humans do decide things.  That's incidental.  Just knock out the words "decide to" from my sentence: "Chicago is what humans make it, no more, no less."  It doesn't change what I was saying.

Humans in a city are not like mitochondria in a cell*.  A cell is busy doing its own work, and it relies on the mitochondria for important help.  A cell is involved in myriad activities in which the mitochondria play a very limited role.  Not so with a city.  Chicago is not busy doing its own work while relying on its human residents for limited assistance.  Humans do all the work.  Humans play all the roles.

Imagine a cell in which all the parts that Thaur mentioned (ribosomes, etc.) are built, maintained and operated by mitochondria, according to plans stored in the mitochondria.  That cell would not be alive.  It would be a mitochondria city or nest, not a living thing in itself.  The mitochondria alone would be alive, and the rest of the cell would be just their tool.



*Assuming, for the sake of argument, that mitochondria are organisms.

[Thaurismunths]

Mr. Tweedy,
I believe you are playing dirty pool.