Failed Attempts At Defining Life
Failed Attempts At Defining LifeUntil the DefinitionOfLife, it's not just rank amateurs who failed at defining life. Professionals did too. People have wrestled with this roughly forever. For instance:
These are not all "failed attempts". That misunderstands the nature of the topic, and of the problem.
A definition's success or failure at defining a concept is an objective thing. These ARE failures. Objectively. They're certainly popular but then popularity isn't the same thing as success.
Life: The Spirit of God as it is revealed through His Creation. http://www.ourfoothills.com/butgod/glossary.htm
Life: The state of being which begins with generation, birth, or germination, and ends with death; also, the time during which this state continues; that state of an animal or plant in which all or any of its organs are capable of performing all or any of their functions; used of all animal and vegetable organisms. (Gray's Medical Dictionary)
http://www.dllab.caltech.edu/cns175/handouts/hw1.html:
Physiological Definition: Focuses on physiological functions such as breathing, moving, digesting, etc., to construct a list of requirements that will distinguish living from non-living. Outdated.
Metabolic Definition: Centers on the principles of exchange of materials between the organism and its surroundings as the only requirements for the organism to be alive. Too narrow? or Too general?
Biochemical Definition: Classifies living systems by their capability to store hereditary information in nuclear acid molecules. Focuses on DNA/RNA. Too narrow. Genetic Definition: Focuses on the process of evolution as the central defining characteristic of living systems, without regard to how the information is coded (i.e., independently of substrate).
Thermodynamic Definition: Describes systems in terms of their ability to maintain low levels of entropy (i.e., disorder) despite a noisy environment. Too general?
Physics-based Definition: Life is a property of an ensemble of units that share information coded in a physical substrate and which, in the presence of noise, manages to keep its entropy significantly lower than the maximal entropy of the ensemble, on timescales exceeding the ``natural'' timescale of decay of the (information-bearing) substrate by many orders of magnitude.
http://www.ai.mit.edu/people/unamay/living-machines/life-defns.html "A network of inferior negative feedbacks subordinated to a superior positive feedback."
The only one with any merit is the Physics-based Definition. On the positive side, it's correct. On the negative side, it's clear as mud and doesn't shed an iota of light on what life or its function are.
From DefinitionOfLife
Attempting to define life using boundaries...
How about: A distinguishable and bounded entity with an information content that makes it actively use and manipulate the entities and information content in the environment to maintain and possibly evolve its information content and entity structure is called 'alive'.
It's three times longer without adding anything to the definition above. Except for it being bounded ... . Further, it isn't clear that "use the information in its environment to maintain its information" is meaningful.
But, it eliminates the use of the vague word 'complex' and the superfluous word 'thermodynamic'. (Are AI entities really thermodynamic? Yes, see below). Bounded doesn't contradict non-corporeal entities since for instance the bounds of AI entities are their actual program and data (and what happens when they share an unconscious?). In order to label something as alive it must be clear where the alive entity begins and ends, thus 'bounded'.
If all bounded means is that the object in question isn't omnipresent, it doesn't contribute a heck of a lot. The word complex is vague, but necessary, as per below. And thermodynamic isn't superfluous either, since we are dealing with entropy and information, as per below; AI entities just follow different rules of "thermodynamics." Most of this is already hashed through.
alternative: A thing is alive if there is at least a partial barrier between "the environment" and "the thing" such that the thing increases the entropy of its environment in order to maintain or decrease the entropy of itself and maintain the partial barrier. - Doesn't this apply also to a refrigerator?
The emphasis on the barrier is interesting but it also detracts from the complexity of the system (by calling it 'thing'). A serious problem is that the sun is alive by this definition. Also, this definition precludes the universe being alive, which it could be if the entire universe were transformed into a single contiguous self-repairing computer system. In other words, this definition is very different from the first one.
The complexity of a thing is not relevant to whether the thing is alive or not. The semi-permeable barrier I would say is an absolute requirement for life. The sun doesn't have such a barrier and therefore is not alive. The universe is not alive by this definition either, since there is no "environment" in which the universe is contained. However, a refrigerator would be alive by this definition (and also by the first definition given above) which I think points out the lack of completeness of both definitions.
This is incorrect. Refrigerators do not maintain their structure any more than cars do. In order to be alive, a system has to be self-repairing and/or self-maintaining on some level. Self-cleaning ovens are not an example of self-maintenance since what is being maintained is not the oven's quality of being an oven but rather its utility to human beings.
Self-repairing and self-maintaining are not part of this (alternative) definition. All non-robotic AI will be non-repairing but I'd still consider them alive.
AI in a SolidStateCivilization would be self-repairing and self-maintaining. AI only seem to be non-repairing if you think about them in the context of their physical substrate, which contradicts the assumption of AI as non-corporeal entities! An AI is a self-modifying program, a program that organizes, orders, maintains and repairs its own memories and knowledge. Further, computation is inherently thermodynamic though this only becomes obvious when you're using reversible computers. IOW, any program which uses computational cycles is a thermodynamic system and any program which uses computational cycles to error-check itself qualifies as alive. AI qualify as alive by the first definition. On the other hand, they do not qualify as alive by the alternative definition since AI permeate their computational environment and even permeate each other.
There's no such thing as a "non-corporeal entity". The AI program is no more alive than the pattern of my neurons is alive when separated from their physical nature. Just because it's electronic doesn't mean it doesn't have a physical form.
This is absurd and no more a reasoned argument than the bland assertion that "the Earth is flat". A program can move from computer to computer so it is blatantly self-evident that the physical computer is not an integral part of the program but is its environment. Exactly like 'spacetime' is not an integral part of human beings but rather their environment. How can anyone on Wiki not understand what a computer program is?
Why isn't complexity relevant? As discussed below, a living system has to have a low enough entropy, or high enough information content, to prevent continuous spontaneous generation. Otherwise any living properties are going to be indistinguishable from background effects.
In order to assess the relevance of complexity it would first be necessary to have a definition of complexity. If a barrier between "self" and "environment" is required then living properties are easily distinguished from background effects on the basis of which side of the barrier they are on.
Which is why we've been using terms like information and entropy. In any case, it's ok to use slightly vague concepts for defining life because life itself is a vague concept (see below). And note that your barriers aren't so high above such considerations: they're also vaguely defined, and need to be treated in such a way that barriers can't be part of the background effects (else they would be useless for distinguishing things). I don't want to go into this in detail, for as discussed below, barriers don't work for viruses or sponges.
A semi-permeable membrane shouldn't be necessary. First of all, it only means something in terms of familiar life. If you consider the possibility of electronic life, or even mechanical life, it no longer makes any sense.
The term "membrane" does not appear in the above definition so it is correct that it is not necessary. It is however sufficient and is the solution many biological organisms use; this doesn't preclude alternative solutions. The key point is that there must be some way in which the stuff that makes up the lifeform is prevented from diffusing away into the environment and likewise there must be a way to prevent the environment from infiltrating the organism in an uncontrolled manner. The alternative is for there to be no distinction between the environment and organism, but we are talking about organisms which are alive living in an environment that is not alive (unless everything is alive in which case the definition of life is uninteresting). In terms of electronic life, the barrier would be the electrically non-conducting material which prevents the electrical signals from simply diffusing away.
This is sophistry. Such a "barrier" does not surround the electronic organisms. In fact, this barrier defines the environment of the organisms. Barriers are no more the defining characteristics of life than evolution is. A barrier only serves to delimit the boundaries of an entity. That is, a barrier lets us state that an entity exists before even talking about whether or not the entity is alive. -- rk
I don't know if it's sophistry or not, but the requirement of a semi-permeable barrier eliminates from contention some of the more difficult counterexamples to definitions of life such as fire, crystals and language. - and also computer viruses and sponges. Saying living things can't start with F also gets rid of fire, but that's not sufficient to make it a good criterion.
Well, I was actually responding to the voice that stated it was... I don't think it is necessary to have a physical barrier preventing material from diffusing away if the material is cohesive enough, see the discussion on sponges below. As for electronic life, as opposed to mech life, I meant in a computer universe where diffusion need not apply so barriers don't have to be set. Tierra is a good example.
Second of all, it doesn't really apply to normal biological things. Viruses are, at the very least, incredibly close to being life; their outer casing isn't semi-permeable and is completely removed when the virus is active. People have skin, but I think there are some simpler multicellular organisms - SlimeMolds? or sponges might fit - that have no outer cover, the cells just sticking together; should these, then, be considered non-living assemblages, despite having differentiated components?
A virus is better looked at as an organism with two distinct life cycles. When outside a cell the virus is enclosed by the viron particle. Whether the virus is "alive" at this point or not could be debated. The second part of the viral life cycle is as a conjoined organism with the cell it infects. At this time the cell and the virus both share the cellular membrane in order the separate their contents from that of the environment. In the case of SlimeMolds? or sponges, the individual cells are clearly alive by the above definition. Whether or not the assemblage constitutes an independent life form could be debated.
When the virus is inside the cell, it has no membrane, and so by your criteria is not alive. It doesn't matter that the cell it's in has a membrane, since that is only relevant for whether the cell is alive. And in fact a membrane-bound cell is optional; a solution of ribosomes and amino acids would do as well.
That's correct, when the virus enters a cell, not only is it not alive, but it doesn't even exist. Instead there is a virally infected cell. Try to point to the location of the "virus" within the cell -- you can't. The solution of ribosomes and amino acids is alive indeed without a membrane, so long as there is some kind of container to hold in the ribosomes and amino acids which will allow in energy in a form usable to those components. Biology has evolved phospholipid bilayers for this purpose, but there are many other possible solutions to this problem, dialysis tubing perhaps.
A virus inside a cell takes the form of a nucleic acid, and you can easily point to it's location. As for it not being alive, well, this is the stage where it shows all of its life-like characteristics. Furthermore, so long as the two genes don't become amalgamated, the distinction between a virally infected cell and a cell containing viruses is no more real than the distinction between a man with the flu and man containing flu viruses. An infected cell contains viruses, which don't need membranes to be distinct as they are simply molecules.
You can point to the location of the nucleic acid that is the viral genome, but that nucleic acid isn't "alive" by either definition, rather the nucleic acid that codes for the virus is now part of the complement of nucleic acids in the cell, so rather than a virus existing as an independent life form within the cell, we have a cell that knows how to construct viruses.
It's alive by RK's definition (degeneration is prevented through back-up copies), through mine, and even through RobHarwood's wacky one. It's absurd to claim the nucleic acid isn't the virus, since the virus doesn't have any other components except an optional inert shell. Protection seems pretty trivial - is the shell an intrinsic part of a hermit crab? Plus, if you want, we can go down a step farther and talk about virioids, behaviorly identical RNA molecules that never have a shell. There is no difference between a cell who knows how to create viri(oids) and a cell with viri(oids) within it, since the instruction template for their creation is the creature itself.
SlimeMolds? are debatable, perhaps, but sponges are not. Sponges have distinct cells for reproduction, feeding, swimming (in larval form), and whatnot. It's clearly an organism in its' own right. It just doesn't need an outer membrane, because the cells stick together. Claiming that what exactly holds the cells together is important is beyond me.
Let's suppose that what holds the cells together is not important. If that is the case, then you could remove whatever it was that holds the cells of the sponge together without harming the sponge. If you do this though, the cells of the sponge will all float away into the environment. The barrier does not necessarily need to be external, but there does need to be a way to keep components of the life form from dispersing, and to keep components of the environment from invading at will.
The term barrier does not apply to cohesive forces between cells. If you are simply asserting that living things need some sort of forcing holding them together, you are correct. But in that case the sun does have a "barrier," namely the gravitational force its parts exert on each other. Sheesh.
Not quite, "barrier" means not only "keep things in" but also "keep things out". The sun's gravity does the first part, but not the second.
Sponges don't keep things out, though. There is nothing to prevent other objects from sticking to the sponge, and external water is actively channeled in so that almost every cell has exposure to it. The difference still doesn't work. On the other hand, the sun does have a mechanism to keep at least small objects out: radiation pressure.
Do gravity and radiation pressure together constitute a solar boundary (the heliopause, maybe)? And why would it matter whether or not things can fall in, when space is virtually empty? If water was anywhere near as clean as space, I suspect cells wouldn't have evolved any protection mechanisms (though they'd have one heck of a time finding energy). I'm sorry, but this criterion barely matters for anything, let alone life-nonlife status.
Yes, any definition of Life that includes a spiritual element can be defined as a failure. All of us here in FlatLand know that if it can't be defined in terms of geometry, then it can't be true. -- FlatLander
Pathetic flame bait, cute and entirely vapid. To the many people who think amoebae are alive and don't think they have spirits - see ZenoBuddhism - it's not even relevant to this page. Would it be too much to hope it can be removed without causing an edit war?
Feel free to remove. Nothing sacred about it. I just find it amusing that so much effort is expended in defense of the "life is all about chemistry" model. I don't know what makes the idea of some kind of not-of-this-plane energy or animating source (or spirit, if you prefer) so heretical and scary, but I've come to understand that introducing or mentioning the concept will never make me popular. Nevertheless, I do from time to time tap the glass with that model to see if anyone will glance that way.
Animating spirits are popular when discussing people, but not many people bring them up for unicellular organisms. In fact, for some protozoa the part of behavior that most people invoke such things for - motion and interaction with their environment - has been explained very well using chemical properties, though as always the over-all metabolism is not well known. In any case the question on this page is what characterizes life, and that obviously isn't an aphysical animating force, since it's not even obvious one exists. Whether some or all living things have one is a different question - incidentally, one that there is no evidence to suggest yes for, but that's not relevant here.
> idea of some kind of not-of-this-plane energy or animating > source (or spirit, if you prefer) so heretical and scary,As a planet where has it ever gotten us? So you say there's a god or whatever, now what? Should we stop trying to figure out how the universe was created or how life works or how anything works for that matter? Or should we just pray all day and kill each other because your god isn't my god? Nobody can say yet where the universe came from or how it works. But which path has led us further?
Actually, it's not about "God instead of physics." It's about physics, the whole physics, and nothing but the physics including whatever God/god or spirit(s) as may exist rather than "physics must never consider non-physical phenomena" as a premise. Yes, do all the physical sciences. Include all the data. If there are phenomena not explained by the sciences of today, then we're not done yet.
What would an inclusion look like? If we said all this is complex there must be a designer, how would it change anything? And as it doesn't explain anything yet, why make the premiss at all?
Well, let's go at this from another side. You get someone like StephenHawking saying that the observer affects the outcome of an experiment. Without touching it. Okay, now it gets documented. But we have a rule that says this can't happen in physics. Do we discard the evidence because it doesn't fit the model, or look for revisions to the model to account for the evidence?
When we were home schooling our kids, we used a curriculum that was published by a group that couldn't resist saying that the rules of math were a gift from God (or words to that effect). I had to park that book and get another, since the object of the exercise was to learn math, not look for extensions to BibleSchool?. At the same time, I encouraged them to allow for the influence of Life on the rules of physics, rather than view Life simply as the product of physics. I have been witness to too many things to simply discard the idea that there might actually be somebody home. I can't sell anyone (except, perhaps, the choir) on the idea of "non-physical life" based on my experiences; the most I can do is say, "hey, hope you're not overlooking this possibility," and trust that not everyone will laugh it off.
You can't live in this world and overlook the possibility. Still, what would inclusion look like? How would it change anything? The only change i can see is negative. We again replace faith for thinking. In a thousand years, after we understand the world much better, if we come to the conclusion that there is a spirit, then so be it. But for now we are babes with a lot of growing to do.
I'm not talking about faith. One day you're looking in a test tube or at a photographic plate or at a 'scope and reviewing the math for the results and you realize that the only thing that accounts for what you're seeing is the influence of a non-physical entity of some kind. After having exhausted all the alternatives it keeps coming back to "someone" rather than "something" acting on the outcomes. It's now time to find a way for the math to account for this. I don't care if it's easy. I don't care if it requires the invention of new nomenclature. If you detect it, you catalog it. This is just science.
"Inclusion" is nothing more than the kind of "inclusion" you do when you realize there has to be anti-matter. You invent new names, new math, and new descriptions.
New descriptions to do what? The magic box? An input goes into the magic box and magically comes out explained? Not very useful. You can't even come up with anything remotely useful in your desire to include god. It sounds very much like faith until you can some value add for including god.
Oh, lookey, Mommy, the man thinks science is a magic box. He's spoiling for a fight. He's being intentionally obtuse. Would you kindly explain how the scientific community finally came to terms with anti-matter? Did it require new nomenclature? Did it require some new rules? Was a magic box used for this?
Fiddlesticks. Either there is evidence of non-physical influence or there's not. Don't like the word "spirit" or "god" or "entity" or is it just "non-physical" that we have trouble with here? Rant, rant, rant. If there's no evidence of a non-physical influence, then no problem. No name calling required.
If, on the other hand, there is evidence of some non-physical influence then, as a scientist, you get with the program and classify it. Or, if you prefer, you can dismiss it as "magic, and everybody knows there ain't no such thing." So, since anti-matter showed up in ScienceFiction before it showed up in science, and since everybody knows bad fiction doesn't make good science, this whole anti-matter thing needs to quietly go away. I had a set of science encyclopedias, published before man climbed the moon, which "doubted" the existence of anti-matter. I guess between then and now something in the evidence must have changed.
In case you have misunderstood, I'm not trying to "prove" that there is spiritual influence in the physical world, including this thing called Life, I'm simply making sure the door doesn't get too firmly slammed on the idea. I'm also not interested in slamming the door on BlackHole research, even though not all scholars are convinced of their existence.
I know that the idea of anything remotely spiritual involved in science scares hell out of some people. They worry that admitting there might be something like a "soul" or whatever might suddenly cancel gravity or something. To the point where they'll go to any lengths to "debunk" the idea. Well, there ya go. PoliticallyCorrectScience?. Sorry, my time's up, I have an appointment to be burned at the stake. Something about heresy.
Pro's And Con's summary of given definitions:
Product of Natural Selection
Attempt "Candi" moved to DefinitionOfLife
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