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Why call it alive ?

  1. Forget the whole living/non-living distinction; it's useless.

    8 vote(s)
  2. Devise a working definition for "alive"; it is an important distinction.

    6 vote(s)
  3. Use one of the definitions that already exist, and accept the consequences.

    3 vote(s)
  4. other...

    4 vote(s)
  1. Dec 3, 2003 #1
    Why call it "alive"?

    It has been mentioned innumerable times in previous threads that "life" has no working definition. Most of the definitions that people have tried to devise have either excluded some things that are still considered living, or have included some things that are certainly not considered living.

    So, my question is, why did we ever come up with this distinction in the first place? Is it part of our evolutionary (cultural or organic) heritage? What use does it really serve in the long run?

    As it is, I see us as having three choices:

    1) Abandon the whole "living/non-living" distinction altogether, and move on.

    2) Form a fully functioning definition, that allows only those things which we would all agree are "alive" and excludes those things which are obviously "non-living".

    3) Use one of the definitions (sets of criteria) that we have already devised and accept the consequence that either some of the things that we thought were "alive" are not, or that some of the things that we've assumed to be definitely "non-living" are indeed alive.

    Please give reasons for which you vote for. Along with such reasons, any comments, corrections, or questions that remain on-topic are appreciated :smile:.

    Oh, btw, if you think you've got another alternative, then just choose "other..." and then post your alternative (this should seem self-explanatory, but there've been problems in the past, so I figured I'd make sure).
  2. jcsd
  3. Dec 3, 2003 #2
    I think it important that science comes up with a working definition of what life, being alive, is because accurately defining it would lead to better understanding it and help in its study. Not just for knowledge's sake but for all of lifes sake. Who knows it may lead to saving lives.
  4. Dec 3, 2003 #3
    I ask you, though, how can one say that life even exists, if it has not working definition? IOW, how can it be important to "life" for there to be a definition of it, when its lack of definition makes it seem as though it doesn't exist at all?

    I may playing DA here, but I kind of do really want an answer to this, personally.
  5. Dec 3, 2003 #4
    The same way that we can say that matter and energy exist without knowing what is is or being able to define it by other than it's properties just as we attempt to define life. Does a photon exist?
  6. Dec 3, 2003 #5


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    "Alive" and "life" are not special. There are many words that have this property. My wife and I argue about whether something is blue or not. Most words have their black and white zones, and grey areas.

    The reason why we argue is not because the concept is nebulous, but because it is important. No matter what definitions you make, because of the importance of the issues, some people will see different things as falling into different catagories. You can draw up your new definitions with the greatest of care, but you are defining your concepts with words. These words will have subtly different meanings to every person. These differences blur the distinctions you think you so carefully made.

  7. Dec 3, 2003 #6
    Is there a distinct difference between something that is alive, and something that is conscious? Should there be? Would a machine that has the ability to reproduce be considered alive? If not, then why would we be considered alive?

    I don't think there can be an accurate discription of what is alive, because of the above questions.
  8. Dec 3, 2003 #7
    The more I look at this subject and the more I read into AI and philosophy of the mind, the more any word like "living" looses all meaning. What is important is the consequences. Why? We will never be able to tell if something is 'alive' or if it is faking, the same way as we will never be able to tell if a computer is 'conscious' of if it too is just faking (of course faking implies that it is doing it deliberately, and therefore it is both alive and conscious, but hence is the nature of language, deal with it)

    If we attribute meaning to things in terms of its consequences then all of this becomes irrelevant. It acts like life, treat it like it is. Definition will never help us here, as we are bound to rope in a lot of false rejections and false positives, and that’s just not something that you should do to anything that’s 'life'. Just treat it like it is.

    As for life and consciousness, well, if 'life' is simply a matter of complexity, then maybe consciousness is a complexity that arises from life. They can be treated the same way, but it’s not necessary that the presence of life imply consciousness.
  9. Dec 3, 2003 #8


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    Whose work?

    There doesn't need to be just one definition, just as there's not one definition of 'force', 'energy', 'action', etc; there are good working definitions used by the folk who need them, in different fields (there's another) of endeavour.

    So, it's maybe more important to ask 'who needs the working definition, and for what purposes' than to get hung up on any particular one, let alone try to find a universal one for all of science.

    My own interest is ET(L), and a useful definition would include stuff like persistent and repeated deviations from thermodynamic equilibrium, chemical equilibrium; something about organisation, hierarchy, patterns; and more (e.g. reproduction in some sense).
  10. Dec 4, 2003 #9
    There's a difference. Postulating the photon helps us further our knowledge of what we know to be occuring at the subatomic level. What does postulating a distinction between "alive" and "non-living" help?
  11. Dec 4, 2003 #10
    Yes. Until we devise a working definition, it doesn't mean anything to be "alive", but it does mean something to be conscious.

    Well, actually, we are machines with the ability to reproduce.
  12. Dec 4, 2003 #11
    Re: Whose work?

    Interesting, but, how can we know that anything is "alive", if there is no known distinction between "living" things and "non-living" things.

    ET(L)? "Evolution theory (Law)"?

    Anyway, don't all of those things that you mentioned apply to a virus? And yet, viruses are not considered "alive". Does this mean that option #3 is the best choice, and we must simply accept that some things are alive by definition, even if we don't think they are?
  13. Dec 4, 2003 #12


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    It's not so much knowing whether 'something' is "alive", rather that the same 'thing' may be 'alive' according to the working definitions of one field; 'not alive' in another field; 'not within the field of study' of a third field; and 'not a relevant label' according to the working definitions in yet a fourth field. I'm certainly no biologist, but it may be that, to virologists, the distinction between 'living' and 'non-living' is not relevant (indeed, it may even be quite a red-herring), and that 'viable' and 'non-viable' are more important. Perhaps to those who study spores, pollen, deep-freeze, etc a different set of distinctions are used; again, 'living' and 'non-living' may actually be confusing, even misleading.

    ET(L) = extra-terrestrial life. As none has been found yet (UFO buffs notwithstanding), working definitions need to be kept in a constant state of review. Personally, it's as exciting to look for evidence of ETL-past (fossil bacteria in rocks in the outflow channels on Mars?) as ETL-present. In the former, a working definition will focus on characteristics and markers for now-extinct life, rather than currently observed reproduction (for example).
  14. Dec 6, 2003 #13

    Very good point, Nereid. Well, I guess, since this is in the Philosophy Forum, my question has more to do with people's personal opinions of whether they can consider something "alive" when there is no working definition for "life". As it is, I can see why professionals in different fields can work with this concept differently.
  15. Dec 6, 2003 #14
    That aside, is a neuron alive? It might be in the scientific sense, but we know it isn't quite aware of its existance and the reason behind it. In that case what is that criteria by which we claim to be alive? Certainly no one would use the term "alive" on a robot as we would on a living human being. Is consciousness the distinguishing criteria? How is it that we should cross the demarcating line from being just a massive functional blob of neurons, muscles, skeleton, and whatnots and land in some place completely different from where we start off from? Why would the synchronised actions of neurons somehow give rise to consciousness when we couldn't say the same for a single neuron? (Surely a neuron couldn't feel.)
  16. Dec 6, 2003 #15


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    Who was it that said they were perfectly capable of thinking 25 contradictory things, even before breakfast (or something similar)?

    I really like the idea of exploring what people's opinions on this subject are, in all its undoubtedly riotous and rich diversity!
  17. Dec 6, 2003 #16
    Re: Why call it "alive"?

    How do I know that I'm alive? That would certainly seem like a good place to start for me.
  18. Dec 7, 2003 #17


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    definition scope and components

    Although this is Philosophy, I think it's important to recognise how limited any definition we're likely to come up with will be, at least in the next 30 to 200 years.

    Our definitions are necessarily limited by our knowledge of what the universe is , and the extent to which we have looked for life.

    Our search for life so far has been in only a tiny, tiny part of the total 'space' of what we otherwise know exists.

    There's the vast expanses of time scales from Planck time (10-43s?) to ~10-23s - as a characteristic lifetime that we know - nothing about.

    At the other end, if some 'living' thing had a lifetime of ~1 billion years (and the equivalent of a heartbeat a year), we'd be hard pressed to notice that it was 'alive', by any definition.

    Life that we know is composed of baryons, a minor but not insignificant component of the universe. What about 'living' things made of the main building blocks of the universe, dark matter? dark energy?? and other minor components - 'living' things in the neutrino regime? photons??

    At the level which matters, all living things we know (and hence the basis - explicit or implicit - of all our working definitions of life) live where only two of the four fundamental forces we know of reign - the electromagnetic and gravitational. Could there be some kind of 'life' among the gluons? Of course, whole Type I civilizations could rise and fall in the lifetime of the most ephemeral hadron and we'd never know it, but for the living things in such a civilization, there'd be all the time in the world.

    Based on our current understanding of physics - particularly the central role of c and the HUP - 'space scale' considerations are essentially the same as the above 'time scale' considerations.
  19. Dec 8, 2003 #18
    I suspect that life somehow begins with consciousness, and the unwillingness to subject oneself to -- and hence exhibiting the desire to avoid -- "pain."
  20. Dec 8, 2003 #19
    Neither is a whale, or a tree, or an insect...did you mean to put "sentient" where you said "alive"? They're not synonymous, you know.
  21. Dec 8, 2003 #20
    Re: Re: Why call it "alive"?

    Indeed. If there is no working definition of "life" then what right do we have to assume that I am but this computer is not? That's pretty much why I started the thread.
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