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Alive?

  1. Sep 22, 2004 #1

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    What is the smallest, simplest thing that can be considered to be "alive"?
    Bacteria, maybe? A computer virus?
    I would like to hear your thoughts on this.
     
  2. jcsd
  3. Sep 22, 2004 #2
    I Think Its Obvious, A Single Celled Organism
     
  4. Sep 22, 2004 #3

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    Tell me why you chose this over a computer virus. Thanks.
     
  5. Sep 22, 2004 #4
    Current computers cannot reach the nano scale of mitochondria and viruses, so computer viruses don't measure up.... or down as the case may be.

    The definition of living things is debatable, so exactly what you might consider alive and dead is up for grabs. Viruses are considered somewhere in the middle, between alive and dead. When dormant, they are considered dead. They can't move around on their own, they can't reproduce on their own, and theoretically they can last for millions of years. Are they alive or merely so many interesting chemical reactions?
     
  6. Sep 22, 2004 #5

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    Maybe I can clarify. If something can be categorized as alive, what requirements must be met?
    I am thinking:
    1) Must contain an instruction set for its own survival
    2) Must contain an instruction set to reproduce
     
  7. Sep 22, 2004 #6

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    Sorry - we posted at the same time. I just saw your argument, wuliheron. I like it.
     
  8. Sep 22, 2004 #7

    hypnagogue

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    To expand a bit on what wuliheron said, life is in an intuitive, fuzzy concept. This is what allows exact definitions to be debatable, and also what allows us to consider something like a virus somewhere inbetween. We can contrive various exacting, rigorous definitions to try to capture our intuition, but really the important thing to take home is that the intuition preceeds the definition.

    In actuality, many (if not most) of our categorical concepts tend to work this way. Here's an excerpt from Steven Pinker's How the Mind Works that may be illuminating.

    * I inserted the bracketed term here for clarity
     
    Last edited: Sep 22, 2004
  9. Sep 22, 2004 #8
    i guess the smallest, simplest thing that IS alive is our earth. if you think beyond the boundaries, earth is a microcosm in the endless universe. It is the simplest because just 2 things on earth are sufficient to aid life, water and oxygen. Probably presence of human emotion complicates the issue!
     
  10. Sep 22, 2004 #9

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    Hyp - that's so bizarre that you referenced the Pinker book. I have been sort of lazily perusing this book in the evenings before I go to sleep. I am going to look into these pieces. (Maybe this is what got me started on this topic subconsciously).
    Thanks!
     
  11. Sep 23, 2004 #10

    hypnagogue

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    That's funny, I'm actually in the process of reading that book myself. :smile: If you haven't reached it yet, Pinker goes into a nice account of how this kind of fuzzy thinking / categorizing might be instantiated in the neural circuitry of the brain about 100 pages in (I was going to say "in the middle of chapter 2," but that doesn't seem to do justice to how long these chapters are :tongue:). It's really interesting to see how such a seemingly logic-defying kind of behavior naturally emerges from a relatively simple computational setup.
     
  12. Sep 23, 2004 #11

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    I have been skipping around the book a little bit, but I am going to go back and concentrate on chap 2 some more. Fuzzy logic is amusing to me because (hard) logic-defying behavior is exactly what computer programmers don't want from a program!

    I became interested in his book because I plan on getting my B.S. in cognitive science. Unfortunately, it's a very unpopular major :frown:
     
  13. Sep 25, 2004 #12
    Don't worry about cognitive science not being popular....it will soon be. But while on this course, you must pay absolute attention to the following fundamental areas:

    1) THE INSTRUCTION SET THEORY

    This is the theory which says that no one can viloate the number of instructions in a given computer program because the number is fixed, and therefore internally non-modifiable by the program conerned, except by an external agent such as the programmer who wrote the program, or a computer virus that might add or remove instructions from it, or another programmer commissioned to improve the original program. Your quest, therefore, must or should be to violate this theory.

    MY STANDARD ARGUMENT IS THIS: Anyone who can violate this theory would make any system (computer, robbot, etc.) holding such a program not only to think, learn and understand things but also to be fully conscious.

    2) THE SCOPE AND LIMITS OF CONSCIOUSNESS

    By all means listen to what your tutors say, but you must unfailingly keep an open mind on this. The current commonly held belief is that (1) Consciousness is limited only to the humans, and (2) Conscousenss is something over and above the physical. Your reaserch, if you study up to that level, should concentrate in disproving both. Your research should show that not only can other things be conscious but also that, through structural re-engineering, they can get smarter and smarter. Some philosophers have gone a step further by arguing that even consciousness in a machine is not ruled out either.

    MY ARGUMENT IS THIS: If (1) is disproved, then (2) is automatically disproved. Hence, if I were you I would ignore (2) and concentrate on (1), not unless something subsequently turns up for this to be construed otherwise.
     
    Last edited: Sep 25, 2004
  14. Sep 26, 2004 #13
    The dictionary is way too vague about what alive means.

    I think fire is alive. It has the following characteristics:

    It eats.
    It moves.
    It grows.
    It reproduces.
    It is compelled to survive until it no longer can.

    A computer virus is attacking computers only like it's programmed to do, so it's no more alive than that stupid paperclip in Microsoft Word. I believe real viruses, like influenza, are definately alive.

    I've heard people say a colony of bees is alive (as its own single entity) but I think that's bologna.
     
  15. Sep 26, 2004 #14
    I think we're much smaller than the Earth.


    Trees don't move, yet they're living things.
    Definition of a living thing:
    1) It can reproduce
    2) It is separated by a semipermeable membrane from the rest of the world
    3) Can grow
     
  16. Sep 26, 2004 #15

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    Very interesting thoughts from everyone. Regarding the Instruction Set Theory, is this basically saying that the program cannot self modify and change, add or delete any of the original lines of code?

    Fire is something I never would have considered. But how can this argument be knocked down? I can't come up with a good line of attack.
     
  17. Sep 26, 2004 #16

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    123Rock, where is your definition from, just out of curiosity?
     
  18. Sep 26, 2004 #17
    Yes, in the strictest sense of self-modification. Not a program being instructed to self-modify in response to the programmer's intended intervening events. When a computer program becomes self-aware of its own internal syntactical, symantical and instruction set limititations, and begins to rewrite its internal structures and modules independent of the original programmer who wrote it, then this would amount to a proper violation of the Instruction set theory (IST). In this sense, we could say that the system in which such a program is installed is self-aware and conscious.
     
  19. Sep 26, 2004 #18

    selfAdjoint

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    Such programs have been written. See "genetic programming" where the instruction set is subjected to random variation and selection.
     
  20. Sep 26, 2004 #19

    hypnagogue

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    Only if you're assuming a very impoverished sense of the word 'conscious' (ie, not the philosophically interesting sense) could you make a statement like that so flippantly. The problem of consciousness is not synonymous with the problem of a system modeling itself.
     
  21. Sep 26, 2004 #20
    Yes, they do move. If they grow, then surely they move [towards sunlight].
     
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