I was surprised to learn that there is no universally agreed definition of life:


The definition of life is growing in importance. We want to know when human life begins for lots of ethical, legal, and religious reasons. We want to know that if we find something crawling around on Mars it can be classified as life. As artificial intelligence evolves, we want to know when to start granting androids rights. And if a human is in a coma, we want to know at what point that individual could be considered no longer alive.

So I was noodling with a functional definition of life that aims to solve our current and future ethical dilemmas. How about defining life as any discreet entity with the following qualities:

  1. Potential to feel pain.
  2. Potential to learn.

This definition keeps our future androids from getting full legal rights, since they can't feel pain. And it would let you pull the plug on anyone who doctor's say has no potential to ever feel pain or learn again. So far, so good.

One thorny issue is that life would begin at conception by this definition. It would be a separate argument as to whether the woman carrying the life has a right to terminate it while it is still in the early potential phase.

My definition keeps a virus from being considered life. And plants too, I think. That feels right. I don't think lettuce needs to be "alive" any more than my watch.

I haven't thought this idea through. I'm just throwing it out there for consideration.

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Jan 26, 2009
I don't think this definition will work very well. There are lots of animals (fish, insects, etc) which are generally considered to not feel pain (although there is debate on the issue). It seems like you're creating more problems than you're solving with this definition.
Jan 26, 2009
Defining life is so difficult because we are not really alive in the first place. We have no soul, no free will, no spirit. I haven't been able to bend even a single law of thermodynamics. We are no more alive than a rock. (our chemicals just react faster at current tempertures)
Jan 26, 2009
Characteristics of life: (1) Consciousness (including ability to feel pain, (2) Reasoning (capacity to solve problems, or learn), (3) Self-motivated activity, (4) Capacity to communicate, (5) Self-aware.
Jan 26, 2009
One other thing that came to mind about attempting to define the nature of life, especially in time measurements of universal ages. We tend to believe that the universe is infinite, and therefore in an infinite medium, anything can be possible, per definition. That is to say, we have a belief about infinity that states if we give a million monkeys a million word processors and an infinite amount of time that they will randomly come up with the complete works of William Shakesphere. Well what about all the Billion-Billion other groups of a million monkeys with their word processors who didn't quite get it?

I mean, what do you suppose it would be like to be living in the universe where the Million monkeys got everything right except the very last word, like, "The Exd". The universe wouldn't ever feel quite right if that was your perception of life. Something is always a little off, but you can never quite put your finger on it...
Jan 26, 2009
Sorry Scott, you can't use pain as a criterion. Why? CIPA. You wouldn't deprive this poor girl the dignity of being called "alive," would you? http://www.msnbc.msn.com/id/6379795/?GT1=5740

Also, pain could easily be programmed into silicon-based life (androids), as well as deprogrammed from carbon-based life forms (humans).

Using the "ability to learn" would also be too difficult to use. Someone in a coma may not have the ability to learn. But the cells in her body could still learn how to detect new forms of disease and mount an immune response to them. Would you give a white blood cell priority over a human in a coma?

I think your definition would have to have more to do with level of sentience and you're not going to be able to avoid giving artificial life rights, if it ever evolves to a level of sentience where we would normally grant one human-level rights. Sorry.
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Jan 26, 2009
Oh, and thankyou to richardhclark for invalidating one of the classic evidences that God does not exist in his post where he seems to imply that God does not exist. (I mean the one that he would have to stop bad things from happening to good people, which he would not have to do if he did not consider us to be alive.)
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Jan 26, 2009
The issue isn't about defining life. It's about trying to understand why issues like abortion, stem cell research etc. are imagined to hinge on any random definition of life. Or - not unrelatedly - humanity. I'm not sure why it matters to whether we fire up some imaginary argument to determine whether a cell or a bunch of cells or an embryo is or isn't life or is or isn't humanity. I tend to side with Russell.
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Jan 26, 2009
I have to protest this blog entry since it is simply merely an attempt to define life to be whatever a vegitarian does not want to eat. Not being a vegitarian the desire to define life in this way simply doesn't make sense to me.
Jan 26, 2009
The ability to determine if something is alive or not is entirely subjective based upon any current definitions that we as a species can come up with. The criteria:
Potential to feel pain.
Potential to learn.
is entirely subjective. I can train plants to grow around a fenceline and therefore become a hedge. This demonstrates learning. Learning is accomplished by changing current !$%*!$%*!$%*! of the static entity, and it adapting. However, I have not seen anything, ANYTHING, that is not in a state of change. As most of us know, we learn to welcome change, although change in most instances is accompanied by some measure of uncomfortableness. How uncomfortableness is perceived by the entity that is changing can be anything from enjoyable to extremely painful. However, life continues regardless of this. I suppose one could say that things change or die, but even in that there is change, movement and demonstration of life. There are serious and deep ramifications in this line of thought.

Most people on earth believe in some sort of all-knowling, all-seeing supreme being that is timeless or has a consciousness that can be measured in universal ages instead of years, that is if we had a way to measure life that moves at the speed of univeral ages. Suppose for a minute that such an entity exists. If such entites have a discussion such as we are having right now, they would not consider us alive, because accourding to their perception, the entire birth and death of our sun would occur in such a small amount of thier time that by the time the entity typing the next letter in a blog discussing what life is, the entire Milky Way Galaxy would have been born and then dissolved into nothingness, and all of human history [assuming we are the center of the universe as our beliefs tend to indicate] would be completely lost on such !$%*!$%*!

No, who is to say whether or not a computer, for instance, lives an entire life of existence that we cannot even fathom or even measure between reboots? Perhaps to a computer's way of perception, each life between reboots might be a reincarnation of sorts. [Have you seen TRON?] A tree that has lived over 3,500 years has an experience of much more human history than any of us can possibly remember, and yet the entity still experienced it, even though it has no method to communicate that experience to us, right now, today, except by it's presence.

Perhaps the real issue is, I defy you to define something that is not alive, and describe the criteria that could be used repeatedly to apply this definition in an ongoing manner.

I apologise to any with fixed ideas about the way things are for the Zen of this post, as I know it gives change to your ideas, and therefore some measure of pain. These changes might cause some pain or anxiety to those inflexible to adapt to what actually is the reality of universal change. Such is the nature of evolution and entropy.

So, simply put, I suppose I am apologising for God stepping on your beliefs about what actually God is.
Jan 26, 2009
Like others have pointed out you now have the problem of defining 'pain'.

I wonder if the creator should own the rights to his product till the product can claim otherwise. Whoever creates an android can choose to terminate it unless he programs the android to claim its ownership. This becomes a !$%*!$ issue when parents kill children not old enough to understand this concept. But then I don't really buy into this sanctity of life nonsense so that really doesn't bother me.
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Jan 26, 2009
As a hologram I am acutely aware that pain is merely a false memory of another hologram having interacted with me in some unpleasant fashion.

That being said, I do share your latent bias for moist robots over animatronic robots.

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Jan 26, 2009
I was growing up in freshly post-soviet country, still using soviet text books in schools at that time. There was a marxistian definition of life in our biology text books (though I am positive not by Marx himslef):

Life is a condition when proteins can multiply.

BTW only
Jan 26, 2009
I can't imagine that definitions of life will matter much to people pushing social and religious policies.
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Jan 26, 2009
Well, considering the fact that we're all holograms, we aren't really feeling pain, so technically we aren't alive either..
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Jan 26, 2009
Why wouldn't androids be able to feel pain?

Humans sense things that cause damage as pain, so why wouldn't an android be able to do the same?

Second of all, the definition of learning is not good: is learning just anything that solves a pattern, or must it be able to be self-referencing (i.e, be able to be expressed by the entity in language)

And are androids who share central components of their brain separate !$%*!$%*!
Jan 26, 2009
The one distinguishing feature of "life" is its complexity / entropy. Ability to feel pain / ability to reproduce / carbon-based or not etc. do not really matter. What distinguishes life forms from rocks is their complexity. At some point artificial intelligence will be more complex than our brains.
Jan 26, 2009
How about defining sentience as "Having the capacity to understand that wikipedia is only as good as the articles it references, and should never be implicitly trusted".

For something to qualify as alive it must exhibit Reproduction, Selection, and Mutation. Let me know if you find anything that doesn't. Defining the point where something becomes human is a different question entirely.
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Jan 26, 2009
Did you mean discreet (prudent) or discrete (separate)?
If life included only discreet !$%*!$%*! half the human race would be disqualified.
Jan 26, 2009
My boss-

1. Feels no pain, no matter what.
2. Has absolutely no potential to learn.

Is he dead? If yes, then we are surely confirming the existence of ghosts !

What say Scott?
Jan 26, 2009
Living in the rural southeast, I am almost certain a number of my neighbors have no potential to learn anything. I really like this definition because I no longer have to try to avoid these neighbors when they are crossing the street any more than I would try to avoid a large, walking head of lettuce. This definition does put a hindrance on higher learning, since the closer one gets to learning everything the closer that person is to no longer being alive by definition.
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