The Paradox of Life

  • Thread starter RuroumiKenshin
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RuroumiKenshin

Main Question or Discussion Point

I started a thread "The Definition of Alive" on PFs v2.0 and now I have another question pertaining to the definition.
Heredity was said to be the definition of life. Therefore, everything with heredity must be alive. Now, in the thread "Is the Universe Conscious?" the universe does not have heredity, or does it?
Another paradox is:
[/b]
Whenever biologists try to formulate definitions of life, they are troubled by the following: a virus; a growing crystal; Penrose’s tiles; a mule; a dead body of something that was indisputably alive; an extraterrestrial creature whose biochemistry is not based on carbon; an intelligent computer or robot. —William Poundstone, The Recursive Universe
[/b]


But, I have done the honor of actually searching for a more complete definition. And of course, there is the frame work for the definition:
We will be searching for a definition of life that is useful. In order to be useful, the definition should meet the following criteria, so far as possible:

Sufficiency. It should provide the sufficient conditions that enable us to specify whether something is living or not.

Common Usage. These conditions, when applied to "easy" examples, should classify those examples in the same way we normally do. Easy examples include obviously living things such as people, animals, plants, and bacteria; things that were alive but are now dead; and things that we would never normally consider alive, such as rocks, screwdrivers, and growing crystals.

Extensibility. It should be possible to apply these conditions to "difficult" examples with some kind of coherent result. Difficult examples include viruses, mules, fire, simple feedback systems (such as those with thermostats), Gaia, extraterrestrial creatures, and robots.

Simplicity. The definition should be as simple as possible, with a minimum of ifs, ands, or buts.

Objectivity. The definition should refer to measurable and objective properties of the organism. That is, the definition should be specific enough so that different people can be counted on to apply the definition in the same way when they encounter a new "difficult" example.

Once we have determined the sufficient conditions that something must satisfy in order to be considered living, we can go on to ask what additional properties follow from the fact that something is alive. Life may involve certain engineering problems that have only a finite number of possible solutions. Other engineering problems may have a variety of possible solutions, including many that have not been used by any familiar life forms.
To add to heredity, "Virtually all authors who have considered life from the point of view of molecular biology have regarded the property of self-reproduction as the most fundamental aspect of a living organism. —John D. Barrow and Frank J. Tipler, The Anthropic Cosmological Principle"

So, how do we create a definition of life using this given data?
 

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I think it's a continuum - something is more alive than others. While other things are definitely NOT alive. Animals, plants etc. are definitely alive, and more alive than a virus, which in turn is more alive than a growing crystal, which in turn is more alive than a dead horse (not talking about the bacteria etc on the horse).

Anything that reproduces aspects of itself is alive to some extent - crystals, computer viruses, genes, even 'memes'. Everything that produces copies of itself are eventually subjected to selective pressure (only so much environmental 'material' to grow on) because of competition.
 

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