[wolram (OP)]

In my view life, must mean, (some thing) able to reproduce and evolve, inteligent life is quite
different, how do (we) define intelligent, on another world some thing akin to a tree stump could be pondering if humans are alive.

A born optomist

[DoctorBeaver]

quote:Incorrect? How can a definition be incorrect – it is whatever we choose it to be. We may choose to change a definition, but that does not make either the new or the old definition incorrect per se.

A definition can be incorrect if it is based on incomplete knowledge. Someone in rural England in the middle ages may have defined a human being as looking very much like himself. He would quite probably have included his own skin colour. His definition would therefore have been based on an incorrect assumption; i.e. that all humans are the same colour.
Definitions must change if an increase in pertinent knowledge shows them to be wrong.

[another_someone]

quote:Originally posted by DoctorBeaver

A definition can be incorrect if it is based on incomplete knowledge. Someone in rural England in the middle ages may have defined a human being as looking very much like himself. He would quite probably have included his own skin colour. His definition would therefore have been based on an incorrect assumption; i.e. that all humans are the same colour.
Definitions must change if an increase in pertinent knowledge shows them to be wrong.

Ignoring the fact that people of different skin colour have been in Europe, and Europeans have been around the perimeter of North Africa, for some considerable time; but more pertinently, if the definition of 'human' excluded blacks, then that was the correct definition for them (just as their definition of 'girl' might be gender neutral, while ours excludes young males – which is the right definition, and which is the wrong definition).

This can lead to some anomalies, as we still retain phrases and written documents from past eras that assume a definition of the words used at the time the phrase of document was first created, but the definition of the words has changed, giving and incorrect modern interpretation of the phrase or document.

Ofcourse, definitions are created to support the contemporary knowledge base, and as knowledge changes, so does the meaning of words.  On another thread, we are discussing viruses, and assume some knowledge of what a virus is, but that knowledge is very different to the knowledge that someone in ancient Rome would have known about disease, and thus we have interpreted the word virus to have a meaning totally alien to the meaning the ancient Romans would have used it for.  Does this mean that there definition for the word virus was incorrect?

George

[DoctorBeaver]

quote:Ofcourse, definitions are created to support the contemporary knowledge base, and as knowledge changes, so does the meaning of words. On another thread, we are discussing viruses, and assume some knowledge of what a virus is, but that knowledge is very different to the knowledge that someone in ancient Rome would have known about disease, and thus we have interpreted the word virus to have a meaning totally alien to the meaning the ancient Romans would have used it for. Does this mean that there definition for the word virus was incorrect?

I'm not sure what "virus" was supposed to mean to a Roman so I can't really comment on that. It's quite possible that the word was adopted for what we now call a virus because a word was needed whose existing definition meant something similar. Taking an existing word and applying it to something new does not change its original definition. Take the word "gay". It still means "happy" as well as "homosexual"; its original definition has not changed, another definition has been added.
I think that is a very different thing to sticking rigidly to a definition when contemporary knowledge shows that definition to be incomplete or incorrect.

Brand new forum
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More than just science

[another_someone]

quote:Originally posted by DoctorBeaver
I'm not sure what "virus" was supposed to mean to a Roman so I can't really comment on that. It's quite possible that the word was adopted for what we now call a virus because a word was needed whose existing definition meant something similar. Taking an existing word and applying it to something new does not change its original definition. Take the word "gay". It still means "happy" as well as "homosexual"; its original definition has not changed, another definition has been added.
I think that is a very different thing to sticking rigidly to a definition when contemporary knowledge shows that definition to be incomplete or incorrect.

Virus was a word the Romans used to refer to a toxic slime.

The point is, to say that our definition of life will ever be proven wrong, not merely superseded by a definition that is more useful to later generations, but no more or less right or wrong that anything we use it for today, we first need a reference point against which we can judge what life should mean, and then later judge that it does not mean that.  Would you like to propose a reference point against which we can judge the definition of life?

George

[another_someone]

quote:Originally posted by wolram

In my view life, must mean, (some thing) able to reproduce and evolve, inteligent life is quite
different, how do (we) define intelligent, on another world some thing akin to a tree stump could be pondering if humans are alive.

A born optomist

Sounds reasonable, but does have some problems.

Is a man who has had a vasectomy (or a woman beyond menopause) dead?  They are certainly not able to reproduce, or evolve.

A star is able to reproduce (not sure if it can be regarded as evolving or not) – would that make a star a living entity?

Are viruses living?  Many biologists do not regard viruses as living because they cannot copy their own DNA, but require another living cell to do the copying for them; nonetheless, they do effectively reproduce, and certainly do evolve.

What about houses – do they reproduce and evolve?  Like the virus, they do not themselves have the capacity to replicate, but with the help of other living organisms (namely human beings), they do reproduce and they do evolve.  Yes, I know, this example may seem absurd; but if we come across some novel process in some far off place, who is to say what is absurd and what is not?

George

[neilep]

Fire.

It's birth is a spark. It grows, it spreads, it has offspring and dies, but it's clearly not alive.

But, there may be life out there which resembles fire but has one or two extra ingredients that afford it sentience. Should we discover it then we would have no choice but to deem it alive, despite it not meeting our criteria for our definition of life.

PLEASE, I don't want to turn this into a religious thread, but would religious people consider God alive I wonder ! Ok , they might say that WE are Gods children but what about the other facets of ' life '...anyway..maybe this paragraph is for a different thread.

I think the term 'life' is malleable and may have to be altered with precursors to accommodate life in all its forms and states that do not apply to our current definition.



Men are the same as women, just inside out !

[rosy]

quote:has one or two extra ingredients that afford it sentience

I think you're setting the bar a bit high here Neil. I wouldn't normally call an amaoeba sentient.

[another_someone]

quote:Originally posted by neilep

Fire.

It's birth is a spark. It grows, it spreads, it has offspring and dies, but it's clearly not alive.

Fire spreads (i.e. it grows), but it does not reproduce (i.e. it does not create distinct and separate replicate units of itself), and for this reason, it cannot be regarded as evolving (i.e. creating offspring that are separate from the parent, that are similar to the parent, but that are nonetheless different to the parent, and where the difference is subject to selective advantage and disadvantage that will cause inheritable changes in future offspring).

Whether stars fall into this category is open to debate (stars certainly do create distinct and separate replicate units of themselves, but do they contain inheritable traits that are subject to selection?), but houses do indeed fall into this category (a change in house design, if successful, can spawn new similar houses to be built).

Previous generations would have considered fire to be alive, but then they did not base life upon the notion of reproduction or evolution, but on being able to respond to the environment around it (fire will be effected by its environment, and so is quick-silver, hence its name).

But, no-one has answered my question, that if life is defined by its ability to reproduce, does the inability of an individual to reproduce mean we have to define that individual as not being alive?

quote:

But, there may be life out there which resembles fire but has one or two extra ingredients that afford it sentience. Should we discover it then we would have no choice but to deem it alive, despite it not meeting our criteria for our definition of life.

I think Rosy has answered the question on sentience.

George

[neilep]

Yes you're right (Rosy and George.....hmmm..sounds like a kids TV show !!) sentience does not make for life....sorry *bites knuckles and eats humble pie*...that was clearly the wrong thing to say...

...however, I would say fire does make offspring...sparks from it produce new flames and hence offspring.

Someone who can no longer produce children is still clearly alive and therefore does indeed subscribe to perhaps an alternate definition for the word life, be it through a sterilization process or just plain old age.................

[another_someone]

quote:Originally posted by neilep
...however, I would say fire does make offspring...sparks from it produce new flames and hence offspring.

I would question your notion of offspring because I would question the notion of a uniquely identifiable fire (fires can merge as well as split, so one cannot regard as fire as a self contained organism with defined boundaries that would allow one to unambiguously define a parent and a child).

That aside, fir will fail Robin's (wolfram) evolution test – fires have no variable inheritable traits that might be the basis for evolution.

That having been said, evolution is a relatively modern concept, and one has to ask whether it is appropriate to base a definition of life on a presumption of evolution (a notion that some religious groups would I think not accept – although I don't think they would have any problem with the notion of inheritable traits as such).

quote:
Someone who can no longer produce children is still clearly alive and therefore does indeed subscribe to perhaps an alternate definition for the word life, be it through a sterilization process or just plain old age.................

So, do we now have two definitions for life, or will this alternative definition of life suffice on its own, and can we discard the concept of reproduction as a basis of the definition of life?

Would you like to hazard a guess as to what this new definition might be?

That having been said, and a moment of reflection, I don't think the above obstacle is as much of a problem as I originally proposed – we simply have to reverse our definition of life – rather than saying that life is that which is capable of reproduction, we could better say that life is the product of reproduction (now why didn't you think of that – do I need to carry both sides of the argument myself [])

Although, even the above redefinition has a problem with how do we exclude corpses from our definition (although, within some limitations, I think there may be ways around that, although those ways might have a problem with defining the exact moment of death).

George

[wolram (OP)]

Someone who can no longer produce children is still clearly alive and therefore does indeed subscribe to perhaps an alternate definition for the word life, be it through a sterilization process or just plain old age.................

May be one can not adjudge an unknown individual as alive, if we can not
communicate with it, it shows no sign of reproduction, and does not
consume food , It would have to be a community of (aliens)
we study, if they did none of the above it would be difficult to
call them alive.

A born optomist

[another_someone]

quote:Originally posted by wolram
May be one can not adjudge an unknown individual as alive, if we can not
communicate with it, it shows no sign of reproduction, and does not
consume food , It would have to be a community of (aliens)
we study, if they did none of the above it would be difficult to
call them alive.

I agree about whether we are able to judge whether something is alive or not – but that is different from how we define whether something is alive or not.  It may well be the case that we cannot determine whether an individual meets that definition without seeing a large number of individuals, but nonetheless, in order to be able to say something is alive, we must be able to say that each and every individual meets the definition of being alive (it's no good simply saying that because 60% of those we see are demonstrably alive, therefore we define – not assume, but define - that they are all alive).

OK, I would put forward the following tests for something to be regarded as living:

a) It must be able to modify its environment in a way that assists its survival (even bacteria can do this).

b) It must be the product of imperfect reproduction.  The nature of the imperfections must be themselves inheritable, and relevant to the ability of the organism to survive.  This logically leads to a need for a clearly defined parent child relationship (this would exclude fire).

c) Not really a separate matter, since it is a natural consequence of the above conditions, the organism must have clearly defined bounds (you must be able to say throughout the life of the organism that you can state what is a part of the organism and what is not a part of the organism).

d) In order to settle problems with defining the bounds of an organism, particularly with regard to organisms that share the same genetic code (e.g. identical twins or plants grown from cuttings), I would say one should be able to find a way of killing an entire organism by attacking only one part of an organism (if you remove a vital organ from a twin, you will kill the entire individual, but not their twin sibling).


With regard to Niel's question pertaining to God, God is (in the Judeo-Christian-Islamic traditions) perfect, and not the product of reproduction (if one looked at Gods in the classical Greek pantheon, one might see a different picture).

OK, first question – do people have any major problems with the above definitions.

If the above is agreeable, how would you go about testing whether a particular entity met those criteria or not?

George

[neilep]

Phew George !!..You don't arf give food for thought and force others to use their brain !! (you need a new contract !!)...I'm going to sit back for a while, twiddle my thumbs ** before I accidentally delete this thread also !!




**actually this means I'm going to wait until someone else answers !!

Men are the same as women, just inside out !

[wolram (OP)]

b) It must be the product of imperfect reproduction. The nature of the imperfections must be themselves inheritable, and relevant to the ability of the organism to survive. This logically leads to a need for a clearly defined parent child relationship (this would exclude fire).

I am not sure about this, there may be a way to (clone) that is natural
to some alien life form, not very good for enviromental adaptation, but
if said enviroment is stable over large time scales evolution may be
un neccesary.

A born optomist

[another_someone]

quote:Originally posted by wolram


b) It must be the product of imperfect reproduction. The nature of the imperfections must be themselves inheritable, and relevant to the ability of the organism to survive. This logically leads to a need for a clearly defined parent child relationship (this would exclude fire).

I am not sure about this, there may be a way to (clone) that is natural
to some alien life form, not very good for enviromental adaptation, but
if said enviroment is stable over large time scales evolution may be
un neccesary.

A born optomist

The only stable environment is a sterile environment (i.e. a dead environment).

More directly, if we find a life form that is incapable of evolution, how would you suggest the life form evolved in the first place (unless we accept intelligent design as a mechanism)?

George

[wolram (OP)]

More directly, if we find a life form that is incapable of evolution, how would you suggest the life form evolved in the first place (unless we accept intelligent design as a mechanism)?

No ID, is not in my book [] i do find it interesting trying to define
life, and the possible forms it may take, even if there is life other than ours in the u, i guess any advantage to humanity would require higher intelligence, or least a life form that can develop thinking on
a par with ours.

A born optomist