What's the smallest thing that can be alive?

[Math Is Hard]

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.

 

[KaneOris]

I Think Its Obvious, A Single Celled Organism

 

[Math Is Hard]

Tell me why you chose this over a computer virus. Thanks.

 

[wuliheron]

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?

 

[Math Is Hard]

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

 

[Math Is Hard]

Sorry - we posted at the same time. I just saw your argument, wuliheron. I like it.

 

[hypnagogue]

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.

An intelligent being cannot treat every object it sees as a unique entity unlike anything else in the universe. It has to put objects in categories so that it may apply its hard-won knowledge about similar objects, encountered in the past, to the object at hand.

But whenever one tries to program [define]* a set of criteria to capture the members of a category, the category disintegrates. Leaving aside slippery concepts like "beauty" or "dialectical materialism," let's look at a textbook example of a well-defined one: "bachelor." A bachelor, of course, is simply an adult human male who has never been married. But now imagine that a friend asks you to invite some bachelors to her party. What would happen if you used the definition to decide which of the following people to invite?

- Arthur has been living happily with Alice for the last five years. They have a two-year-old daughter and have never officially married.

- Bruce was going to be drafted, so he arranged with his friend Barbara to have a justice of the peace marry them so he would be exempt. They have never lived together. He dates a number of women, and plans to have the marriage annulled as soon as he finds someone he wants to marry.

- Charlie is 17 years old. He lives at home with his parents and is in high school.

- David is 17 years old. He left home at 13, started a small business, and is now a successful young entrepreneur leading a playboy's lifestyle in his penthouse apartment.

- Eli and Edgar are homosexual lovers who have been living together for many years.

- Faisal is allowed by the law of his native Abu Dhabi to have three wives. He currently has two and is interested in meeting another potential fiancée.

- Father Gregory is the bishop of the Catholic cathedral at Groton upon Thames.

The list, which comes from the computer scientist Terry Winograd, shows that the straightforward definition of "bachelor" does not capture our intuitions about who fits the category.

* I inserted the bracketed term here for clarity

 

[kdkdkd]

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!

 

[Math Is Hard]

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!

 

[hypnagogue]

That's funny, I'm actually in the process of reading that book myself. 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 ). It's really interesting to see how such a seemingly logic-defying kind of behavior naturally emerges from a relatively simple computational setup.

 

[Math Is Hard]

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

 

[Philocrat]

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

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.

 

[False Prophet]

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 definitely alive.

I've heard people say a colony of bees is alive (as its own single entity) but I think that's bologna.

 

[123rock]

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!

I think we're much smaller than the Earth.

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 definitely alive.

I've heard people say a colony of bees is alive (as its own single entity) but I think that's bologna.

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

 

[Math Is Hard]

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.

 

[Math Is Hard]

123Rock, where is your definition from, just out of curiosity?

 

[Philocrat]

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

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.

 

[selfAdjoint]

Such programs have been written. See "genetic programming" where the instruction set is subjected to random variation and selection.

 

[hypnagogue]

In this sense, we could say that the system in which such a program is installed is self-aware and conscious.

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.

 

[Imparcticle]

Trees don't move, yet they're living things

Yes, they do move. If they grow, then surely they move [towards sunlight].

 

[Imparcticle]

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.

The manner in which one is self aware/conscious is based on a set of criterion/instructions that, in the context which you have presented, are programs. According to various studies reported in SCIAM concerning psychoanalytical theories, conscious behavior is regulated by subconscious programs or instructions. Furthermore, such subconscious motivations provide a basis to more advanced behavior.
How would a conscious being/system rewrite an instinctive instruction? To what extent do you propose a system rewrite an internal instruction?

 

[Philocrat]

The manner in which one is self aware/conscious is based on a set of criterion/instructions that, in the context which you have presented, are programs. According to various studies reported in SCIAM concerning psychoanalytical theories, conscious behavior is regulated by subconscious programs or instructions. Furthermore, such subconscious motivations provide a basis to more advanced behavior.
How would a conscious being/system rewrite an instinctive instruction? To what extent do you propose a system rewrite an internal instruction?

Awareness about awareness is just a set of priority visual levels. I am not a very good fan of the term 'subconscious', for deprioritised visual levels are often mistakenly qualified by this term. Things that the boby can do without the upper conscious-level visual attention are deprioritised, and self-discrimination and reprogramming in response to the intervening contents of the external world is one of such things. In terms of a computer program, I am suggesting that the instruction set be made fully dynamic. How this can be done is matter of continuous technological reviews.

 

[kdkdkd]

I think we're much smaller than the Earth.

we originated because of earth. i consider humans to be parasites. "living" doesn't quite suit us. Earth the the smallest self sufficient being in the universe we know.

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

movement can be through the roots that penetrate the ground or the branches that spread out.
it doesn't have to be translatory motion

 

[Math Is Hard]

we originated because of earth. i consider humans to be parasites. "living" doesn't quite suit us. Earth the the smallest self sufficient being in the universe we know.

but even a parasite is a living thing. the lowly flea can have the status of being alive or being dead. same goes for bacteria and viruses.

 

[zhana]

Tell me why you chose this over a computer virus. Thanks.

A computer virus,eh?You are probably thinking of biological viruses flying all over around us ,not the computer ones.
Yes,I consider such ones alive.
Question for others :what about prions?I don't considered them alive.Just a dangerous substance.

 

[hypnagogue]

earth the the smallest self sufficient being in the universe we know.

Earth wouldn't be good for much at all if it weren't for the sun.

 

[Math Is Hard]

A computer virus,eh?You are probably thinking of biological viruses flying all over around us ,not the computer ones.
Yes,I consider such ones alive.

No, I actually specifically meant a computer virus when I asked that question. It was something Stephen Hawking said in a lecture that got me thinking about this:

from http://www.hawking.org.uk/lectures/life.html

"A living being usually has two elements: a set of instructions that tell the system how to sustain and reproduce itself, and a mechanism to carry out the instructions. In biology, these two parts are called genes and metabolism. But it is worth emphasising that there need be nothing biological about them. For example, a computer virus is a program that will make copies of itself in the memory of a computer, and will transfer itself to other computers. Thus it fits the definition of a living system, that I have given. Like a biological virus, it is a rather degenerate form, because it contains only instructions or genes, and doesn't have any metabolism of its own. Instead, it reprograms the metabolism of the host computer, or cell. Some people have questioned whether viruses should count as life, because they are parasites, and can not exist independently of their hosts. But then most forms of life, ourselves included, are parasites, in that they feed off and depend for their survival on other forms of life. I think computer viruses should count as life. Maybe it says something about human nature, that the only form of life we have created so far is purely destructive. Talk about creating life in our own image. I shall return to electronic forms of life later on."

Question for others :what about prions?I don't considered them alive.Just a dangerous substance.

Good question.

 

[Philocrat]

No, I actually specifically meant a computer virus when I asked that question. It was something Stephen Hawking said in a lecture that got me thinking about this:

from http://www.hawking.org.uk/lectures/life.html

"A living being usually has two elements: a set of instructions that tell the system how to sustain and reproduce itself, and a mechanism to carry out the instructions. In biology, these two parts are called genes and metabolism. But it is worth emphasising that there need be nothing biological about them. For example, a computer virus is a program that will make copies of itself in the memory of a computer, and will transfer itself to other computers. Thus it fits the definition of a living system, that I have given. Like a biological virus, it is a rather degenerate form, because it contains only instructions or genes, and doesn't have any metabolism of its own. Instead, it reprograms the metabolism of the host computer, or cell. Some people have questioned whether viruses should count as life, because they are parasites, and can not exist independently of their hosts. But then most forms of life, ourselves included, are parasites, in that they feed off and depend for their survival on other forms of life. I think computer viruses should count as life. Maybe it says something about human nature, that the only form of life we have created so far is purely destructive. Talk about creating life in our own image. I shall return to electronic forms of life later on."


Good question.

Thanks for pointing us to Hawking's lecture. A document of monumental Magnitude! It contains materials of startling consclusions and profound implications ...several of which are compatible with the catalogue of stuff that I carry around in my head. But I have a purely logical issue about his conclusion on the possibility of life in other parts of the the universe. I think, on a purely logical term (without any interference of hard-headed mathematics), the probability of life elsewhere is higher than suggested.

On the issue of why we have not yet been visited by aliens from outer space, I agree with all the likely reasons given. But a far more subtler alternative reason is not ruled out either: that they have been already, and are microscopic and superior, thus using superior technology to hold the human race on a string...like puppets on a string! Human beings are obsessed with big things, so we naively rule out this option.

 

[Philocrat]

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.

---------------------------------------------
My system crashed last night while trying to respond to you. Anyawy, here is that response, if it works this time around:
---------------------------------------------

That is only if you join the bandwagon of believing that:

1) Consciousness is mysteriously over and above the physical

2) Consciousenss is Independent by (a) merely intervening with the physical body, and (b) surviving the death of the material body.

3) Consciousnes is Functionally superior to the body

4) Consciousness is something that only human beings have.

Well, (1) - (3) are keeping members of the popular bandwagon very busy, but equally some philosophers and many researchers on the subject do not rule (4) out. Infact, there is nothing which rules out the possibility of consciousness in other intelligent systems. Computer, for example, is already an intelligent system, it's just a matter when it is going to become conscious, given that we knew what the proper definition of consciousness is in the first place.

 

[hypnagogue]

That is only if you join the bandwagon of believing that:

1) Consciousness is mysteriously over and above the physical

This is the only criterion of yours that is relevant to my post, although it is somewhat misleadingly stated. A more accurate depiction of this stance would be to say "Phenomenal consciousness does not logically supervene on the physical." The claim is not that consciousness is independent of the physical facts, but rather that a complete specification of the physical facts does not entail the existence of phenomenal consciousness. Any purely physical description of the brain is logically consistent with the absence of phenomenal consciousness. Likewise, any functional description of a self-modeling system is logically consistent with the absence of phenomenal consciousness.