For those who think life is rare

[Chronos]

I don't think many would dispute that environmental pressure plays a central role in evolution. Climate altering events, like ice ages, are especially hard on critters who were most exquisitely tuned to the former habitat. In certain isolated habitats, like oceanic volcanic vents at great depths, there are creatures that have survived for hundreds of millions of years essentially unchanged. On the other hand, the universe is pretty dangerous place. I would be quite surprised if there are any hospitable planets anywhere that have not been traumatized as much, if not more than our own.

But, I would have to admit to being a maverick by mainstream evolutionists. Intelligence is a fairly unique adaptation. It is not driven by the environment, rather it is driven by competition between individuals of the same species, as well as competition with other species within its ecosystem. Smart rabbits produce more rabbits, dumb rabbits produce more wolves. It's pretty much the difference between whose kids you end up feeding at the end of the day. A smart critter gets more bang for the buck out of its natural abilities than its dumb buddies. Once nature evolved brains, it seems inevitable she would experiment with different sizes. The trick is in not going extinct while traveling the long, torturous road to achieving human-like intelligence. It currently appears there are few, if any just like us 'out there' and none so far advanced that their presence is immodestly obvious.

 

[turbo]

So true! Adaptive behavior can trump natural selection, and that's where the value of intelligence shines. We humans are not particularly strong, or fast, or able to stand extremes of heat or cold, but the adaptive behaviors that we have adopted have given us unprecedented geographic range. The Inuit live in climates that would kill most humans without the knowledge and skills passed down from countless generations.

My predeliction to view and photograph astronomical objects in -20 F weather has grown out of my own experience that these bitter nights often have steady skies, and the learned experience that you must emulate the heat-conserving behaviors of ice fisherman and other cold-weather nuts, and then double that, if you expect to keep your eye glued (frozen is a better term) to a guidescope ocular for 20-30 minutes without moving. My wife says that when I observe in the winter, I'm bigger than the Michelin man. I am "relatively" comfortable in an environment in which an unprepared human would perish in short order.

There is no way that a human could be genetically modified to handle short-term extremes like this - the only way to handle the extremes is to adopt adaptive behaviors. Simple organisms can survive extremes in temperature by developing the ability to go into stasis and conserving resources, but complex organisms have had less success with this. Of course, bears can den up for the winter in places where their body heat and the insulation of the den materials can make survival possible, especially if there is a good blanket of snow. A dry cold winter spells death for many bears, though. Natual selection can operate on a DAILY basis, not just across years, decades and centuries.

 

[Gold Barz]

So evolutionists are against the idea of increasing complexity over time? what does sA mean by "its not in the cards" if it wasnt it the cards then why did it happen?

"It currently appears there are few, if any just like us 'out there'" - I don't think that we can say this, atleast not yet, because we currently are still in the dark...way in the dark, as if today you could say that there are no aliens, they don't exist at all because we haven't made contact but I doubt that it will stay that way in a hundred or so years.

 

[turbo]

So evolutionists are against the idea of increasing complexity over time? what does sA mean by "its not in the cards" if it wasnt it the cards then why did it happen?

Let's refine the concept a bit. Evolutionists believe that natural selection ("survival of the fittest" in the popular jargon) will determine which life-forms pass on their genetic material and which will fade or die out. Evolutionists accept that complex critters have evolved from simpler ones, but most of them would not be so nutty as to propose that there is a natural law that favors complexity. They will agree however that organization, cooperation, and differentiation of simple organisms has allowed complex life forms to develop, and that the viability of these more complex life forms (like the simpler organisms preceding them) is determined by environmental factors. This is the basis for the concept of Natural Selection.

Please note: This is not a zero-sum game and there is no clear either-or. A life-form that is in decline can quickly become ascendant if climatic conditions favor it for a generation or two. Likewise, a genetic line that has thrived for a number of years (or much, much longer) can be wiped out by a generation or two of adverse conditions, if the adversity is severe enough.

 

[Chronos]

I would be nutty enough to support the proposition that natural selection favors complexity. In my mind, it is the biological extension of the second law of thermodynamics.

 

[SpaceTiger]

I would be nutty enough to support the proposition that natural selection favors complexity.

As would I, though I think we have to define "natural law" in this discussion, because I wouldn't say that evolution is a fundamental law of nature either. I would reserve that title for the fundamental laws of physics and say that things like evolution (and the corresponding tendency to complexity) are just logical extensions of those physical laws. I don't mean this to diminish the biological sciences, just to clarify the terms of the debate.

In my mind, it is the biological extension of the second law of thermodynamics.

How so? I'm not seeing the analogy.

 

[Nereid]

At the risk of going over the same ground we've all been over, several times already, let me go over some of the same ground we've all been over, to see if this thread has anything new

1. To what extent is 'intelligent, complex life' on Earth the result of processes that are rare or unique?[/color]

We have no other example of 'intelligent, complex life' (or indeed, any other life). Without any other datum, in what way is any answer to this question different from speculation?

2. Do we have good theories on the formation of solar systems ("good" = can produce predictions about 'earth-like planets' with confidence)?[/color]

No.

3. Do we have good observations of earth-like planets in other solar systems?[/color]

No.

4. Can we reliably estimate the frequency of E.L.E.s for solar systems other than our own?[/color]

This is important because there is one set of circumstances that the geological record is very clear on concerning the maladaptability of 'intelligence' - E.L.E.s (thank you, Deep Impact). In mass extinctions, species/genera/families/orders/classes with limited ranges don't survive. Within genera/families/orders/classes, for those with wide ranges, the survivors are nearly always small 'generalists', not big 'specialists'. It would be interesting to see if a case could be made that 'small generalists' and 'intelligence' are not mutually incompatible.

IOW, E.L.E. frequency is a critical factor in the evolution of complex life (at least it is here on Earth - see #1 above). If they're too high (how high?), intelligence just can't get going, no matter how many times complex life gets started.

(what triggers E.L.E.s? Well, we know asteroid and comet impact do; we can be pretty sure that nearby supernovae - and more distant GRBs - could; perhaps close encounters of the stellar/giant molecular cloud/rogue planet kind could too? Perhaps having a Local Group galaxy go 'BL Lac' on us might too? Perhaps there are geophysical causes too?)

To answer the question: No.

5. Are the principle of mediocrity and Occam's Razor 'scientific'?[/color]

No.

These are sometimes used by one side or the other in these sorts of discussions - what is their status wrt providing a scientific answer?

6. Do we understand the key aspects of why 'intelligence' seems to be favoured by evolution (other than for E.L.E.s)?[/color]

No.

For example, the Kingdom Plantae is also 'complex life', yet I doubt anyone would even try to make a case that evolution favours the development of 'intelligence' in plants.

I think I'll stop here ... except to add that several posts in this thread also suffer from a poor appreciation of the timescales (for example, if 'intelligence' is so adaptively favourable, how come only one of the higher primates has a wide range? How come Homo sap. (or was it another Homo species?) went through a population bottleneck?)

 

[SpaceTiger]

5. Are the principle of mediocrity and Occam's Razor 'scientific'?[/color]

No.

These are sometimes used by one side or the other in these sorts of discussions - what is their status wrt providing a scientific answer?

I agree on all points but this one. I don't think something needs to provide a definite answer in order to be scientific. I would say that any scientist who doesn't consider Occam's Razor in evaluating competing theories is a very poor one indeed.

Also, another nitpicky thing. From your definition of "good", we don't have any good theories for planet formation, but I'm not sure it's the best definition to be using. Does the fact that we can't predict exactly when and where a storm will occur mean that we don't have good theories of how they form? If something is chaotic or just sensitive to initial conditions, then a good theory will simply acknowledge its limited predictive power. I strongly suspect that, given what we know about protoplanetary disks, planet formation may indeed be chaotic.

 

[Nereid]

I agree on all points but this one. I don't think something needs to provide a definite answer in order to be scientific. I would say that any scientist who doesn't consider Occam's Razor in evaluating competing theories is a very poor one indeed.

I agree that a strong case for Occam's Razor being part of science (which is, in a nutshell, what scientists *do*) could be made. A further discussion of this would be OT (a topic for HPS, perhaps?), except in one respect: when it comes to humans applying the razor to discussions concerning intelligent, earth-like life, great care must be exercised, to even identify when what seems like an application of the razor is, in fact, narcism or hubris. (somewhat analogous to conflating 'complex life' with Animalia or Mammalia, or picking 'intelligence' out of a million Animalia characteristics as the sole 'trend' to consider).

Also, another nitpicky thing. From your definition of "good", we don't have any good theories for planet formation, but I'm not sure it's the best definition to be using. Does the fact that we can't predict exactly when and where a storm will occur mean that we don't have good theories of how they form? If something is chaotic or just sensitive to initial conditions, then a good theory will simply acknowledge its limited predictive power. I strongly suspect that, given what we know about protoplanetary disks, planet formation may indeed be chaotic.

We're on the same page here (put it down to trying to get it 'right' in but a sentence or two).

So far as this discussion is concerned, a 'good' theory of planetary formation would be one which could predict - with confidence - the liklihood of 'earth-like planets' forming, in a statistical sense (not a deterministic one). IOW, something like "out of 1 million collapsing gas clouds of mass {X} and composition {Y} (and other parameters), at least one 'earth-like planet' will form in 10,000 of them, +/- 30%" (of course, 'earth-like planet' would need to be defined too - mass+composition+rotation rate+timeframe? +range of orbital parameters?? +a 'Moon'?)

 

[SpaceTiger]

when it comes to humans applying the razor to discussions concerning intelligent, earth-like life, great care must be exercised, to even identify when what seems like an application of the razor is, in fact, narcism or hubris.

Unfortunately, the logic we would use to determine whether or not intelligence is common would have to depend on a model of universe creation, which of course doesn't exist. There are many possibilities:

1) Intelligent Design (the kind consistent with science) - No kind of statistical inference could be made about intelligent life. We have to just look and see.
2) One Universe with random laws - Intelligence likely exists elsewhere, by the Copernican principle.
3) Many universes with random laws - We would only see ourselves in a universe in which we could exist. To infer the likelihood of extraterrestrial intelligence, we would have to integrate under the space of possible physics times the density of intelligent civilizations within them to determine the likelihood of us being in a "multi-intelligence" universe. I won't try to guess at what the result would be.
4) Many universes evolving towards intelligence (perhaps it sustains their existence) - Intelligence likely exists elsewhere, since the universe would likely be specifically tailored to giving rise to intelligence.
5) Many universes evolving towards black hole creation - Not sure. Universes that create many black holes would likely also be long-lived universes, but it's not obvious that it would favor the formation of life in any other way.

So far as this discussion is concerned, a 'good' theory of planetary formation would be one which could predict - with confidence - the liklihood of 'earth-like planets' forming, in a statistical sense

My guess is that our first constraint on this will come from the data rather from a rigorous theory. We already have evidence for planets with Earth-order masses around pulsars and perhaps some detections from microlensing. Also, the fact that our solar system formed several planets around an Earth mass is, I think, support for their prevalence.

 

[Nereid]

Unfortunately, the logic we would use to determine whether or not intelligence is common would have to depend on a model of universe creation, which of course doesn't exist. There are many possibilities:
1) Intelligent Design (the kind consistent with science) - No kind of statistical inference could be made about intelligent life. We have to just look and see.
2) One Universe with random laws - Intelligence likely exists elsewhere, by the Copernican principle.
3) Many universes with random laws - We would only see ourselves in a universe in which we could exist. To infer the likelihood of extraterrestrial intelligence, we would have to integrate under the space of possible physics times the density of intelligent civilizations within them to determine the likelihood of us being in a "multi-intelligence" universe. I won't try to guess at what the result would be.
4) Many universes evolving towards intelligence (perhaps it sustains their existence) - Intelligence likely exists elsewhere, since the universe would likely be specifically tailored to giving rise to intelligence.
5) Many universes evolving towards black hole creation - Not sure. Universes that create many black holes would likely also be long-lived universes, but it's not obvious that it would favor the formation of life in any other way.

Shades of the anthropic principle!

And the logic would have to incorporate a great deal more than models of creation!

Here's something that can be fun: MWI (search on MWI in PF ... hundreds of pages and dozens of threads!).

My guess is that our first constraint on this [prevalence of 'earth-like planets' among 'solar' systems] will come from the data rather from a rigorous theory. We already have evidence for planets with Earth-order masses around pulsars and perhaps some detections from microlensing. Also, the fact that our solar system formed several planets around an Earth mass is, I think, support for their prevalence.

I agree; what I was pointing out is that we don't have any significant constraints/guidelines/bases for making estimates ... either theoretical or observational (beyond our own solar system)!

 

[SpaceTiger]

And the logic would have to incorporate a great deal more than models of creation!

Such as? I think reasonable knowledge of the generative model (in this case, the particulars of universe formation) would be enough to do inference. The basic assumption going into the above is that, of all intelligent civilizations in all universes, we have an equal probability of asking this question from the point of view of anyone of them.

 

[Gold Barz]

I think the shortest way to explain evolution is that over time evolution diversifies life...agree?

 

[Nereid]

And the logic would have to incorporate a great deal more than models of creation!

Such as? I think reasonable knowledge of the generative model (in this case, the particulars of universe formation) would be enough to do inference. The basic assumption going into the above is that, of all intelligent civilizations in all universes, we have an equal probability of asking this question from the point of view of anyone of them.

How about models for/of:
- 'intelligence'?
- estimating the 'characteristic time' of 'intelligence'?
- estimating the 'lead time' for 'intelligence' (assuming the universe model(s) are not 'steady state')?
- estimating the 'lifetime' of 'intelligence' (not - necessarily - the same as 'characteristic time'; model-dependent?)?

re 'intelligence', we would need to have a handle on the extent to which it is 'binary' ('intelligence' is either present or not) or not; if 'continuous', or 'can occur in a range of discrete states', then a handle on how all the above would vary, by 'state of intelligence' (or whatever), ...

 

[Entropy]

I think the shortest way to explain evolution is that over time evolution diversifies life...agree?

No. Evolution doesn't inherently cause diversity. Over most of Earth's history life stayed relatively unchanged and did not try to diversify. Evolution only states that if it is favorable for life to diversify or change it will try to do so.

 

[Nereid]

I think the shortest way to explain evolution is that over time evolution diversifies life...agree?

A nice idea ... do the data support it? And if they do support it, in spades, here on Earth, what basis do you have for supposing it operates to the same effect elsewhere?

Some considerations for Earth: to what extent does the 'diversification' depend upon the (multi-dimensional) ranges of environments capable of being occupied by living things? An example: if all the world were deep ocean, what would the time derivative of 'diversity of life' look like? If all the world were ('forever') isolated islands ('islands in the sky' are islands)? If a power-law of islands, subject to a power-law of changes? If our quantum of time were a billion years?

 

[Gold Barz]

" Evolution only states that if it is favorable for life to diversify or change it will try to do so."

Oops, sorry I meant to say this...that it would change if the change was in favor.

 

[SpaceTiger]

re 'intelligence', we would need to have a handle on the extent to which it is 'binary' ('intelligence' is either present or not) or not; if 'continuous', or 'can occur in a range of discrete states', then a handle on how all the above would vary, by 'state of intelligence' (or whatever), ...

The idea was that these models of intelligence would have to be derived from the parameters (i.e. physical laws) of the universe in question, as I specified in item #3. There would not need to be more information, just more work. In some cases, however, I think inference can be done without detailed models (that is, we can use our intuition). In point 1, for example, the answer is very easy -- there's no way for us to infer the probability of extraterrestrial intelligence because the model invokes something not governed by chance. In #2, I think we can just invoke Occam's Razor, since no anthropic selection biases are present. In #3, we would have to derive the things you're describing in detail. #4 is even more biased towards multiple intelligence than #2, so the inference is obvious. Finally, #5 would probably have to be worked out in detail as well.

I'm not suggesting we can get definitive answers, just that we can develop an intuition for what would be probable if we had a generative model with which to work. The issue of priors can be debated -- Do we choose a random species? A random point in time of intelligent life? A random organism? It's not clear. I would still contend, however, that none of the conclusions I've drawn so far are dependent upon that choice.

 

[turbo]

No. Evolution doesn't inherently cause diversity. Over most of Earth's history life stayed relatively unchanged and did not try to diversify. Evolution only states that if it is favorable for life to diversify or change it will try to do so.

We've got to be careful with this. Evolution is not a law or principle that causes change.

1) Live things sometimes change.
2) Sometimes they can pass the change on to successive generations.
3) Sometimes the changes are favorable to the survival of the organism - most probably are either neutral or negative.
4) If the change has survival value for the individual (or aids in the success of reproduction) and can be passed on, the change will express itself in successive generations (presuming the trait is not recessive or poorly-expressed in successive generations).
5) This is Natural Selection.

Evolution does not MAKE organisms change or try to change-it does not exert a force on organisms. Evolution is the observed progression of the development of species and sub-species, and their differentiation. It is entirely driven by Natural Selection. In other words, if the variations in individual creatures are both beneficial to the survival and/or reproductive success of the creature AND can be passed on successfully to successive generations, the improvements in those creatures will become engrained in the species.

As in the study of beak shapes in Darwin's finches, it should be noted that the little variations in individuals can be positive or negative on very short time-scales, due to environmental variations. For instance, dry year, harder drier seeds = positive selection for birds with the types of beaks that can most efficiently gather and process them into usable food.

 

[Chronos]

No. Evolution doesn't inherently cause diversity. Over most of Earth's history life stayed relatively unchanged and did not try to diversify. Evolution only states that if it is favorable for life to diversify or change it will try to do so.

Sometimes semantics create the illusion of disagreement where none of any substance exists. Evolution is a chaotic process. Mutation, which is the physical mechanism behind evolution, is an utterly random event. It happens constantly and evironmental factors, like exposure to radiation or mutagenic material, accelerate it. There is only a microscopic chance that any given mutation will both be advantaqeous and survive long enough to be passed on. Life initially diversified with relatively great speed because there were so many available unfilled niches. Almost any mutatation had a fighting chance at a grub stake. Hence, unfilled niches favor biodiversity. Once, however, all niches are filled, the game changes. Current residents, often by dent of sheer numbers, have the advantage. You must be one lucky mutant to invade their turf. This is where evolution favors specialization [complexity]. A specialist can conquer an existing niche merely by doing one thing better than everyone else. Of course, when the specialist is successful, it has a spillover effect on other niches, making formerly 'perfectly' adapted organisms vulnerable to conquest [hence once again fueling diversity].

The diversity and complexity of life today is merely a group photograph of the latest batch of lottery winners. All we can say with any confidence, given current evidence, is that few of them will be around to boast of their 'success' in another 100 million years.

 

[Nereid]

Sometimes semantics create the illusion of disagreement where none of any substance exists.

Thank you Chronos!

Doing a little cut&pasting, to get all the key things in one place ...

Unfortunately, the logic we would use to determine whether or not intelligence is common would have to depend on a model of universe creation, which of course doesn't exist. There are many possibilities:
1) Intelligent Design (the kind consistent with science) - No kind of statistical inference could be made about intelligent life. We have to just look and see.
2) One Universe with random laws - Intelligence likely exists elsewhere, by the Copernican principle.
3) Many universes with random laws - We would only see ourselves in a universe in which we could exist. To infer the likelihood of extraterrestrial intelligence, we would have to integrate under the space of possible physics times the density of intelligent civilizations within them to determine the likelihood of us being in a "multi-intelligence" universe. I won't try to guess at what the result would be.
4) Many universes evolving towards intelligence (perhaps it sustains their existence) - Intelligence likely exists elsewhere, since the universe would likely be specifically tailored to giving rise to intelligence.
5) Many universes evolving towards black hole creation - Not sure. Universes that create many black holes would likely also be long-lived universes, but it's not obvious that it would favor the formation of life in any other way.

And the logic would have to incorporate a great deal more than models of creation!

Such as? I think reasonable knowledge of the generative model (in this case, the particulars of universe formation) would be enough to do inference. The basic assumption going into the above is that, of all intelligent civilizations in all universes, we have an equal probability of asking this question from the point of view of anyone of them.

How about models for/of:
- 'intelligence'?
- estimating the 'characteristic time' of 'intelligence'?
- estimating the 'lead time' for 'intelligence' (assuming the universe model(s) are not 'steady state')?
- estimating the 'lifetime' of 'intelligence' (not - necessarily - the same as 'characteristic time'; model-dependent?)?

re 'intelligence', we would need to have a handle on the extent to which it is 'binary' ('intelligence' is either present or not) or not; if 'continuous', or 'can occur in a range of discrete states', then a handle on how all the above would vary, by 'state of intelligence' (or whatever), ...

The idea was that these models of intelligence would have to be derived from the parameters (i.e. physical laws) of the universe in question, as I specified in item #3. There would not need to be more information, just more work. In some cases, however, I think inference can be done without detailed models (that is, we can use our intuition). In point 1, for example, the answer is very easy -- there's no way for us to infer the probability of extraterrestrial intelligence because the model invokes something not governed by chance. In #2, I think we can just invoke Occam's Razor, since no anthropic selection biases are present. In #3, we would have to derive the things you're describing in detail. #4 is even more biased towards multiple intelligence than #2, so the inference is obvious. Finally, #5 would probably have to be worked out in detail as well.

I'm not suggesting we can get definitive answers, just that we can develop an intuition for what would be probable if we had a generative model with which to work. The issue of priors can be debated -- Do we choose a random species? A random point in time of intelligent life? A random organism? It's not clear. I would still contend, however, that none of the conclusions I've drawn so far are dependent upon that choice.

ST and I may be 'talking past each other' ... try substituting 'asteroids' for 'intelligence' in the above - does it make any difference? How about 'a&W3'? or 'John Bahcall'?

Also, there seems to have been a slight shift at one point "intelligence" -> "intelligent civilizations" -> "intelligence"

 

[SpaceTiger]

Doing a little cut&pasting, to get all the key things in one place ...ST and I may be 'talking past each other' ... try substituting 'asteroids' for 'intelligence' in the above - does it make any difference? How about 'a&W3'? or 'John Bahcall'?

Perhaps I'm misunderstanding you again, but I don't think you could have exactly the same discussion on asteroids because there's no issue of anthropic selection bias. I don't know what a&W3 is and I'm not sure any of this would make sense when talking about an individual person, assuming they actually were individual.

If you're suggesting that we don't actually disagree, I think you're probably right, I was just trying to clarify my previous posts. The things you suggested above probably will matter, but I was assuming they were derivable from the universe generation model. Are we on the same page now?

Also, there seems to have been a slight shift at one point "intelligence" -> "intelligent civilizations" -> "intelligence"

I was being sloppy and using them interchangably because it didn't matter for the conclusions I was drawing. I think to really nail down the anthropic selection bias, you have to ask, "What are the conditions required for a being to ask this question?" Would this include a requirement for civilization? Perhaps, perhaps not.

 

[turbo]

I was being sloppy and using them interchangably because it didn't matter for the conclusions I was drawing. I think to really nail down the anthropic selection bias, you have to ask, "What are the conditions required for a being to ask this question?" Would this include a requirement for civilization? Perhaps, perhaps not.

Hi, ST! In the case of humans, what we commonly call "civilizations" nowadays arose from the trend toward agrarian societies, which allowed humans more control over their destinies. They could store seed, plant crops, force the land to provide more and more food per acre, etc and break away from the hunter-gatherer paradigm. This also allowed humans to accumulate material things, since their possessions did not have to be hauled all over the place whilst tracking down herds of animals to hunt, finding ripe fruit to eat, gathering wild grains, etc. They raised animals and plants for food right where they lived. It is no wonder that powerful, long-lived civilizations grew where water, nutrients, etc were plentiful (along the Nile, the Tigris, the Euphrates, the shores of the Mediterranean, etc).

I'm being long-winded, but the term "civilizations" could also extend to small tribal bands that hunted, gathered, and lived communally. The difference is that these folks left fewer clear traces, and we know less about them. Once the Babylonians and the Egyptians started writing things in clay and stone (even mundane stuff, like how many measures of wheat a farmer had brought to the storage building and how much he was entitled to retrieve) they made it possible for us to learn a lot about them. The early native americans, in contrast, who cooperatively hunted bison (and even mammoths, earlier) did not leave much in the way of records, but their civilizations were probably very rich and complex, and I wish we could know them better.

We can make an extension to whales and the great apes that travel in bands, form strong bonds, and observe social heirarchies. At what level of species intelligence and at what level of social complexity do we declare that these creatures have established a "civilization"? We'll have better luck nailing Jello to a wall than answering that one, I fear.

 

[SpaceTiger]

At what level of species intelligence and at what level of social complexity do we declare that these creatures have established a "civilization"? We'll have better luck nailing Jello to a wall than answering that one, I fear.

"Civilization" is a vague term. Fortunately, for the issue at hand, that question isn't relevant -- I only said "intelligent civilization" in one post as a substitute for "intelligence". As I already said, what we have to determine is the point at which the ETs could ask what we are asking (i.e. is there anyone else out there?). Not to say that this is an easy question either, but it certainly sidesteps the ambiguities you're referring to. Clearly, there is no other creature on Earth capable of having the discussion we're having. Keep in mind that I'm trying to establish a circumstance in which we could use reason to develop an intuition for this question, not try to answer it myself.

Such an intuition might be impossible to develop, but there are things that may simplify the logic. On earth, intelligence seems to be a runaway process. That is, the complexity of our brains seems to be far beyond that of any other earthly animal. This implies that the continuum of intelligence may, in fact, be multimodal. In other words, it may be that there are very few creatures with intelligence between us and, say, dolphins, but plenty on either end. If this is the case, then the question becomes binary; that is, is the creature intelligent or not? The ambiguities of a continuum could be ignored. Furthermore, civilization seems to have developed very quickly, indicating that any intelligent creature would become sophisticated enough to question the universe on a very short timescale, leaving the "lifetime" issue negligible as well. If both of these things are a general rule, then establishing our priors simply becomes a matter of "counting" intelligent creatures.

 

[turbo]

I only said "intelligent civilization" in one post as a substitute for "intelligence". As I already said, what we have to determine is the point at which the ETs could ask what we are asking (i.e. is there anyone else out there?). Not to say that this is an easy question either, but it certainly sidesteps the ambiguities you're referring to. Clearly, there is no other creature on Earth capable of having the discussion we're having.

I think your inclusion of the term "civilization" is key, though. An individual organism may be very intelligent, but without the prior support and and the passing on of knowledge throughout generations, it may be impossible for any reasonably intelligent being to even pose the question.

It seems inconceivable that you or I (without access to the scientific, mathematical, and philosophical knowledge of the centuries prior to us) could look at the night sky and say "those are stars and they are each just like our sun, but that big glow over there (M31) is another group of stars like this one, and there is a great possibility that there are other planets around lots of those other stars". We stand on the shoulders not only of giants, but of countless generations of deeply committed seekers of truth. Sometimes they were right, sometimes wrong, but the key fact is that our "civilization" made it possible for us to save, transmit, and re-interpret their insights. This could not have happened without the continuity and stability provided by our "civilization". The collective wisdom of a society is essential to the abilities of its members.

 

[SpaceTiger]

I think your inclusion of the term "civilization" is key, though. An individual organism may be very intelligent, but without the prior support and and the passing on of knowledge throughout generations, it may be impossible for any reasonably intelligent being to even pose the question.

Yes, I am on the same page with you there, but I'm saying that what doesn't matter is our definition of the term "civilization", because it's just a means to an end, which is answering the question I'm posing. Many of the complications you brought up in your other post (concerning history and biology) are mostly ambiguities that arise when you're trying to come to a common consensus on what you're going to call a civilization. I agree that they're important for that purpose.

However, we know without a doubt that, for our purposes, the result was very simple. Humans evolved to ask the question (with the help of a civilization), but no other earthly creature did. What I'm getting at in the second paragraph of my last post is twofold:

1) This result may have been inevitable (that is, all intelligent creatures may develop to ask this question in a very short time).
2) Intelligence may be very easily defined (if the distribution is really multimodal) and we could immediately rule out creatures like whales and great apes without getting into the details of our definition of "civilization".

I admit that I don't have enough data to say these things with certainty, but there are good reasons (some of which I gave in my last post) for thinking they're true.

 

[turbo]

http://news.yahoo.com/s/ap/20050902/ap_on_sc/clever_whale

I thought that this might be an interesting addition.

 

[Nereid]

http://news.yahoo.com/s/ap/20050902/ap_on_sc/clever_whale

I thought that this might be an interesting addition.

If I'm not mistaken, this kind of behaviour - broadly - has been observed in several species of mammal (chimps, dolphins, gorillas?), and also of avian (rooks?).

That several other species have the capability to build 'mental models' of the world has now been demonstrated quite solidly, ditto that they can engage in 'conscious' deception, 'conscious' (i.e. out of 'choice', not 'necessity') cooperation, etc.

The main thing 'lacking' - from our {insert favourite adjective here} perspective - is a means of communication as rich as our spoken language (the written part is a mere detail).

As to whether an 'intelligent civilization' (I agree with ST that, for our purposes here, re Homo sap., the details matter little) has some inevitability (i.e. the 'rules of the universe' lead inexorably to the instantiation of an intelligent civilization, some individuals within such then turn around and ask the question in reverse)?

BTW, SpaceTiger clarified my 'asteroids', 'John Bahcall' etc exercise ... it's not a free parameter, whatever you insert into the slot in the sentence (logic proposition?), it has a bounded meaning, something akin to 'is able to ask the anthropic question about the universe'.

Of course, I would argue that isn't science, if only because (so far) there is but one data point.