What is the logic of assuming the existence (or nonexistence) of alien life

[Paul Wally]

When I last checked, 'logical possibilities' (meaning pure speculations) are vastly different from proper theories the latter of which, I agree, should ultimately lead to useful real-world data.

Obviously what I'm referring to, are those logical possibilities consistent with established scientific theory. Say for instance that if models derived from established scientific theories of physics and chemistry predict a high exo-life likelihood would you then consider such a prediction to be "pure speculation" too? I wouldn't call it speculation if it just follows logically from such a premise, i.e.,if the conclusion follows logically from the premise then it's truth value is conditional on the truth value of the premise.

Which established scientific theory leads to the emergence of universal life ?

I didn't say that. What I'm saying is that if we take established scientific theories as our premise, then the question is: "What follows from established scientific theory?".
I explicitly phrased it as a question. How is it possible that you could have overlooked that?

It doesn't ! Did I say it had to ?Specifically, which laws of nature, and which currently established scientific theories are you formulating your premise on ... and why ?

This is what you said:

(Similarly, the lack of data cannot in itself, be considered as a valid basis for formulation of the premise that exo-life doesn't exist either, as this leads to the logical fallacy of 'argumentum ad ignorantium').

My point is, why would anyone attempt to formulate exo-life existence/ non-existence as a premise? Doesn't it make more sense to look at it as a possible conclusion of some premise?

On your question of "which laws of nature" I'm formulating my premise. Exactly which laws, is not really relevant in terms of my argument. Let's just call it X. Let's call "exo-life" L. The question would then be: Does X--> L? So I'm not formulating a premise. I'm explaining on a general level what the relation between premise and conclusion is, as far as it relates to the problem of life emergence.

Possible conclusions are:
1) Life is an unlikely occurrence.
2) Life is a likely occurence.
3) The question of the emergence of life is undecidable on the premise.

Note that undecidability is something that will have to be proven mathematically, perhaps a Godel-type undecidability, but this hasn't been proven to my knowledge. You keep mentioning that some assume "classical physics", but say we take classical physics as our premise; has any of the above-mentioned conclusions been proven to follow from classical physics? If not, then we cannot say that the assumption of classical physics leads to the conclusion (2): "Life is a likely occurrence". Classical physics does however predict the existence of chaos, so your view that there is some fundamental incompatibility between classical physics and chaos is pure myth, but it's a myth that you strongly believe in because it holds your arguments together.

But that's just my point ! The usage of purely classical physics theory, to justify either (1) or (2), is inappropriate.

On what basis are (1) and (2) "inappropriate"? All three are equally valid conjectures in the context of classical physics. To my knowledge, none of those three has been proven logically, and this doesn't imply that it cannot be logically proven. Only if (3) is proven can we say that the likelihood of exo-life is undecidable in classical physics.

I would've said that mathematics exposed the existence of chaotic behaviours in theory. Measured data then confirmed its existence in nature. The expected determinism inherent in theoretical mathematics however, doesn't nessarily map across into the real world .. and that is one of the big lessons from Chaos Theory. Huh ?? Please explain further the concepts you are trying to express on my behalf !??!
I do not recognise them from your paraphrasing !

Physical theory is mathematical at its core. You cannot separate mathematics from theory as you're doing, and what is "theoretical" mathematics supposed to refer to? Mathematics is theoretical. And how can mathematics be deterministic/ non-deterministic? If chaos theory is mathematical at it's core, how can it tell us how mathematics maps to the real world? How do we conceptualise this mapping transformation without mathematics? I suspect that this "big lesson" you've apparently learned from chaos theory is one big misconception.

[Van Rijn]

Well, you've qualified the hypothetical scenario under the assumption of 'strong evidence'. Strong evidence would be prior biological test results, sourced from some local planet other than Earth, (after all, we are talking about biology as the subject, aren't we ?), or perhaps evidence sourced from some kind of lab synthesised, second abiogenesis, or the reception of an intelligible SETI signal(s), ET(s) poking faces into a remotely monitored robotic camera, etc, etc.

No. There is life on Earth. If you find evidence for things that would be reasonably explained by earthlike biology on earthlike worlds, but not reasonably explained by non-biological processes on an earthlike world, then you have strong evidence for life.

The existence of life on Earth, does not imply life exists elsewhere, is a present-day fact. It needs to be countered with falsifying new evidence of equal 'weight'.

What exactly is to be falsified? Let's apply this argument to exoplanets, going back a few years. Would you consider this a reasonable argument?

The existence of planets in the solar system does not imply planets exist elsewhere, is a present-day fact. It needs to be countered with falsifying new evidence of equal 'weight'.

I've earlier pointed out my disagreement with your implication claim. Now, it sounds like you're trying to argue for an assumption that life is unlikely, as opposed to an assumption of "we don't know yet." The existence of life would have to be established through reasonable evidence, but there is no non-life argument to falsify.

And, sorry, but life on Earth does have implications for life elsewhere. It doesn't guarantee that life exists elsewhere, but chemistry on Earth has implications for chemistry elsewhere, physics on Earth has implications for physics elsewhere, and so does Earth life (being based, after all, on chemistry and physics).

In the case of a firm conclusion of exo-life, I think there's a clear need for way more justification, over and above what is needed to support the claim of the discovery of 'Earth-like worlds'.

How Earth-like does it need to be? Sure, it isn't enough to say you have a planet that's roughly Earth's mass, but if you have multiple lines of evidence that would fit the results of Earth biology, but would not, taken together, be reasonably explainable by non-biological processes, would you say that was insufficient?

[caveman1917]

We know that there is a non-zero chance of life arising in a random system with our physical laws because we know it has happened at least once.

That's incorrect, you cannot deduce prior probabilities that way. Suppose we have a game where you think of a natural number and i have to guess it. Suppose i get it right. Then we know the event "me getting it right" has happened at least once, but that doesn't mean there is a non-zero chance of that happening, the chance is identically zero.

But even if we did assume there is a non-zero chance of a random system having life then the distribution of life bearing systems could be approximated as a poisson distribution. This means there will be a chance that there is exactly one planet with life, and that chance can be made arbitrarily high by having an arbitrarily low chance per-system. Since you have no way to deduce that per-system chance, nor even deduce that it isn't zero, this probabilistic argument falls apart.

[caveman1917]

Secondly, if you are assuming the parent population of the distribution of life in the obs. universe to be a normal one, there is no evidence of that.

Actually there is, it's called the central limit theorem. Given the combination of a sufficient number of independent identically distributed stochastic variables, the resulting distribution will approach a normal distribution. Because of the vast interstellar (and if not, intergalactic) distances, the chance of life appearing in one system is independent of it appearing in another. Since the same physical laws hold everywhere, the base distributions would be identical, and adding in the huge number of such independent systems the central limit theorem holds.

[caveman1917]

Have a read through this thread (from my post #89 onwards). Caveman1917 explains the basis of validity (from a mathematical principals perspective).

Not that i want to sidetrack this discussion as i may have done with the one being linked to, but i find it somewhat odd that you quote an explanation of mine as support for an incorrect application of it.

Let P equal "we know of only one" (what you say) and let Q equal "we know of at least one" (what primummobile said).

Then is true, and because that last statement is also true.

If you say that you are right and he is wrong then you state which is the negation of (as ) and is thus false.

It is hypothetically possible that he is right and you are wrong (if we would know of some greater number than one), but not the other way around.

[Selfsim]

Folks;

Due to the overwhelming number of responses requested by so many posters in this thread, I’m finding it extremely difficult to continue my part of this discussion given the amount of time I presently have available for responding. I also do not wish to appear to exhibit a greater than tolerable level of ‘tenacious’ behaviour, which would be required from this point onwards, (particularly with regard to a hypothetically-oriented exo-life discussion). I also have no desire to personally offend.

My position has been, and will continue to be, simply that the present state of knowledge on the question of the existence of exo-life, draws the generalised conclusion of ‘Unknown’. For me, this is a valid state, is clearly distinguishable from the speculative ‘exo-life exists’, or the equally speculative ‘exo-life does not exist’, and still allows for further exploration.

I find that many folk somehow relate this position to my attempting to rule out the speculative possibility that exo-life exists, which is not the point I’m making. Similarly, I am not attempting to rule out the speculative possibility for the non-existence of it, either. Thorough exploration of both of these views I find, results in a balanced view.

The key general point I'd like to make, is that present knowledge and speculation of any kind are distinguishable entities in science, and should be maintained that way, (in mind, and in conversation).

I’ve come to the conclusion that this medium for communications, when it comes to explaining this perspective is inadequate, as there is too much background and detail to cover. Frankly I’m surprised that so much is required, in order to explain an ‘Unknown’ state, coming from present knowledge.

As I presently have a choice of diplomatically, and respectfully, withdrawing from this discussion, for the benefit of preserving harmony by avoiding miscommunications within the community, and out of respect for those I have engaged with in this thread, I choose to exercise this option.

Kind regards

[primummobile]

That's incorrect, you cannot deduce prior probabilities that way. Suppose we have a game where you think of a natural number and i have to guess it. Suppose i get it right. Then we know the event "me getting it right" has happened at least once, but that doesn't mean there is a non-zero chance of that happening, the chance is identically zero.

But even if we did assume there is a non-zero chance of a random system having life then the distribution of life bearing systems could be approximated as a poisson distribution. This means there will be a chance that there is exactly one planet with life, and that chance can be made arbitrarily high by having an arbitrarily low chance per-system. Since you have no way to deduce that per-system chance, nor even deduce that it isn't zero, this probabilistic argument falls apart.

I'm a little confused by what you mean, but I'd appreciate it if you could provide a critique about what I'm about to say...

In the game you reference, you are referring to natural numbers, which is an infinite set. If we changed it and said that I am thinking of a natural number between 1 and 10, inclusive, you would have a .1 probability of guessing it correctly on the first try if both my choice and your guess were truly random. In the next round, your chances of correctly guessing would be also .1, but the probability you would guess correctly twice in a row is .01, three times in a row .001, and so on. But you know that. I'm not seeing how you are equating the probability of guessing a number in an infinite set to a finite set.

As to my statement, I don't believe that there was an infinite set of possible quantum states to begin the universe, nor do I believe that there is an infinite set now. If I had a handful of dice and dropped them on the floor, there would be a finite number of ways they could land. It does not matter to my argument how many dice I have or what style they are. Any combination that could happen has a probability of happening. Now there are combinations, such as a six-sided die coming up a seven, that could not happen. But, if we were to see even one instance of a six-sided die coming up a seven, we would have to assume that the probability of that happening is not zero.

If you extend that to the universe, and an outside observer were to note that the formation of Earth and the development of life was impossible according to the physical laws of the universe, that observer would have to conclude that the probability of it happening is zero. But if he were to observe even one instance of that zero probability event occuring, he would have no choice but to conclude that the probability was, in fact, non-zero.

I guess it would help if you were to use examples from a finite set of possibilities to explain your thinking, if you would be so kind. Or just explain to me why it wouldn't matter if you had a finite set of possible outcomes versus an infinite set, if that is the case.

Thanks.

[Paul Wally]

The process in between not knowing and knowing is what scientific research is all about. Now, there's not one correct process to follow, because it's a matter of heuristics. One way is to look at what we currently know and then to see what can be deduced from that. Does physics and chemistry, as we currently understand it, imply that life must be a common phenomenon? That is still an open question. To say that all we can conclude from our current state of knowledge is that the existence of exo-life is unknown, is like being presented with a mathematical problem and then coming to the conclusion that the solution is unknown!

[primummobile]

Folks;

Due to the overwhelming number of responses requested by so many posters in this thread, I’m finding it extremely difficult to continue my part of this discussion given the amount of time I presently have available for responding. I also do not wish to appear to exhibit a greater than tolerable level of ‘tenacious’ behaviour, which would be required from this point onwards, (particularly with regard to a hypothetically-oriented exo-life discussion). I also have no desire to personally offend.

My position has been, and will continue to be, simply that the present state of knowledge on the question of the existence of exo-life, draws the generalised conclusion of ‘Unknown’. For me, this is a valid state, is clearly distinguishable from the speculative ‘exo-life exists’, or the equally speculative ‘exo-life does not exist’, and still allows for further exploration.

I find that many folk somehow relate this position to my attempting to rule out the speculative possibility that exo-life exists, which is not the point I’m making. Similarly, I am not attempting to rule out the speculative possibility for the non-existence of it, either. Thorough exploration of both of these views I find, results in a balanced view.

The key general point I'd like to make, is that present knowledge and speculation of any kind are distinguishable entities in science, and should be maintained that way, (in mind, and in conversation).

I’ve come to the conclusion that this medium for communications, when it comes to explaining this perspective is inadequate, as there is too much background and detail to cover. Frankly I’m surprised that so much is required, in order to explain an ‘Unknown’ state, coming from present knowledge.


Kind regards

I get what you are saying, and I respect that. I just want to point out, in the hopes that you read this, that I don't disagree with you in principle. I just think it is interesting to speculate about what could be, all the while knowing that speculation is distinct from knowledge. For lack of a better way to put it, my gut tells me that there is probably other intelligent life out there. But it also tells me that other intelligent life is probably either exceedingly rare or short lived. When I present an "argument for" that belief, it would be more rightly interpreted as an "argument for why it is not impossible."

You don't know me, but I like to discuss possibilities. Astrophysicists theorize about quark stars, and have even worked out formulae for how a quark star would form and what we would expect to see. But we have never observed a quark star. When I was in junior high, I was taught that black holes were merely mathematical curiousities of GR. That information I was being taught may have been dated, but it still, at one time, represented the mainstream view. We have enough information, from the earth and universe around us, to make guesses as to how things could develop. They may be unlikely and they may not be very rigorous. But it's still interesting to speculate about.

[caveman1917]

If we changed it and said that I am thinking of a natural number between 1 and 10, inclusive, you would have a .1 probability of guessing it correctly on the first try if both my choice and your guess were truly random. In the next round, your chances of correctly guessing would be also .1, but the probability you would guess correctly twice in a row is .01, three times in a row .001, and so on.

True, but we don't know the prior distribution of life-bearing systems. And the evidence we have (life on earth) is perfectly correlated with our existence and therefor useless.

Let's try an example with a dice. Suppose that you want to find the prior distribution over the result of throwing it (ie how fair the dice is) and in order to do that you throw the coin. However suppose that the probability of say 4 given that you throw it is 1. You throw the dice and it lands 4, that didn't give you any information about the distribution. Likewise the probability that there is at least one planet with life given that we are conducting the survey is 1, so that data point does not give any information as to the actual distribution of life-bearing planets. So while it's true that for a finite set the probability is not zero, it can still be arbitrarily small, we didn't constrain it. For that we need evidence that is not correlated with our existence. And a bigger sample.

[primummobile]

True, but we don't know the prior distribution of life-bearing systems. And the evidence we have (life on earth) is perfectly correlated with our existence and therefor useless.

Let's try an example with a dice. Suppose that you want to find the prior distribution over the result of throwing it (ie how fair the dice is) and in order to do that you throw the coin. However suppose that the probability of say 4 given that you throw it is 1. You throw the dice and it lands 4, that didn't give you any information about the distribution. Likewise the probability that there is at least one planet with life given that we are conducting the survey is 1, so that data point does not give any information as to the actual distribution of life-bearing planets. So while it's true that for a finite set the probability is not zero, it can still be arbitrarily small, we didn't constrain it. For that we need evidence that is not correlated with our existence. And a bigger sample.

Ok, I really don't have an argument with that. My point was more along the lines that, because of our existence, we know that our physical laws don't preclude the possibility of life existing.

[Paul Wally]

Ok, I really don't have an argument with that. My point was more along the lines that, because of our existence, we know that our physical laws don't preclude the possibility of life existing.

Yes, we know that our physical laws (if they are a true reflection of reality) do not preclude the possibility of life. My preferred approach, however, is not to attempt a statistical inference from the fact that there's life on Earth but rather, to look at the physical laws and how they make life possible. It is this how-question that I find more interesting than the question of whether or not other life exists. Initially, I think that some kind of simple model must be constructed based on these physical laws or perhaps much simpler laws. Then, "life" must be defined, beginning with a simple definition e.g. life is any structure that can self-replicate and evolve. The model must then be adjusted until "life", as defined emerges. But, the life-outcome must emerge implicitly, and not be explicitly coded within the model. Once such a simple model is discovered, it can be studied further mathematically so that a more general abstract theory can be developed and further refined through application to empirical reality.

You're probably familiar with the field of artificial life, where life-like phenomena in the form of computer simulations are studied. What I would like to see in such studies is an example of artificial abiogenesis, where self-replicating and evolvable artificial organisms emerge from a system wherein no artificial organisms existed prior to emergence. Such a model, even if just a toy-model, should give some valuable insights into the general nature of abiogenesis.

[Colin Robinson]

True, but we don't know the prior distribution of life-bearing systems. And the evidence we have (life on earth) is perfectly correlated with our existence and therefor useless.

I'd agree that we can't conclude very much from the fact that the planet we live on has life. That much, I grant you, is perfectly correlated with our existence. Perhaps a more significant point is how long Earth has had life. As mentioned by the OP of this thread

We know that life on earth arose almost immediately after the Late Heavy Bombardment, which is probably just about as early as it was able to exist.

From studying the fossil record we know it is possible for a habitable planet to lack intelligent life. Earth has been like that for nearly all its history. We also know it is possible for a habitable planet to be inhabited by unicellular life only. Earth was like that for billions of years. So there would be little reason for surprise if we find another world with life but no intelligent life, or if we find one inhabited by unicellular life only.

What we don't know is whether there is, or ever has been, a habitable world uninhabited by anything. It is logically conceivable, yes. But there is, as yet, no empirical example of such a world. If we find one, it will be a scientific breakthrough -- we will then know that the probability of life on a habitable world is less than 1.

[ZunarJ5]

Disclaimer - This thread has a lot of material... I'm pretty sure this post isn't covering old ground, but I may have missed something.

Something that may be significant when figuring the probabilities or determining the logic either for or against the existence and/or frequency of exolife; AFAIK, life has not been synthesized definitively from base chemical components. Amino acids on their own do not count. PLEASE, correct me if I am wrong, I would be fascinated to find out if I am.

If this is true... why? There must be something we are missing in either our assumptions about he conditions of primordial Earth or about the basic components of life. If we have the right materials, and we have the right conditions... shouldn't we be able to create life? What am I missing?

[Colin Robinson]

Disclaimer - This thread has a lot of material... I'm pretty sure this post isn't covering old ground, but I may have missed something.

Something that may be significant when figuring the probabilities or determining the logic either for or against the existence and/or frequency of exolife; AFAIK, life has not been synthesized definitively from base chemical components. Amino acids on their own do not count.

You're right -- the simplest known life is vastly more intricate that amino acids. And there hasn't been a full laboratory demonstration of how it got started.

If this is true... why? There must be something we are missing in either our assumptions about he conditions of primordial Earth or about the basic components of life. If we have the right materials, and we have the right conditions... shouldn't we be able to create life? What am I missing?

A somewhat similar point actually was raised earlier in this thread by chrisz. Van Rijn responded:

I would argue that we can't say very much about that based on current laboratory experiments. These laboratory experiments are extremely small scale compared to the planet over geological periods. Now, if you were conducting experiments with something like the volume of the Pacific Ocean, and you couldn't get results after a few hundred million years, then you might have a significant argument.

[primummobile]

Disclaimer - This thread has a lot of material... I'm pretty sure this post isn't covering old ground, but I may have missed something.

Something that may be significant when figuring the probabilities or determining the logic either for or against the existence and/or frequency of exolife; AFAIK, life has not been synthesized definitively from base chemical components. Amino acids on their own do not count. PLEASE, correct me if I am wrong, I would be fascinated to find out if I am.

If this is true... why? There must be something we are missing in either our assumptions about he conditions of primordial Earth or about the basic components of life. If we have the right materials, and we have the right conditions... shouldn't we be able to create life? What am I missing?

I agree with Colin's take on this. I would like to add that I'm inclined to believe that life arose more than once on the ancient earth, and that most of those were simply not viable long enough to develop a stable population and so did not survive. While our physical laws do govern how things can happen, I also think that the seemingly random nature of the universe also has something to do with what things do happen. There's nothing to say that RNA-based molecules are the only form of life that initially arose, and I'd be surprised if that was the only kind because when something is random (as I believe it was) it's unlikely for there to be only one possible solution. The only thing you can expect is a best solution, or to put it better, a more successful solution.

So, it's possible that we could develop life in a laboratory and simply not recognize it as life because we weren't looking for the right thing. Also, as Colin said, when we talk about the early earth, we're talking about geological time scales. What is a blink of an eye to the Earth is a very long time to us. I think we haven't been able to produce life in the laboratory because in those time scales many different things can happen that we aren't accounting for.

[primummobile]

Yes, we know that our physical laws (if they are a true reflection of reality) do not preclude the possibility of life. My preferred approach, however, is not to attempt a statistical inference from the fact that there's life on Earth but rather, to look at the physical laws and how they make life possible. It is this how-question that I find more interesting than the question of whether or not other life exists. Initially, I think that some kind of simple model must be constructed based on these physical laws or perhaps much simpler laws. Then, "life" must be defined, beginning with a simple definition e.g. life is any structure that can self-replicate and evolve. The model must then be adjusted until "life", as defined emerges. But, the life-outcome must emerge implicitly, and not be explicitly coded within the model. Once such a simple model is discovered, it can be studied further mathematically so that a more general abstract theory can be developed and further refined through application to empirical reality.

You're probably familiar with the field of artificial life, where life-like phenomena in the form of computer simulations are studied. What I would like to see in such studies is an example of artificial abiogenesis, where self-replicating and evolvable artificial organisms emerge from a system wherein no artificial organisms existed prior to emergence. Such a model, even if just a toy-model, should give some valuable insights into the general nature of abiogenesis.

I didn't reply to this earlier because I am a little confused by the last part. When I think of something artificial, I am thinking of something created by another entity. So, I'm not sure how that something arising spontaneously could be considered artificial. I think you could be getting at something a little different, but you probably need to elaborate on what you are saying, if you would.

As to the other, I understand what you are saying. But I think that the first step is establishing that our physical laws don't preclude life elsewhere. When that is established we may speculate on the genesis of other life. But I am a pessimist in that regard. I'm not naturally inclined to look for the path. Rather, I am inclined to look for the roadblocks on the path. I think a combination of both approaches is probably the best.

[Paul Wally]

I didn't reply to this earlier because I am a little confused by the last part. When I think of something artificial, I am thinking of something created by another entity. So, I'm not sure how that something arising spontaneously could be considered artificial. I think you could be getting at something a little different, but you probably need to elaborate on what you are saying, if you would.

It would be artificial in the sense that some algorithms are defined in a computer program. It was discovered that in some of these programs very simple rules of interaction between multiple agents can lead to complex pattern formation, for example Conway's game of life cellular automata. So the purely mathematical discovery is that some simple rules of interaction can lead to complex pattern formation.

I take it that with "something arising spontaneously" you refer to what I said about artificial abiogenesis. What I mean by that is not actual life in the real world, but something emerging purely from within the computer program, as I explained above with complex pattern formation. But firstly, "life" must be defined. Initially, I think, this definition is not going to be the actual definition of life (in the real world) but a very oversimplified definition. The idea is to define certain rules and then to see whether life, according to the oversimplified definition emerges from those rules. Once a model like this is discovered, in a sense, it could then be studied mathematically in order to get some kind of mathematical concept of the emergence of life-like phenomena.

As to the other, I understand what you are saying. But I think that the first step is establishing that our physical laws don't preclude life elsewhere. When that is established we may speculate on the genesis of other life. But I am a pessimist in that regard. I'm not naturally inclined to look for the path. Rather, I am inclined to look for the roadblocks on the path. I think a combination of both approaches is probably the best.

My approach would be to do the above kind of general mathematical/computational study and then to apply the generic concepts learned in that study to the specific physical laws. This approach might help with establishing whether our physical laws don't preclude life, as you say. I'm more inclined to look for a path! Any path will give us something to study mathematically, and perhaps give us some idea as to what the path/s might be. I'm not quite clear on what you mean by "roadblocks" though; could you perhaps clarify that concept for me?

[primummobile]

My approach would be to do the above kind of general mathematical/computational study and then to apply the generic concepts learned in that study to the specific physical laws. This approach might help with establishing whether our physical laws don't preclude life, as you say. I'm more inclined to look for a path! Any path will give us something to study mathematically, and perhaps give us some idea as to what the path/s might be. I'm not quite clear on what you mean by "roadblocks" though; could you perhaps clarify that concept for me?

I was hoping you wouldn't ask me to clarify that! But I'll try. While you are looking for the path, I am taking any path you find and examining it for problems. My wife tells me that I am a "Debbie Downer", but I don't think I am. I think people like me are needed because being a pessimist allows me to see things other people might miss. At the same time, I may not see the way to get there because I'm hung up on the problems. That's why I said that a combination of the two works best.

I'm not saying that your approach is not valid, or that I don't ever do that. I'm just saying that I'm inclined to look at it as "why couldn't this happen" as opposed to "how could this happen". If I am able to establish first that there is nothing saying something couldn't happen, in this case-the emergence of life- then I am free to look at it how it could happen.

We're probably getting too bogged down in the details here.

I do have comments to make about the artificial thing, but you need to let me stew on them for a while. I do find it interesting, though... and it is something I have given thought to.

[headrush]

I was hoping you wouldn't ask me to clarify that! But I'll try. While you are looking for the path, I am taking any path you find and examining it for problems. My wife tells me that I am a "Debbie Downer", but I don't think I am. I think people like me are needed because being a pessimist allows me to see things other people might miss. At the same time, I may not see the way to get there because I'm hung up on the problems. That's why I said that a combination of the two works best.

I'm not saying that your approach is not valid, or that I don't ever do that. I'm just saying that I'm inclined to look at it as "why couldn't this happen" as opposed to "how could this happen". If I am able to establish first that there is nothing saying something couldn't happen, in this case-the emergence of life- then I am free to look at it how it could happen.

We're probably getting too bogged down in the details here.

I do have comments to make about the artificial thing, but you need to let me stew on them for a while. I do find it interesting, though... and it is something I have given thought to.

I agree with your point of view. If one is to succeed in a venture, it is important to examine the potential for failure. Otherwise time is wasted in redesigning later to overcome such issues. Some people see that as a negative attitude, I see it as profoundly positive, because the job gets done more quickly and is more likely to be successful. I like to do a job properly.

But then some people I know say I have an attitude problem. When describing events at work I might say " I was performing this task when I was interrupted and had to perform another task". They then say that the other task was more important so my use of the term "interrupted" indicates my focus is wrong. Not at all, interrupted is interrupted. Words have taken on too many social aspects and connotations to be really as useful as they could be, which is why maths is the language of science.

I would say there is no logic in assuming the nonexistence of ET life. The main question might be better phrased as - how many times has life arisen in the universe ?
Then we get down to the argument over the difference between one and at least one. For myself, at least means the minimum, which in this case is one So I would answer, life has arisen in the universe at least once.
We don't know any more, so that is a fair statement. It would not be fair to say only once, without exploring the entire universe. Only implies a conclusive figure, unless you qualify it with "that we know of".
Let the semantics begin (again) :-)

[primummobile]

I agree with your point of view. If one is to succeed in a venture, it is important to examine the potential for failure. Otherwise time is wasted in redesigning later to overcome such issues. Some people see that as a negative attitude, I see it as profoundly positive, because the job gets done more quickly and is more likely to be successful. I like to do a job properly.

But then some people I know say I have an attitude problem. When describing events at work I might say " I was performing this task when I was interrupted and had to perform another task". They then say that the other task was more important so my use of the term "interrupted" indicates my focus is wrong. Not at all, interrupted is interrupted. Words have taken on too many social aspects and connotations to be really as useful as they could be, which is why maths is the language of science.

I would say there is no logic in assuming the nonexistence of ET life. The main question might be better phrased as - how many times has life arisen in the universe ?
Then we get down to the argument over the difference between one and at least one. For myself, at least means the minimum, which in this case is one So I would answer, life has arisen in the universe at least once.
We don't know any more, so that is a fair statement. It would not be fair to say only once, without exploring the entire universe. Only implies a conclusive figure, unless you qualify it with "that we know of".
Let the semantics begin (again) :-)

I don't have any semantics arguments for you, especially since we agree. If you don't have "negative" people looking for problems you can waste a lot of time on a path that will turn out to be fruitless.