Atreyu:
That's absurd. The laws of gravity do not change over time.
They most certainly do. We went from Aristotle, through Kepler to Newton, to Einstein and beyond. The law of gravity has indeed changed to fit a wider and wider set of observations. Each law subsuming the previous one as a special case, for a particular subset of observations.
Neither do the laws of biology, geology, or anything else. In fact, laws are defined to be constant truths which can be used to predict outcomes in specific scenarios.
As I said, they are arrived at by Induction. They are generalisations
from a specific finite set of observations. We see a load of white swans. We haven't yet seen swans of any other colour. So we pronounce "all swans are white". So it is one of their most important characteristics that they are
always provisional - always subject to possible falsification. The proverbial black swan.
If you look around you and observe that you never see a living thing emerge from anything other than another living thing, you may quite reasonably pronounce "living things always emerge from other living things". But that is
provisional.
If we don't see cells 'arising from the muck' today, we have every reason to think they did not a few billion years ago.
How about, say, 10 billion years ago? Before the Earth existed?
No, laws are universal and constant, hence their designation as laws in the first place.
As I said, they are
provisional. Revisit the basics of the scientific method and Inductive Reasoning.
Steve3007:
The reason to believe [that at some point in the past life came from no-life] stems from the basic fact that at some point in the past there was no life and now there is.
Atreyu:
That line of reasoning is atrocious. Yes, at some point there was no life (as we know it) on Earth, and then there was. That doesn't mean the laws of nature were different back then.
I didn't say that it did mean that. I have no reason to believe that the laws of
physics were different back then. But the line of reasoning is about as simple and sound as it gets: if life didn't exist at one time and did exist at a later time, then at some point between those two times it came into existence.
There are plenty of other explanations. Migration is the first that comes to mind.
That's not another explantion! It just shifts the question of the origin of life to a different location! Yes, it's perfectly possible that the elements of life, or even simple life forms, came to Earth on meteors or whatever. But then you have to admit that at some point in the past those meteors did not exist, just as at some point in the past the Earth did not exist. So where did the life on the meteors come from?
If you think that life could not possibly have developed from non-living matter then you really do only have two options:
1. It has existed forever.
2. It was created ex nihilo. Maybe by a Deity.
Which is it?
No, we don't know. But we should regard it as highly unlikely that the basic laws of biology were radically different in the past.
I agree that it seems probable that the physics of the universe operated the same in the past as it does now. The evidence for that is such things as the formation of stars. That doesn't mean that life has always existed. If you don't believe that life has always existed, then you believe that at some point in the past there was no life. Therefore there were no "laws of biology". There were laws of physics, on which the laws of biology rest. Do you think that the laws of biology do not rest on the laws of chemistry and physics?
We should stick with the basic premise that life only comes from other life, and see where that takes us in our search for the origin of life on Earth.
You're free to stick with that premise. The only two possible conclusions are the ones that I listed above. The only place it takes us with regard to life on Earth is that it was carried here from elewhere. But, as I said, that just shifts the question of the origin of life to elsewhere.
Sure, we should try to falsify propositions, but if abiogenesis were true, why can not science prove it in the laboratory by creating life from non-life? That would be an excellent way to falsify it. But it cannot be done. More evidence that life can only come from other life.
Yes, it would be an excellent way, and yes it has not yet been done, although a lot of progress has been made. Some of the fundamental chemical building blocks have been made.
If you think that it is fundamentally impossible, no matter how hard anybody tries, then presumably you think there is something about the particular molecules that are associated with living things (DNA, sugars, proteins etc) which makes them completely different from other molecules and impossible to construct from anything other than other biological molecules? If so, what is it? What is it about DNA, for example, that would make it impossible to construct, even in principle, from its constituent atoms?
Science could never recognize it because any recognition is beyond empiricism. There is no way to verify the Earth is alive because there is no way to make any sort of psychic connection with it.
I've no idea what you mean by a "psychic connection", but clearly the question of whether Earth is a living thing is an empirical one, so long as you define what you mean by the words that you're using. That's where the debate comes in, it seems to me - the defintion of words. For example, is a colony of ants a living thing? Or is it a collection of living things? Is the Earth a living thing, or a collection of living things? What's the difference?
My "modified" definition of life is an entity with awareness and an ability to react to changes in its environment, i.e. a sentient being.
OK. fine. So you take the abstract concept of sentience as defining life and take away the specifics of the hardware. A bit like considering computer software without caring about the physical medium in which it is stored. That's ok with me, as long as you state that this is your understanding of the word "life", as you have done here. So other people can be clear that it differs from their definition.
The next problem, then, is defining and identifying sentience.
Armed with that basic definition of non-carbon based life will in no way help us to recognize it, beyond the life forms in which we already do.
It sounds like a definition of life that
could be carbon based but isn't necessarily. The chemical medium (the carbon) is not relevant to you. OK.
What we call "life" is the sentient beings which we can recognize as such, all of which happen to be carbon-based, as we are.
Yes, obviously we generally tend to define things by example. The only way we can define life, and indeed the only way we can define sentience, is by pointing to examples of it and trying to capture what properties those examples have in common.
Sentient beings which we might not recognize must be so much different than life which we do recognize, that they must not be 'carbon-based'. The Earth, if it is indeed a sentient being, would be one of those entities.
I don't see how they
must not be carbon based. But I take the point. They
need not be carbon based.
If you define life as "that which is sentient" and you also define Earth as sentient, then clearly Earth = life. you don't even need to know what "Earth", "Life" and "Sentient" are to see that. It's a simple syllogism.
I defined "life" above, in a more broad and encompassing way, but not in a way in which it becomes just a "vague metaphor". There is nothing vague or metaphorical in my definition of a sentient being.
So how do you define sentience? You've already proposed that it's difficult to spot - difficult to tell whether any given entity has the property "sentience".
However, I'd like to give you an example, since you brought it up, of how considering the Universe as a gigantic living thing could explain one of our observations, and one which perplexes the scientific community. What if the reason why the Universe is expanding at an accelerating rate, beyond what it should without inventing "dark matter", is because the Universe Itself is willing it to happen? Thinking of the Universe as a living being gives us a new force with which to explain phenomena - Will or Intention (in the "cosmic" sense of the terms). Things can happen not just because of an interaction of mechanical laws and forces but also because conscious entities intend them to. We can try and reduce those conscious tendencies to mere mechanical laws, or we can acknowledge that they are beyond them....
So the universe is expanding because it wills it to happen? Perfectly possible, but not very interesting unless it is possible to, as it were, psychoanalyse the universe! If it is part of the definition of the free-will of a sentient being that it has no underlying mechanism, then what you're saying is really no different from saying that everything happens in the universe because it is the will of a deity that it should happen. It is not for us to question why. It is His will.
You can say that about the expansion of the universe if you like. You could equally say it about everything else for which we have no idea of an underlying mechanism (yet). A sort of "will of the gaps". Just not very interesting, in my opinion, because it shuts down any further enquiry. I quite like enquiry.