On the Origin of Life and Falsifiability

A progenote population lacking proteases, ABC transporters, nucleases, and a variety of catabolic enzymes would be rather quickly exterminated by galactic cosmic rays.

Unless they had something else that would fulfill the same function. Do we really know enough about metabolism to say that only the things you've listed would suffice, and nothing else? And can we say that this something else, the nature of which we can't even guess at, must necessarily have been conserved from FUCA to LUCA under conditions of which we know almost nothing?

By my understanding the RNA World simply postulates that RNA-based replicators preceded DNA-based life. That is certainly general, and I would not expect it to be falsifiable (excepting effective falsification through the weight of problems) given the limitations of the evidence available (other than evidence that lead to it's formation.

Okay. So then, in your view, the RNA world is -- by virtue of its general nature -- not falsifiable except through the accumulation of extensive problems. Yet lithopanspermia is also a rather general model, but as I have argued (contentiously, given objections raised by Dr Adequate), it is falsifiable in the Popperian sense. Thus it would seem to me your primary objection here is that Popperian falsificationism is not an ideal criterion for demarcation of science and non-science. Is this basically correct?

If, for instance, RNA replicators turned out to be impossible, as seems to have been widely assumed at one time the RNA World would have been clearly falsified.

That's a pretty terrible way to falsify a hypothesis, since there's no experiment that can potentially demonstrate that RNA replicators are impossible.

What kind of assumptions would be made? Why would you even ask?

Because I am genuinely curious if you have discovered assumptions built into lithopanspermia which I am not aware of. However, you appear to prefer a more combative than explorative approach to discussion.

If you can show that life could get from any or all of the planets in your count to Earth without making additional assumptions please make the case. If you can't then you may as well concede the point. Asking me to concoct scenarios whereby it could happen seems to be an obvious diversion of no worth.

So you think there might be particular assumptions in lithopanspermia but you can't establish that. Mmk.

And if you produce a scenario including abiogenesis that can be evaluated as a who,e we could do that. But until you do, the process of abiogenesis itself can't be compared, and therefore should remain off the table.

There is evidence that there was a considerable number of life-friendly planets at the time of Earth's origin, which means that abiogenesis would have had more time to occur. This is a rather straightforward argument that panspermia increases the probability of abiogenesis.

So let me re-phrase: why is the evidence for the panspermia hypothesis generally of a historical nature, in contrast to the RNA world and metabolism first models? That seems obvious. Panspermia leaves out the difficult problem of abiogenesis altogether. If you tried to include it you would find a mu he greater need for possibility-based work. For instance, trying to identify plausible settings where abiogenesis would be easier.

How does this address my question that the evidence for panspermia is historical in nature, in contrast to the evidence for the RNA world and metabolism first models? You're response seems to boil down to: "Well, panspermia doesn't address abiogenesis." That appears to be a bit irrelevant to my question. Please elucidate further so I understand what your argument here is.

Giving people money just because they favour a particular idea certainly seems to be a poor way of generating useful research. Do you disagree with that ?

No, but that's not what I'm saying, is it? Do you believe that pursuing panspermia research is a dead-end for pragmatic purposes?

Edited by Genomicus, : No reason given.

First, we have the obvious double standard of demanding that the RNA world and metabolism-first ideas be generally falsifiable while panspermia need only provide falsifiable scenarios. No general falsification for panspermia has been proposed.

What do you mean by "generally falsifiable" in contrast to "falsifiable scenarios"?

Second my point that falsification of such general models effectively occurs when the problems become overwhelming has not really been answered. Following the Duhem-Quine thesis it is usually impossible to falsify general theories, since auxiliary hypotheses can be generated to protect them from falsification (e.g. The epicycles of Ptolmaic cosmology). Given that the falsification I propose is exactly what we'd expect to be required (and both the complexity of the problem and the paucity of evidence add to that) I can't say that there is truly a problem which would lead us to prefer investigations of another model on purely philosophical grounds - the more so since naive falsificationism is hardly considered to be good philosophy in the first place.

Karl Popper anticipated the Duhem-Quine thesis in his formulation of the falsifiability criterion for scientific hypotheses. The criterion of falsifiability does not exist in a vacuum; it's part of a broader methodological ecology in which the following conventions are adopted:

"Scientific hypotheses are falsified when we accept existential statements that contradict them. We should, however, demand, when possible, that results are reproducible and inter-subjectively testable. If additional experiments are impracticable, such as in the case of natural experiments, then we should at least want to specify conditions of reproducibility. Stray or fleeting results which fail to satisfy these criteria, while perhaps hinting at a problem or inspiring new research, aren’t to be regarded as falsifications.

"We should refrain from what Popper calls ‘conventionalist stratagems’. That is, ad hoc maneuvers to evade falsification, such as changing definitions, accusations of deceit, dismissing results as observational errors or equipment malfunction. Bare appeals to doubt, or the mere logical possibility of false auxiliary hypotheses aren’t acceptable objections to an apparent falsification.

"If we wish to defend scientific hypotheses from a putative falsification, then we must structure our objections as independently testable hypotheses, or modifications to hypotheses should increase their degree of falsifiability. In other words, if an objection merely papers over the problem, serving no purpose other than to quarantine or excuse the apparent failure and thereby reduce explanatory content, then it has no scientific merit." From: here.

Auxiliary models can only patch up a hypothesis in crisis for so long, and these auxiliary models must increase the degree of falsifiability of the hypothesis in question; otherwise, the auxiliary models increasingly move the general hypothesis away from the domain of science.

By your argument, however, it seems that only the weight of difficulties can bring down the edifice of a hypothesis. But this seems like a pretty poor criterion of demarcation between science and pseudoscience. A "weight of difficulties" can be found in creationism (for which there does not appear to be a compelling falsification scenario), so is creationism therefore science in some way?

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Okay. So then, in your view, the RNA world is -- by virtue of its general nature -- not falsifiable except through the accumulation of extensive problems. Yet lithopanspermia is also a rather general model, but as I have argued (contentiously, given objections raised by Dr Adequate), it is falsifiable in the Popperian sense. Thus it would seem to me your primary objection here is that Popperian falsificationism is not an ideal criterion for demarcation of science and non-science. Is this basically correct?

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I don't see that lithopanspermia is that general at all. The idea that something akin to existing life travelled on a meteor seems to be quite specific compared to considering the interactions of RNA molecules in all the possible environments found on primordial Earth

And I would say that your statement is sufficiently lacking in nuance to be considered potentially misleading. Thus I am not prepared to agree with it.

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That's a pretty terrible way to falsify a hypothesis, since there's no experiment that can potentially demonstrate that RNA replicators are impossible.

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Certainly not by exhaustive trial, but we could say that for almost anything.

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Because I am genuinely curious if you have discovered assumptions built into lithopanspermia which I am not aware of. However, you appear to prefer a more combative than explorative approach to discussion.

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I can't see that asking completely irrelevant questions adds to the discussion. Or that pointing out that they are irrelevant should be considered combative.

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So you think there might be particular assumptions in lithopanspermia but you can't establish that. Mmk

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No. as I said, if you wish to show that you don't need any extra assumptions it is up to you to offer your explanation. That you choose to divert and evade instead suggests that you don't have any such explanation.

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There is evidence that there was a considerable number of life-friendly planets at the time of Earth's origin, which means that abiogenesis would have had more time to occur. This is a rather straightforward argument that panspermia increases the probability of abiogenesis.

How does this address my question that the evidence for panspermia is historical in nature, in contrast to the evidence for the RNA world and metabolism first models? You're response seems to boil down to: "Well, panspermia doesn't address abiogenesis." That appears to be a bit irrelevant to my question. Please elucidate further so I understand what your argument here is.

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I haven't really seen much in the way of evidence, but the fact that panspermia has lower theoretical content in relation to historical claims rather suggests that a greater proportion of the evidence should be historical.

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No, but that's not what I'm saying, is it? Do you believe that pursuing panspermia research is a dead-end for pragmatic purposes?

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But it's been my point and one you seem to have been disputing. I really make no judgement over whether panspermia is a dead end, and making the point that research needs to be proposed before it is funded hardly seems to suggest that I do.

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What do you mean by "generally falsifiable" in contrast to "falsifiable scenarios"?

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I mean that falsifying lithopanspermia does not in itself falsify panspermia.

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By your argument, however, it seems that only the weight of difficulties can bring down the edifice of a hypothesis. But this seems like a pretty poor criterion of demarcation between science and pseudoscience. A "weight of difficulties" can be found in creationism (for which there does not appear to be a compelling falsification scenario), so is creationism therefore science in some way?

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No, I mean that - among other reasons - creationism is not science because it HAS been brought down by the weight of difficulties, at least so far as scientific investigation is concerned.

By your argument, however, it seems that only the weight of difficulties can bring down the edifice of a hypothesis. But this seems like a pretty poor criterion of demarcation between science and pseudoscience. A "weight of difficulties" can be found in creationism (for which there does not appear to be a compelling falsification scenario), so is creationism therefore science in some way?

No, but it had the potential to be. The proposition that there is an elephant in my house is not science, but it is a meaningful proposition, it's the sort of proposition that had the potential to be a scientific fact, and it is susceptible to scientific investigation. Like creationism, it is falsifiable and false.

Edited by Dr Adequate, : No reason given.

kbertsche writes: All that you are decribing here is "data analysis". Science involves data analysis, of course, but so do many endeavors outside the world of science. Science is much more than just data analysis!

Science analyzes data in one direction and ID analyzes data in the opposite direction - which is why ID can be said to be the opposite of science. There's no need for you to nitpick about such an obvious distinction.

Hi, Kbertsche.

kbertsche writes: ringo writes: Science is the process of going from data to conclusions. All that you are describing here is "data analysis".

That's true, but since the "data analysis" part is the part Ringo identified as differing for science and ID, what exactly is the problem with that?

kbertsche writes: Science proceeds by abduction; it starts with one or more theories (which could be viewed as "potential conclusions") and collects data in an attempt to prove one or more of these theories false. Hopefully one theory will be verified and will be tentatively concluded to be correct.

Since we're in the game of philosophical nitpicking, science doesn't start with theories: it starts with hypotheses (or propositions), and the iterative process of the scientific method is what eventually turns a subset of those hypotheses into theories, while discarding the remainder.

For creationism/ID, the process doesn't really begin with a hypothesis or proposition: it begins with an axiom, and the data is evaluated or rejected based on its conformity to that axiom. It's "conclusion first, even at the expense of data."

To bring this back toward the topic, one of the major failings of Intelligent Design and creationism is the falsifiability criterion: objections or divergences from the predictions of the creation hypothesis are only used as a basis for obscuring or interpreting away shortcomings in the hypothesis, and not for evaluating the accuracy of the overall Design concept, which is what makes it an "axiom."

Genomicus is proposing that several mainstream OoL hypotheses could fall into this same trap. The RNA World Hypothesis seems particularly popular these days, and Genomicus's objections to it are one way of trying to "keep the science honest," so to speak. This is part of the evaluation process: Genomicus is trying to make sure we only consider valid, testable propositions, and he's challenging our hypotheses on those grounds. Ultimately, I think he's just got some bits of the philosophy wrong, but he still deserves a lot of credit for showcasing how science is different from creationism: we consider and reconsider our propositions fastidiously, just as Ringo said.

It is a splendid argument, because if something is impossible, then the probability of it happening is 0 -- or, at least, extraordinarily close to 0. So, for example, you can argue that your door has x*y dimensions, and the elephant would be too large to fit through this doorway. You can then point to the structural integrity of the walls surrounding the doorway, citing its Young's modulus and so on. Then you can say that the elephant's musculature and biomechanics would not have allowed for this Proboscidean creature to generate sufficient force to squeeze through the doorway. All of these would be very rigorous arguments that would rule out the possibility that the elephant was in your house while you shopped. So this sort of argument is a perfectly valid method of falsification.

Yes, provided that somewhat rigorous quantification takes place, instead of merely asserting that "Phenomenon X is implausible."

If you can propose or cite equally rigorous experiment or series of experiments that could potentially falsify the RNA world or metabolism first scenarios, then I will gladly concur that these models are falsifiable. If you can show that in principle no such discoveries could ever be made, even if the RNA world did not exist and could not have existed, then I will gladly concede that it is unfalsifiable.

But the burden of proof isn't really on me. A hypothesis should be falsifiable, at least if we adopt Popper's view of what constitutes a scientific hypothesis (a view, incidentally, that has been adopted by quite a large number of philosophy of science experts). No one should have to prove the negative view that a hypothesis is not, in principle, falsifiable. Instead, the specific details of how a hypothesis could potentially be falsified must be outlined if a hypothesis is to be considered scientific in the strictest sense.

Because in the case of lithopanspermia our reasoning is very well-grounded in the radiobiology of microbes. Now all you have to do is learn an equal amount about the biochemistry of RNA, and you're all set. If all your argument boils down to is that we should prefer lithospermia to the RNA world because in our present state of knowledge we'd be better able to falsify one than the other, then from the point of view of epistemology that's hardly significant.

That's quite significant, actually. If, on the one hand, we have a hypothesis (lithopanspermia) that's directly falsifiable -- this is certainly preferable to a model full of knowledge gaps that render it unfalsifiable. This is not to say that these gaps will not be filled or that exploratory science of this model should not take place; there is a good deal of value associated with any serious attempt to resolve the enigma of how life arose. But a model full of knowledge gaps that make it unfalsifiable does not necessarily qualify as a scientific hypothesis compared to a model which is plainly falsifiable.

Before the invention of the microscope, was the hypothesis that Jews caused epidemic diseases preferable in principle to the idea that tiny little organisms caused epidemic diseases? The former was potentially much easier to falsify in practice, given the state of science in that era, because it was much easier to observe the activities of Jews than of these tiny organisms ... but did that make it somehow more scientific?

The "hypothesis" that Jews caused epidemic diseases would never have qualified as a scientific notion as there was no supporting evidence for this view. I am not aware that there ever existed a scientific consensus of the above idea because it was quite patently non-scientific and not backed by any evidence (popular myth notwithstanding). So you may want to come up with another example with which to frame your argument.

A progenote population lacking proteases, ABC transporters, nucleases, and a variety of catabolic enzymes would be rather quickly exterminated by galactic cosmic rays. Unless they had something else that would fulfill the same function. Do we really know enough about metabolism to say that only the things you've listed would suffice, and nothing else? And can we say that this something else, the nature of which we can't even guess at, must necessarily have been conserved from FUCA to LUCA under conditions of which we know almost nothing?

Wait. So in your effort to demonstrate that lithopanspermia is not falsifiable, you're divining the possible existence of analogs of proteases, ABC transporters, and nucleases, which would have then been lost under mysterious selective pressure that somehow allowed such a loss to not affect the reproductive fitness of the population in a negative way, and wherein no homologs were preserved; and then cells evolved proteases, ABC transporters, and nucleases. I must be misunderstanding your argument, because otherwise you're straining credulity at its seams.

Could you please find another way to phrase your argument so it's clearer to me? Thanks.

I don't see that lithopanspermia is that general at all. The idea that something akin to existing life travelled on a meteor seems to be quite specific compared to considering the interactions of RNA molecules in all the possible environments found on primordial Earth.

The RNA world hypothesis:

Free-floating nucleotides stochastically assembled into short sequences with catalytic properties --> Primitive catalysis propelled the generation of ever-longer nucleotide sequences --> Base-pairing coupled with thermal and catalytic activity allowed for polynucleotide replication --> Replication lead to molecular evolution and increased efficiency of RNA catalysts --> Catalytic RNAs allowed for extensive peptide bond formation among amino acids --> Primitive protein molecules thereby emerged, which eventually evolved into the sophisticated protein machinery of modern cellular life. The RNA-to-protein system was also upgraded to a DNA --> RNA --> protein system.

The Lithopanspermia hypothesis:

Biological life emerged on another planet, rich with organic chemical resources around the time of the origin of the Earth --> Much of this microbial life evolved sophisticated machinery for resistance against ionizing radiation --> Ejecta from this planet following an impact contained members of these microbes --> This ejecta traveled through space and eventually struck Earth at approximately 3.6 Ga.

How again is the RNA world model more general than lithopanspermia?

Certainly not by exhaustive trial, but we could say that for almost anything.

So then if not by exhaustive trial, how?

I haven't really seen much in the way of evidence, but the fact that panspermia has lower theoretical content in relation to historical claims rather suggests that a greater proportion of the evidence should be historical.

And the reason panspermia has lower theoretical content in relation to historical claims is what?

But it's been my point and one you seem to have been disputing. I really make no judgement over whether panspermia is a dead end, and making the point that research needs to be proposed before it is funded hardly seems to suggest that I do.

Well, I certainly agree with you that research needs to be proposed before it's funded. But I'm also saying that such research should be proposed for panspermia largely because the alternative models for the origin of life are considerably unfalsifiable, and therefore more exploratory than pragmatic in a scientific sense.

I mean that falsifying lithopanspermia does not in itself falsify panspermia.

Sure, and falsifying the RNA world model does not in itself falsify abiogenesis. If you have a falsification scenario for the RNA world model, by all means present it. I will then immediately concede that the RNA world model is falsifiable.

No, I mean that - among other reasons - creationism is not science because it HAS been brought down by the weight of difficulties, at least so far as scientific investigation is concerned.

Really? Let's take the age of the Earth, for example. No matter how much evidence is presented that the Earth is approximately 4.5 Ga, the creationist can always resort to a divine mechanism (and they have) which accounts for observations of isotope-based dating. You will find that creationists can always account for a particular observation by inserting a divine mechanism, so the weight of the evidence seems to be of no weight at all! The blade that slices creationism away from the domain of science must therefore be the criterion of falsifiability. It is falsifiability, not the weight of evidence, that most starkly divides science from pseudoscience.

No, but it had the potential to be. The proposition that there is an elephant in my house is not science, but it is a meaningful proposition, it's the sort of proposition that had the potential to be a scientific fact, and it is susceptible to scientific investigation. Like creationism, it is falsifiable and false.

I'll just reiterate what I said to PaulK in Msg 57:

Really? Let's take the age of the Earth, for example. No matter how much evidence is presented that the Earth is approximately 4.5 Ga, the creationist can always resort to a divine mechanism (and they have) which accounts for observations of isotope-based dating. You will find that creationists can always account for a particular observation by inserting a divine mechanism, so the weight of the evidence seems to be of no weight at all! The blade that slices creationism away from the domain of science must therefore be the criterion of falsifiability. It is falsifiability, not the weight of evidence, that most starkly divides science from pseudoscience.

Edited by Genomicus, : No reason given.

Well, that's the Duhem-Quine thesis made flesh, isn't it? We can save the appearances for any hypothesis by postulating the existence of an omnipotent being who used his miraculous powers in such a way as to lead us to false conclusions.

For example, whatever we discovered about LUCA's ability to resist radiation, we could say: "But maybe lithospermia is still true, but maybe there is a God who in his infinite wisdom used his mighty powers to screen FUCA from radiation in its passage through the cosmic void". And now lithospermia is unfalsifiable too. Likewise, the proposition that there was an elephant in my house, which you agreed was falsifiable, becomes unfalsifiable --- because what if God teleported the elephant in and then out again without it having to pass through any of the doors?

In order to use the idea of falsifiability at all, we have to rule out, methodologically, such things as a (willfully or inadvertently) deceitful God, the Cartesian demon, and the brain-in-a-jar hypothesis as the sort of auxiliary hypotheses that people are allowed to propose.

Edited by Dr Adequate, : No reason given.

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How again is the RNA world model more general than lithopanspermia?

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Strictly speaking lithopanspermia doesn't include abiogenesis so much of what you said is irrelevant. And I would say that the whole "travel to earth on a meteorite" - which is the only part you offer as falsifiable - is quite specific.

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So then if not by exhaustive trial, how?

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By showing some restriction that cannot be overcome.

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And the reason panspermia has lower theoretical content in relation to historical claims is what?

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Because it doesn't include abiogenesis. If it did *that* part would be even less historical than earthly abiogenesis research.