Big News: The Plausibility of Abiogenesis Has Been Experimentally Demonstrated

From earliest recorded history mankind has wondered how life on earth first arose.  The current diversity of life on earth is spectacularly well-explained by Darwinian (or Dawkinsian) evolution, the process of replication with random variation plus natural selection.  Things that are better at making copies of themselves make more copies.  What makes something better at reproducing in one environment almost always makes it worse in a different environment.  Lungs are a big win if you live on land, gills generally work better if you live under water.  Earth has a large variety of environments, and so a variety of life has evolved to exploit them.

But this leaves a crucial question unanswered: how did this process get started?  Even the simplest living thing today is far too complicated to have arisen by pure chance.  There has been a lot of speculation and plausible hypotheses, but no actual answer.  The belief that life began as a purely naturalistic process has always required a kernel of faith.

Until now.  In the last year and a half there have been two papers published that have removed the last vestiges of reasonable doubt.  The first one was a computer model, and the second, published just three months ago, is an actual laboratory experiment.  (Here is a more accessible description.)

But before I describe these papers I want to show you a little back-of-the-envelope calculation that illustrates why they are so significant.  To kick start evolution we need to somehow make a replicator, a thing capable of making copies of itself.  In order to assess the likelihood that a replicator can arise by purely naturalistic processes we need to know two things.  First, what is the most complicated thing that could plausibly arise by pure chance, without life?  And second, what is the simplest plausible replicator?  If there is a big gap between these two, then we have a big Problem, a big gap in our explanation.

A likely candidate for a minimal replicator is an RNA molecule because RNA is a biological multi-tasker: it can both carry genetic information and catalyze chemical reactions of the sort that happen in living things.  RNA, like its close chemical cousin DNA, is a polymer, a molecule that consists of a chain of small building blocks called bases.  Both RNA and DNA have four different bases.  Three of these are the same: adenine, cytosine, and guanine.  The fourth base in DNA is thymine while in RNA it is uracil.  These are commonly abbreviated ATCG and AUCG, but these details don't really matter.  What matters is that in each case there are four different bases, and in both cases these bases are arranged in a linear sequence.  This makes it really easy to compute how many possible DNA or RNA molecules there are with a given length: it's just 4 raised to the power of the length of the chain.  (Strictly speaking you have to divide this number by two because if you take a sequence and reverse it you end up with the same molecule, but that turns out not to matter.)

It has been experimentally demonstrated that the bases that form RNA (and DNA and proteins) form spontaneously in conditions likely to have existed on earth in its early days.  It has also been experimentally demonstrated that these bases spontaneously link together to form chains.   What had not been experimentally demonstrated until now was that these spontaneously generated RNA chains could form replicators.  In fact, there seemed to be a pretty big gap between the complexity of the chains that had been formed in labs and what would be needed to self-replicate, but this was hard to assess because we didn't actually know how short a replicator could be.

It is pretty straightforward to predict what this value should be.  We start by estimating how much material we could have to work with.  Earth's current biomass, i.e. the total mass of all the organic compounds on earth is about 500 GTC (gigatons of carbon).  Note that this is only a tiny fraction of the total carbon on earth.  That figure is 1.85 billion GTC.  Only about one in a million carbon atoms on earth are part of an organic molecule.  So it is possible that the biomass of the early earth was much higher, but that will ultimately turn out not to matter.

The numbers we are about to deal with are going to get very big so it will be convenient to swtich to scientific notation.  Unfortunately, the Blogger platform doesn't make it easy to create superscripts, so I am going to use the conventional 10^X notation to denote 10 raised to the power of X.  500 GTC is 500 x 10^9 = 5x10^11 tons = 5x10^14 kilograms of carbon.  Let's be conservative and round this down to just 10^14 kg.  To get the number of carbon atoms we multiply by Avogadro's number 6x10^23, and divide by 12 (because the atomic weight of carbon is 12 —six protons and six neutrons).  Since we are just doing a very rough estimate here, we can safely ignore everything but the exponents and arrive at a final figure of (very roughly) 10^45 carbon atoms.  The RNA/DNA bases all have less than six carbon atoms, so this is enough to make 10^44 RNA/DNA bases.  Of course, not all organic molecules are RNA/DNA bases, so let's round this down to 10^40.  That's dividing by ten thousand, which seems pretty conservative.

The other thing we need to take into account is how much time we have to find a replicator.  How fast do these chemical reactions takes place?  How long does it take to stick a new base onto an RNA chain, or take one away?  We can get a rough estimate by looking at how long it takes for a living organism to reproduce.  The well-known bacteria E. coli takes about 40 minutes to reproduce, and it has 4.7 million bases in its genome.  That's about 1000 bases per second, but this is likely a serious overestimate for prebiotic earth.  Life has had billions of years to optimize its reproductive chemistry, so let's be conservative and assume that it takes a full second to build a new RNA molecule in a prebiotic earth.  There are 60x60x24x365 = 7x10^7 seconds in a year.  Again, let's be conservative and round this down to 10^7.  But then we need to multiply this by the amount of time we have to produce a replicator.  Earth is four billion years old, so if we can do it in (say) a million years that is the blink of an eye on that time scale.  So we have 10^40 bases, and 10^7 years which gives us time to do 10^14 different experiments.  Note that this is not to say that we can only try 10^14 different combinations.  All of those 10^40 bases are floating around in the primordial soup and mixing and matching and forming different sequences at the same time.  So every second we can try a huge number of combinations.  How many?  That is a little tricky to compute because we don't know how long a sequence we actually need.  Again, let's be conservative and look at the smallest currently existing natural replicators to guide us.  These are called viroids, and they have a few hundred bases.  Let's round this up to 1000.  So every second we can potentially try 10^37 different sequences.  Multiply that by 10^14 seconds and we can roll the abiogenetic dice a total of 10^50 times in a million years.

Is that enough?  If the minimal replicator that we're looking for is roughly the same size as a modern viroid, i.e. a few hundred bases, then no, it's not enough.  Not even close.  And so for a very long time the abiogenesis hypothesis relied to a certain extent on an article of faith: a replicator that is much shorter than anything that exists on earth today is possible.  Another way of looking at it is that this hypothesis made a falsifiable prediction that a much smaller replicator is possible.

For a long time there have been some good theoretical reasons for believing that shorter replicators are possible, but no actual experimental proof.  These theoretical reasons have to do with information theory and the theory of computation and a theoretical construct called a Quine.  That is a deep thicket of weeds that I want to avoid here, though it is all rather fascinating if you feel like diving in.  The bottom line is that under some not-entirely-unreasonable assumptions you can demonstrate mathematically that self-replicating systems are possible with as little as 132 bits of information, which is the equivalent of 66 base pairs.  That is easily in range of what can be achieved with 10^50 trials.  The math goes like this: suppose you have an extremely unlikely event with odds 1 in N where N is a very large number.  If you do exactly N trials then the odds that this event will occur is about 2 in 3 (the exact value is 1-1/e, about 63%).  After that the odds rise dramatically.  If you do 2N trials then the odds of the event happening are 87%.  If you do 10N trials the odds rise to over 99%.

In other words: if you do 10^50 trials, and there exists a replicator whose odds of arising by chance are better than 1 in 10^49, then you are practically guaranteed to find it.  Those are the odds for a biological replicator with about 80 base pairs (because 10^49 is approximately 4^80).

And now we have an actual experimental demonstration of an RNA replicator with 45 bases (it is called QT45).  So even if we are off in our estimate of 10^50 trials by many, many orders of magnitude (and remember that we arrived at that number by making some very conservative assumptions) it is still a virtual certainty that a replicator will arise spontaneously almost immediately (on cosmic and geological time scales) on a planet with liquid water and a biomass the size of earth's.

It is important to be clear about what this experiment actually shows.  It does not show that this is how life actually began.  It does not show that QT45 is the original replicator.  All this experiment shows is that small biological replicators are possible.  But that is enough.  If they are possible, and they are small enough (and QT45 passes the necessary threshold by a huge margin), then the spontaneous generation of replicators is inevitable.  Abiogenesis no longer requires any leaps of faith.  The details of how it actually happened are still TBD and probably always will be.  But the mere fact that a naturalistic explanation has now been demonstrated to be possible beyond any reasonable doubt completely destroys intelligent design.  As long as there was room for doubt that purely naturalistic abiogenesis was possible, there was room for a reasonable belief that some kind of intelligent designer was necessary.  But that argument has now been blown out of the water.  We no longer need to guess how small a replicator can be, nor do we need to guess how likely it was for one to arise by chance.  Now we know.

Intelligent design advocates will object to this by pointing out that this replicator did not arise in nature but was created in a lab, which was created by intelligent humans.  But this completely misses the point.  What matters here is not how this replicator was created, but the fact that it was possible to create it at all.  This replicator is almost certainly not the one that originally sparked life here on earth.  It is almost certainly not the smallest possible replicator.  It is almost certainly not the most effective replicator of its size.  It is actually not a particularly good replicator.  But it is also almost certainly not the last replicator of this size that we are going to find.  The fact that one replicator this small exists means that it is virtually certain that there are others, and that some of them will be smaller, and some of them will be better.  And yes, these things can be created simply by tossing the parts into bin and shaking them up — as long as your bin is the size of a planet and you shake for a few million years, though for obvious reasons that is not an experiment we are likely to be able to replicate.

The other paper, published last year, which demonstrated all of these things happening in a computer model is the icing on the cake.  The results here are not directly comparable to a biological system.  There are good reasons to believe that the computer model captures the dynamics of a biological system, but that is a very deep rabbit hole.  But the main takeaway is that the replicators which arose in the computer model are of comparable complexity to the QT45 replicator.

This is the last nail in the coffin of intelligent design theory.  Before these results, intelligent design could only be criticized as an argument from ignorance: just because we don't know the details of the process that produced the first replicator doesn't mean that it was not a naturalistic process.  All it means is that we have not yet worked out the details.  But now we have.  The last gap in our understanding of the naturalistic origins of life on earth has now been definitively closed.

Seeking God in Science part 6: Systems and States

In the previous two installments we talked about chairs, specifically, what distinguishes a chair from a non-chair.  We considered and rejected the "chairness hypothesis" in favor of the atomic theory, which says that chairs — and all physical objects (at least inanimate ones) — are made of atoms.  (N.B. I am actually a human, notwithstanding my fondness for em-dashes.)  What makes a chair a chair is not some mysterious metaphysical "chairness" but simply the arrangement of a bunch of atoms.  If the atoms are arranged in a way that we humans recognize as a chair, i.e. a thing that you can sit on (or at least a thing that resembles a thing that you can sit on) then it's a chair.  The line that separates chairs from non-chairs is fuzzy.

Note that although "chairness" might sound a little silly,  the idea is not quite as absurd as it might seem.  It goes back to Plato, and there are people who take this concept quite seriously.  In fact, that article I just linked to points out a potential Problem:

[S]ome modern philosophers declare that chairs dont exist at all, really there exist only “particles arranged chairwise”. Why, they say, should we privilege the particles arranged “chairwise” as being a thing but not, say, the particles arranged as “my nose + the Taj Mahal + the moon”. No, they say, there are no composite objects such as chairs, otherwise we must accept crazy, gerrymandered objects like the nose-Taj Mahal-moon. Only the fundamental particles (whatever they turn out to be) exist. Awkwardly, this means you dont exist, only “particles arranged Acerwise” [Note: this text is part of an answer to a question posed by someone named Acer], but we can still talk about chairs, plants , planets and people as if they existed. Some of us (myself for one) find it hard to accept that we don't exist..."

Personally, I think this is a straw man.  Chairs obviously exist, as does your nose, and the Taj Mahal, and the moon.  If you want to, you can aggregate all of these into a composite object and give it a name.  The nose-mahal-moon exists too.  It's not particularly useful to give that particular collection of Things a name, but there is nothing stopping you if that's your jam.  And there are examples of weird collections of Things that are useful to consider in the aggregate and so we do as a matter of course give them names: Universities.  Corporations.  Governments.  Museums.  Research laboratories.  Movie studios.  All of these consist at least partly of Things, which are made of atoms arranged in particular ways.

The question I want to begin to address now is: what else is there?  Do we need anything other than Atoms Arranged in Particular Ways to explain any of our observations?  Yes, we do.  At the very least we need light to explain the fact that we can see things.  Light is not made of atoms.  In fact, Light is some seriously weird shit.  I'll be talking a lot more about light in later installments, but for now it's enough simply to observe that we need it to explain observations and, whatever it's made of, it's not made of atoms.

What else might we need?  What about heat?  We observe that things get hot and cold, but the repertoire of atoms doesn't seem to necessarily change with temperature.  A chair can be hot one moment, and the exact same chair made of the exact same atoms can become cold at a later moment.  Maybe the difference between a hot chair a cold one is that a hot chair contains more "hotness" (a.k.a. heat) than the cold one.

It turns out, after a very very long story, that we don't need "hotness" to explain why some thing are hot and others aren't any more than we need "chairness" to explain why some things are chairs and others aren't.  Hotness and coldness, it turns out, are actually just the result of atoms moving in a particular way.  Atoms, it turns out, are always jiggling around with tiny random motions.  The faster they jiggle, the hotter the object.

Note that there is a lot of heavy rhetorical lifting being done by the slogan "the faster they jiggle, the hotter the object."  Hidden underneath these eight words are two entire fields of scientific study: thermodynamics and statistical mechanics.  I don't want to get into those weeds, but it is important to know that the weeds are there.

So besides atoms and light, is there anything else we need to explain our observations?  The answer turns out to be mostly "no".   Why just "mostly"?  Because there are some other things that are required to explain things like nuclear reactors, black holes, the movements of galaxies, and other esoteric phenomena.  But for things that happen here on earth and in our solar system (outside of nuclear reactors and particle accelerators) atoms and light are all you need.  Again, this apparent simplicity is covering up a lot of hidden complexity, but for our purposes we can ignore most of that complexity and just go with the intuition that atoms arranged in some ways make chairs and atoms arranged in different ways make noses and atoms arranged in yet other ways make the moon and the Taj Mahal.

There is a technical term for an arrangement of things.  It's called a state, as in a "state of being".   There is also a technical term for the things that are arranged in a particular state: those are called a system.  So a chair, a nose, the moon, and the Taj Mahal are all systems of atoms, and those systems are in particular states which we label "chair", "nose", "moon" and so on.

The concept of "state" is much more general than that.  The state of a system comprises more than just what category of Thing it belongs to.  It can also include things like that system's location, its state of repair, its temperature.  In the case of something like a folding chair, the state can include whether or not the chair is folded or deployed.  In the case of (say) an electronic device, its state can include things like "broken" vs "in good repair", or "on" vs "off".

Thinking in terms of systems and states is extremely general and powerful.  These concepts allow us to talk about a huge variety of seemingly disparate ideas in a unified manner.  We no longer have to spend mental energy debating whether a folding chair is still a chair when it is folded, or whether a broken chair is a chair.  All of these things -- chairs, folding chairs, broken chairs, non-chairs -- are just systems of atoms in different states.  The ideas if "chairs", "folding chairs", "broken chairs" are just labels that we attach to those states.  The labels themselves have no particular significance, except insofar as they allow us to group together different kinds of systems and states in ways that have significance to us for one purpose or another (for example, if want something to sit on).

The boundaries that constitute a system are also flexible.  If you take a chair and paint it, you are allowed to consider the paint as now being part of the system that you call "the chair".  This kind of flexibility is particularly useful when talking about living things, where atoms are constantly coming and going.  A system where atoms come and go is called an open system, and one where the repertoire of atoms is fixed is called a closed system.  (If absolutely nothing comes and goes then it is an isolated system, an idea which will become very important when we start talking about quantum mechanics.)

It is tempting to equate systems with nouns like "chair" and "desk", and states with adjectives like "folded" or "broken".  But there are many nouns that actually refer to states of systems rather than the systems themselves.  A common example is nouns that refer to activities, like "contest", "golf", or "election."  Some nouns are chimeras that can refer to both systems and states.  "Football", for example, can be a general reference to a particular sport (i.e. a collection of activities, i.e. a state), or it can mean a physical Thing, the kind of ball that is used to play the sport of (American) football.

For modern readers, familiar examples of nouns that refer to states are things having to do with computers: software, data, program, web page, bug, security hole, app.  We think of these things as, well, things, nouns, but when we ask what software is made of we run into trouble because software isn't really made of anything.  Software is not a system, it's a state, specifically, a state of a system we call a computer.  And it's a very specific kind of state of that system: it's a state of that computer's memory.  And it's even more specific than that: software is a state of a computer's memory that can be seen as binary digits, ones and zeros.

What do I mean by "can be seen as"?  Aren't the ones and zeros in computer memory just an objective fact?  The somewhat surprising answer to that question is: no, they are not.  The only objective fact inside a modern computer's memory is the presence or absence of electrons in certain locations.  (I haven't talked about electrons yet.  I'm going to ask you to suspend disbelief and assume that what you were taught about electricity in high school science class is actually true.)  And even that gets a little questionable when we get to quantum mechanics.

At this point you may have noticed that I seem to be doing some pretty frantic hand-waving.  I'm having to explain hedges like "can be seen as" and throwing in new concepts like electrons and their presence or absence at certain locations, and then questioning whether that even makes sense to talk about.  There are two reasons for this.  The first is that the real truth has a lot of complicated details.  There is a reason that it took thousands of really smart people a couple of centuries to figure all this stuff out.  Even today, [climbing this learning curve takes years](https://blog.rongarret.info/2024/04/the-scientific-method-part-4-eating.html).  It is possible to present an easier-to-understand simplified version, which is what I am necessarily doing here.  This is not a graduate-level physics course.  But every now and then I feel honor-bound to peel back the curtain and give you a glimpse of the complicated details so that you will continue to trust me not to mislead you.  After all, my testimony is all I have to offer, so I am going to bend over backwards to preserve its value.

But the more important reason is that the idea of systems and states are not in and of themselves part of any explanation.   What they are instead is a kind of framework for constructing explanations, a sort of Erector Set for scientific theories.  By forcing ourselves to talk in terms of systems and states we impose a self-discipline that frees us from much of the vagueness and ambiguity of the English language.  We no longer have to fret about puzzles like, "What is software made of?"  Software isn't made of anything.  Software is not a system, it is a state of a system.  It's the same with chairs.  Chairs are a system (of atoms) but chairness is a state.  Note that the statement, "Chairness is a state," is an explanation.   It is an explanation that conforms to the constraint that it be couched in terms of systems and states.

Why would we want to tie our hands in this way?  Maybe there are observations that require explanations that cannot (or simply do not) conform, or for which the best explanation is one that just happens not to conform.  That's possible.  But so for, in the four-hundred-year-long history of modern science, no counterexample has ever been successfully demonstrated.  All successful scientific theories to date conform to this constraint, and it's actually not hard to see why: it's because the world happens to be such that it lends itself to being described in terms of things that actually exist in some foundational way (systems) and the behaviors that those things can exhibit (states).  There are technical terms for all this.  The list of things that are considered to make up systems is called the ontology of the theory, and the description of behaviors (i.e. how systems transition between states) is called the dynamics of the theory.  The familiar physics of everyday life, the kind they teach in high school physics classes, and which mostly corresponds with common sense, is called classical mechanics.   The ontology of classical mechanics comprises objects that exist and move around in three-dimensional space (i.e. atoms) and the dynamics are Newton's laws of motion, and Maxwell's laws of electrodynamics.  And if you want to get fancy, you can throw in relativity, both special and general, under the classical umbrella too.

I have to emphasize here again that none of the details actually matter for our purposes.  What matters is that all of what I have just described is entirely uncontroversial.  You don't have to understand any of the details of these scientific theories.  All you have to know is that they exist, and everyone who takes the time to understand them comes to the same understanding of what these theories say.   And this is an observation that itself has an explanation, namely, that these theories correspond, at least approximately, to actual objective truth.  In other words, the Objective Reality Hypothesis is correct.

That's the easy part.  We have in hand scientific theories that explain a lot of our subjective experiences.  Does that mean we're done?  Can these theories explain all of our subjective experience?  Or are there still Problems that remain to be solved?  Yes, of course there are!  One of the many elephants in the room is the fact that we are able to construct scientific theories at all!  In order to get to this point, two things had to be true.  First, the universe had to be such that constructing scientific theories was even possible.  In other words, the Objective Reality Hypothesis, or something like it, had to be true to begin with.  In order to discern the laws by which the universe behaves, it is necessary that the universe actually behaves according to laws, which our universe apparently does.  But why does our universe behave according to laws?  And why does it behave according to the particular laws that seem to apply?  There is no immediately obvious explanation for that.

The second apparent requirement for our discovery of scientific laws is that we have the ability to reason, to invent mathematics and technologies that allow us to build scientific instruments and electronic computers and generally carry out the scientific enterprise.  How did that happen?   Again, there is nothing immediately obvious in the behavior of atom that should lead them to naturally make brains, let alone such uncommonly capable brains as ours.

And then there are all kinds of additional mysteries not directly connected to science, but which are nonetheless part of our subjective experience.  Where does consciousness come from?  Where does our sense of right and wrong come from?  And what is the point of all of this?

I touched on this at the end of the last installment, and I don't want to belabor it. I just mention it here for completeness, and also to reiterate my promise that, despite the fact that this chapter was rather dry and technical, I am going to get to the hard questions and not just sweep them under the rug.  But to do that I had to lay some foundations.  Next time I will start to talk about information, and it is not possible to understand information without first understanding what systems and states are.

--- 

Public Service Announcement for those of you who made it to the end: I am going to be doing another debate with MadeByJimBob on Wednesday, April 29 Thursday, May 7 at 9PM Eastern time.  The topic is going to be "Is belief in God a reasonable position?"  It will be on the same venue as last time, Modern Day Debate.  They haven't posted it yet so I can't give you a link, but as soon as they do I'll update this announcement.  Tune in and watch the sparks fly.

Seeking God in Science part 5: Testimony

At the end of the last installment in this series I made a prediction: you believe that matter is made of atoms.  I am confident in making this prediction despite the fact that I have almost no information about who you are because, as far as I can tell, no one in the modern world denies it.  There are people who profess to believe in all kinds of crazy shit, but I have never heard of anyone alive today who denies that atoms are real.

Given this rather overwhelming consensus, it may surprise you to learn that there was legitimate scientific disagreement about the existence of atoms right up to the start of the 20th century.   At that point there was a lot of circumstantial evidence that atoms were real, mainly in the fact that when elements combined to form compounds they always did so in quantities that were ratios of small integers.  That fact could be explained by the existence of atoms, but it wasn't proof that they were actually real.  Back then there were alternative explanations that seemed to account for all the data just as well.

Today we have pictures of atoms, which would seem to make it a slam-dunk.  But we also have pictures of humans walking on the moon, and yet there is a whole industry of lunar landing denialists.  In fact, there are Artemis-mission denialists now!  So why aren't there atomic denialists?  It is actually not that hard to cook up an argument that atoms aren't real: the alleged "photographs" of atoms aren't actually photographs at all, they are just digital renderings of data from so-called "scanning electron microscopes", which aren't really microscopes at all.  A microscope is an device with lenses that magnify light.  Scanning electron microscopes don't have lenses.  They don't even have the magnetic fields that (allegedly) "focus" beams of (alleged) electrons in so-called "transmission electron microscopes".  So all of these "photographs" of atoms are necessarily heavily processed.  In other words, these pictures are literally photoshopped into existence.  (BTW, this is also true of most "normal" photographs taken using digital cameras.  The vast majority of digital cameras do some kind of processing on the data, even if it is just to compress it to make it smaller.  Apple iPhones in particular do a lot of actual image processing (i.e. "photoshopping") to try to make their pictures look better.

However, you have some first-hand evidence that the photos on your iPhone are not that different from reality because you can compare the photos you take with what you saw with your own eyes at the time.  But with photos of atoms that's not possible.  It is physically impossible to see an individual atom with your eyes, or even with an optical microscope.  The only way to get a "picture" of an atom is through some indirect and very complicated process, so complicated that people actually can earn a living by mastering them.

So how do you justify your belief in atoms?  Seriously, take a moment to stop and think about that before reading further.  I'll wait.

It might help to consider what happened that finally persuaded the scientific community that atoms were real.  That consensus was reached long before (so-called) pictures of atoms became available.  What is it that managed to turn a centuries-long running controversy into a universal consensus over the span of just a few years?

The answer to that question is a fellow named Albert Einstein.  Maybe you have heard of him?  He came up with relativity and E=mc².  He won a Nobel prize too, not for relativity, but rather for his explanation of something called the photoelectric effect, which helped pave the way to quantum mechanics.  And he also, on the side, advanced the definitive proof that atoms exist through a mathematical analysis of something called Brownian motion.  This is a phenomenon named after a Scottish botanist, Robert Brown, who, in 1827, published the first description of it.  Brownian motion is the apparently random motion of small particles suspended in a liquid (typically water) when viewed under a microscope.  It turns out that the minute details of how these particles move are exactly what you would expect if they were being pushed around by moving atoms.

That is what finally convinced the scientific community that atoms exist, but that is almost certainly not what convinced you.   Maybe you were aware of Brownian motion, but almost certainly you have never read Einstein's paper, and even if you have you almost certainly didn't understand it.  I certainly don't, and I have a more training in math and science than most people.

The reason you believe in atoms is almost certainly the same as the reason I believe in atoms, or at least why I started believing in atoms: someone in a position of authority, most likely a middle-school science teacher, told you that matter is made of atoms and you believed it.  But even if you were to become skeptical (or simply curious) and start to dig into the details, everything you find will be indirect: papers, articles, photos taken by other people.  In other words, all of the evidence you have for the existence of atoms takes the form of testimony, something you are told by another human rather than something you directly experience for yourself.

And this is not only true for atoms, but for the vast majority of what you and most people believe.  Do you believe that Bhutan exists?  Unless you have actually been there yourself, the only way you can know about it is through testimony.  Do you believe that the far side of the moon exists?   Black holes?  Texas blind salamanders?  Unless you are a member of some very privileged groups, you have no alternative but to rely at least to some extent on testimony to support these beliefs.

In fact the vast majority of what most people think they know comes from testimony and not direct first-hand experience.  This is not an indictment of testimony.  It's essential.  There is just too much information out there, especially in the modern world, to be able to acquire all of it first hand.  But not all testimony is created equal.  People lie, and people make mistakes.  So how can you tell when someone is telling you the truth, especially in a situation where you can't verify a claim first hand?  When I, or your science teacher, or Richard Feynman, tell you that matter is made of atoms, why should you believe us?

The answer is that the actual existence of atoms is the best explanation of your first-hand subjective experience of having all of these people telling you that they exist, just as the actual existence of chairs is the best explanation for the fact that everyone agrees about chairs.  Consider what would have to be true if atoms did not exist.  How would you explain the fact that there is both a scientific and popular consensus that they do?  How would you explain the periodic table of the elements?  The atomic theory is much, much more than the simple assertion that atoms exist.  It is very specific about exactly how many kinds of atoms there are (92 in nature, a few more that we can create in nuclear reactors) and how they behave.  Moreover, there is no disagreement about any of this.  There is no scientific faction arguing for the existence of different kinds of atoms or an alternative periodic table.  There are not different denominations of physics or chemistry.  There is an absolute consensus about all of these details.  If people are lying or mistaken, they would all have to be lying or mistaken in exactly the same way.  It would have to be either an enormous coincidence or an enormous conspiracy, neither of which is very likely.  So the best explanation of this consensus is that the consensus is actually true.

But it's not just all that.  There is also your first-hand experience of reading these very words.  How do you explain that?  This is a blog post, so you are almost certainly reading it on a computer or a smart phone.  How does that work?  Well, there are these things called semiconductors which are made mainly of silicon atoms.  You can find vast quantities of excruciatingly detailed information about exactly how they work, and all of it will agree.  Again, there are only three possibilities: either all this information has been deliberately produced to deceive you, or it has been produced with good intentions but it is nonetheless wrong (but somehow all of these devices work anyway), or it is right.  By far the most likely explanation is that the information is right, and so atoms exist.

Moreover, this implies that the people who told you that atoms exist are trustworthy sources of information.  It doesn't mean that they are perfect, that they are never wrong, or that they never lie.  But at least in some cases, their testimony actually does align with objective reality and allows you to make correct predictions about the future.  If someone like this tells you something, there is at least the possibility that a good explanation for their testimony is that they actually know something, and are actually making a good faith attempt to impart that knowledge to you.

The existence of atoms is among a handful of explanations that are so well established that they can safely be labeled as scientific facts.  Included among these are relativity theory, thermodynamics, and of course the atomic theory.  The $64,000 question is now: can these "scientific facts" account for all of our observations?  Can they answer all of our questions?  In particular, can they answer the Big Questions:  What is consciousness?  What is love?  Do we have free will?  What is the standard for moral behavior?  What happens after we die?  And perhaps most importantly, why are we here?  What is the point?  Humans are just so damned complicated that it seems a priori impossible that all of our subjective experience could be accounted for in this way, that our entire existence can be reduced merely to "atoms doing their thing."

In the rest of this series I am going to argue that yes, it can, and I am going to explain exactly how.  But that is going to be a long row to hoe.  For now I want to present the argument for the opposing point of view to the best of my ability.  If I am going to claim that my explanation is the best one available, I have to be willing to put it up against the strongest alternatives.  So if you are an advocate for one of these alternative and I get something wrong here, let me know in the comments.

The claim that all of our subjective experiences can be accounted for by the behavior of atoms is not only wrong (this argument goes) it is manifestly absurd, a category error.  Subjective experience is a fundamentally different kind of phenomenon than anything an atom (or large groups of atoms) could possibly produce.  Atoms simply move around according to deterministic laws.  Nowhere in those laws is there anything even vaguely resembling everyday human subjective experiences like consciousness, love, shame, pride, joy, anger, sadness.  Atoms have no moral agency, and cannot acquire moral agency simply by being aggregated into sufficiently large collections.  There is something qualitatively different between human experience and the deterministic behavior of atoms.

Moreover, our very existence cannot be accounted for simply by Atoms Doing Their Thing.  Life is so mind-bogglingly complex that it cannot have been brought about by mere chance and deterministic laws.  Biological evolution can explain some of the characteristics of life, but it cannot explain how life arose in the first place, or how the universe itself arose in the first place.  To explain those it is necessary to hypothesize a Creator (or at least a creator).  Given that, it seems plausible that the reason we are here is that the Creator wanted us to be here, that we exist to fulfill some kind of purpose.  Moreoever, it seems plausible that the Creator has revealed that purpose to some of us, and that the people to whom that revelation has been made wrote it down so they could share it with the rest of us, and that is the reason holy texts exist.  These are not the results of humans making shit up out of whole cloth, they are the instruction manuals for life given to us by the Creator, because we are not expected to just figure it all out on our own.

That's about as far as I can get with steel-manning the religious position in general.  To go any further than that I have to grapple with the fact that there is a huge variety of holy texts on offer, and they don't all agree with each other (to put it mildly).  In fact, even by positing a Creator with a capital C I have already biased myself against certain Eastern traditions like Buddhism, which does not admit (or at least does not emphasize) a Creator, or even a creator.  So I simply don't know how to go further without advancing one religious tradition over another.  I am not a religious scholar.  I know a fair bit about Christianity, a little less about Islam and Judaism, and next to nothing about eastern traditions like Hinduism, Buddhism, Jainism, Shintoism... I don't even know how long a list like that would end up being.

Going forward I am going to focus on western monotheism because of my own cultural biases and because it's what I know.  So I am going to talk about The Creator rather than a creator, which I intend to encompass as much as possible of Western monotheism, and specifically the traditions that grow out of the book of Genesis.  I'm going to focus mainly on Christianity, not because I want to exclude Judaism and Islam, but simply because I've studied the former more than the latter.

I'm going to leave it at that for now.  Next time I will start diving in to the details of how science can at least begin to answer some of the Big Questions.  Here's a teaser: the fact that we cannot definitively rule out the possibility that we are living in the Matrix will turn out to be very significant.

Reflections on dying

My father died last week.  I am now the sole surviving member of my immediate family.  My sister died in 2020 and my mother in 2024.  The experience of dealing with three deaths in the family has been... interesting.  There are things I know now that I wish I'd known then, and things I can reveal now that I could not before.  I'm writing this in the hope that someone reading this may end up better prepared than I was, and may even be able to save someone.  Because my sister died in 2020, everyone assumes it was due to covid, and in a way it was, but covid is not what killed her.  She died from anorexia.  And, as it turns out, it goes all the way back to when she was in junior high school.  I know this from a letter that she wrote back then, which I discovered among my parent's effects after my father died.

The entire time we were living together in my parents' house, and even well after we both left to go to college, I had no clue there was anything wrong.  My sister looked healthy, seemed healthy.  She was enormously popular among her peers.  She was literally the homecoming queen in high school.  Among my parent's effects I found a plaque naming her "friendliest person" in her class.  But even then she was already, ever so slowly, killing herself.

She hid her disease exceptionally well.  Throughout her twenties and thirties she looked extraordinarily healthy.  At one point she got into body-building.  She looked like this:

 

Twenty years later she looked like this:

 

That is a photo of her with my father on a trip to Disney World in 2019.  She was 53 years old.   We didn't know it at the time, but that would be our last time together as a family.  Nine months after that photo was taken the covid lockdown began, and five months after that she would be found dead in her condo.  If the pandemic had not happened it's possible she would have been in the office that day, but instead she was working from home where she lived by herself with her two cats.

I debated with myself for a long time over whether to publish that photograph.  I don't want her to be remembered that way.  I want her to be remembered the way she was in her prime.  But even in her prime she was already sick, and so I decided to show what she looked like at the end in the hopes that others might be able to avoid her fate.  One of the insidious things about anorexia is how slowly it kills.  Irit appeared to be fine for decades.   But she obviously wasn't fine.  By the time it became evident that she wasn't fine, it was probably too late to do anything.  When we saw her in 2019 everyone in the family was shocked.  She had been getting thinner for a very long time, but now she looked like she'd walked out of a Nazi concentration camp.  Moved by her shocking extreme gauntness, everyone in the family tried to talk to her, to tell her that she needed to eat more, but it was far, far too late.  We didn't know it, but she was already walking dead, and had been for a very long time.

My sister's disease was born when she was still a teenager.  And one of its roots is something that I could never publicly reveal while my father was still alive.  I don't think he ever realized this, and if he had, I think it would have destroyed him.  You see, when we were children, my father had a pet name for my sister.  He called her, in Hebrew, "shmeine-bumba" which, roughly translated, means "little chubby one."

Of course, she wasn't.  My sister was never chubby.  But that was the self-image that my father's pet name seared onto her soul.

[Interlude] 

I've been staring at the above paragraph for three days now wondering how to finish this post.  I want this story to somehow be constructive, to be a call to action, but the problem is I'm not sure what kind of action to call for.  My wife correctly predicted that my sister was going to die years before she actually did, and wanted to intervene somehow, but even today I don't know what a successful intervention would or even could have looked like.  The problem is that by the time it was evident from looking at her that she had a problem it was probably already too late.  Many people tried to tell her that she was too thin, but she refused to talk about it.  Short of strapping her to a gurney and force-feeding her, I don't know what could have been done.

Normally my advice in a situation like this would be to consult an expert.  But the irony is that my sister was an expert.   She was a psychology professor.  She had a Ph.D.  She actually worked as a consultant counseling obese people before getting gastric bypass surgery.

So I guess my hope here is just to raise awareness.  Be aware, and be kind.  Don't tease your daughters about being fat.  If you are a young person, don't tease your peers about being fat (especially if they aren't) either on-line or IRL.   You could, quite literally, be killing them.

Slowly.

Very,

very,

slowly.

[UPDATE] My wife pointed me to this article, which is based on this research paper.

This quote from the article really struck me:

Up to one in five people with chronic anorexia may die as a result of their illness, either due to the direct effects of starvation and malnutrition or due to suicide, making it the deadliest of all psychiatric disorders.

 Yep.

Seeking God in Science part 4: Chairness

I concluded the last installment in this series with a deceptively simple claim: Things exist.  This two-word quip is a scientific hypothesis, an explanation for some of my subjective experiences, specifically, my ability to see and touch and hear and small and taste, well, things.  The explanation is that these things that I perceive really do exist in point of actual physical (and possibly metaphysical) fact, i.e. that there is an objective reality that actually exists "out there", independent of my mind.  This is so obviously true, so obviously the correct explanation that there seems at first glance to be no point in discussing it at all.  But as we will see, this hypothesis actually turns out to have some pretty serious problems, and in fact, when we drill down far enough, it will actually turn out to be wrong.

But let's take this one step at a time.

First, let's give this hypothesis a name.  I'm going to call it the Objective Reality hypothesis, or ORH for short.  This hypothesis says that some (though not necessarily all) of my subjective perceptions can be accounted for in a totally straightforward way by the existence of actual physical things.  I can see and touch and hear other people because there actually are other people, and we can all agree that there are chairs and tables and computers because there actually are chairs and tables and computers.

At this point you may be thinking, well duh, of course the reason everyone agrees there are chairs is because there really are chairs.  But it's not so simple.  Consider, for example, rainbows.  People will agree that they see a rainbow just like they agree that they see a chair, but a rainbow is unlike a chair in some fundamental ways.  You can see a rainbow, but you can't touch it.  If you try to get close enough to a rainbow to touch it, the rainbow will disappear.  Rainbows are part of objective reality but they are not physical things.  Rainbows are just water droplets lit up in a very particular way.

Rainbows are not the only things that look like they might be physical objects but actually aren't.  You are probably reading this on a computer screen, which can mimic the visual appearance of just about anything.  Before computer screens there were movies, and before movies there were paintings, and after computer screens there will probably be virtual reality glasses or implants.  As technology improves, it gets harder and harder to distinguish actual physical reality from a simulation.

Aside: a while ago I got a demo of the Apple Vision Pro, which is a virtual reality headset.  While you are wearing it what you are actually looking at is a pair of tiny screens.  But there is also a camera which projects an image of whatever the headset is pointed at onto the screens.  The illusion is so compelling that during the demo I actually forgot that I was looking at a screen and became convinced that the screens were transparent, that I was actually looking through them and directly seeing the room I was in.

Which brings up an interesting question: how can you be sure that the things you perceive as actual physical objects are in fact actual physical objects and not a simulation?  How can you tell the difference between "real" objective reality and a high-quality virtual reality, one that includes all of your sensory modalities?  How can you be sure that reality is actually real and you are not just living in The Matrix?

I'll leave that as an exercise for now and proceed on the assumption that objective reality is actually real, and that part of this objective reality consists of real physical objects like chairs.  I'm going to refer to such objects as Things with a capital T.  Objective reality includes abstract things like words and ideas and sounds, and ephemeral things like rainbows and the images on computer screens.  These are lower-case-t things, but they are not upper-case-T Things.  When I refer to upper-case-T Things I mean actual physical objects made of matter.

One of the distinguishing characteristics of Things is that they exhibit certain regularities in their behavior.  The most important of these is something I call the Law of Location: Things exist in particular places at particular times, and they move between different locations along continuous trajectories.  This is the thing (lower-case t) that allows us to ascribe identity to Things.  We can distinguish (say) this chair over here from that chair over there by virtue of the fact that this chair over here is, well, over here, and that chair over there is over there and not over here.  We can move the chairs so that the chair that used to be over here is now over there, but because the chair had to move in a continuous trajectory we can still meaningfully say that the chair that is now over there (after we moved it) is the same chair as it was before we moved it.

The Law of Location is so deeply ingrained into our psyches that even giving it a name seems like I'm belaboring the obvious, but there is a good reason for it: there are Things — or at least things that appear to be Things — that do not obey the Law of Location.  But again, let's not get ahead of ourselves.

Instead, let's talk more about chairs.  For some reason, chairs are a favorite example among philosophers and religious apologists.  There is a thing in philosophy called the "problem of universals" which asks the question (and I'm just quoting Wikipedia here): "Should the properties an object has in common with other objects, such as color and shape, be considered to exist beyond those objects? And if a property exists separately from objects, what is the nature of that existence?"  In other words, is there such a thing as "chairness", some kind of ineffable chair-like essence which all chairs have in common?  (It sounds a little less silly if you put it in terms of other kinds of properties: is there such a thing as "redness" which all red things have in common?  Is there such a thing as "loudness" which all loud things have in common?)

But this is not about philosophy, this is about science.  Science starts not with abstract philosophical questions but rather with observations, and one of the observations we can make is that chairs are a thing, that is, people talk about chairs and they seem to be able to say coherent things about them.  But what actually is a chair?  When people talk about chairs, what are they actually talking about?

At first glance this seems like a silly question.  Everyone just knows what a chair is.  It's something like this:

But trying to get a handle on exactly what is meant by "something like this" turns out to be not so easy.  What exactly qualifies as "something like this"?  For example, is this a chair?

It is very unlike any of the chairs in the previous picture.  It doesn't have a back.  You can sit on it, but it's a weird kind of sitting where some of your weight is supported by your knees and there is no support for your back.  And what about this?

That is a photograph of a sculpture in Geneva, Switzerland called "Broken Chair".  It looks like a chair.  In fact it looks more like the chairs in the first photo than the one in the second photo does.  It has four legs (notwithstanding that one of them is broken) and a back support.  But you can't really sit on it because it is the size of a multi-story building.  So is it a chair?

And what about this:

This is a (picture of a) Thing that was once a chair, but is it still a chair?  You might actually be able to sit on it, but it only has two legs.  Does a pile of bricks holding up the other side count?  If this is a chair, are the bricks part of the chair?  They are kind of essential to the chair's function, but I think most people would say that they are not part of the chair, that they are merely holding up the chair — if indeed a chair broken to this extent still counts as a chair.

And what about this:

That has four legs and a back and it's the right size, but if you tried to sit on it you would be in for a nasty surprise.

Here is one final example.  This is pretty clearly a chair:

Specifically, it is a folding chair.  It is designed to be folded up so that it occupies less space for storage, like so: 

When a folding chair is in its folded-for-storage configuration, you can't sit on it any more.  So is it still a chair?  Most people would say yes, of course, because all you have to do to be able to sit on it is unfold it.  But the same can be said of broken chairs: all you have to do to a broken chair to be able to sit on it is repair it.  Is there a substantive difference between unfolding a chair and repairing a chair beyond the mere quantity of effort involved?  At what point does the effort required to repair a chair render a chair so broken that it is no longer a chair?

It gets worse.  Suppose we take a broken chair and repair it.  Is it still the same chair as it was before, or is it a different chair?  This question is called the "Ship of Theseus" problem because it was originally posed as a thought experiment about ships rather than chairs, but the puzzle is the same: take any Thing — a ship or a chair or whatever — and start replacing parts of it until at the end there is nothing left of the original.  Is the result the same Thing or a different Thing?

We can make this conundrum even more explicit: Take any Thing that can be disassembled into parts, and a bin of replacement parts.  We can take parts out of the bin and make a new Thing, a copy of the original, but this new Thing is clearly a different Thing because the original still exists.  Now disassemble the new Thing and use the parts to replace parts of the original one by one.  The end of that process is the exact same set of parts that comprised the new Thing that we made before, so this must also be a new Thing.  Indeed, it is the same new Thing as before.  But there is obviously no clear dividing line between when the old Thing became the new Thing.

This lack of sharp dividing lines is fundamental to the nature of Things.  It will become very relevant later when we start talking about the nature of humans and brains and minds and whether or not abortion is murder, but we are getting WAY ahead of ourselves.  For now let's get back to the fundamentals: chairs, and how they relate to the scientific method.  I want to be very explicit about what is going on at this stage in the discussion in those terms.  I am trying to explain some of my subjective experiences.  Specifically, I am trying to explain my gut feeling that the word "chairs" has a meaningful referent in objective reality, i.e. that there really are chairs "out there" in the real world.  The hypothesis under consideration is that chairs are Things, and what distinguishes chairs from non-chairs is some property — chairness — that chairs possess and non-chairs do not.  The hypothesis is that this property is, like the chair itself, part of objective reality, that it's a real thing (though obviously not a real Thing) "out there" in the world.  This position is called essentialism.

Essentialism is problematic for two reasons.  First, it turns out to be really hard to get a handle on exactly what Things are chairs (and thus possess this hypothetical "chairness" property), and second, we can change whether or not a Thing is a chair simply by moving parts of it around.  In fact, we don't even need to move parts of it around.  Imagine carving a chair out of a single (huge) block of wood.  The end result is a chair, and so would have "chairness".  But notice that the only things that moved during the carving process were the parts of the block of wood that were not part of the final chair.  The wood that makes up the chair doesn't move at all.  So where did its final "chairness" come from?  Was it there in the block of wood all along, or was it somehow imbued into the remaining wood during the carving process?

To help answer these questions let us consider a different property: redness, a hypothetical property shared by red things.  We can see that redness is different from chairness merely from the structure of the word.  The word "redness" is built out of an adjective — red — whereas "chairness" is built out of a noun, which is what makes it sound kind of funny.  There is no noun associated with redness, we have to resort to the phrase "red things", which immediately suggests another interesting puzzle: are there any red things that are not red Things?  Does a thing have to be a Thing in order to be red?  Is Santa Claus's coat a Thing?  When a pixel on your computer screen turns red, is it now a red thing?  Is it a red Thing?  The red band in a rainbow pretty clearly has redness, but is it is not a red Thing (because a rainbow is not a Thing).  But is it a red thing?

There is another difference between redness and chairness: chairness (if it actually exists) can be detected using multiple sensory modalities.  Chairs can be seen and touched, so even a blind person can (at least potentially) tell whether something is a chair.  But redness can only be seen -- it cannot be touched or heard or smelled or tasted.  So can a blind person tell if something has redness?  (Yes, they can!  Figuring out how is also left as an exercise, but here is a hint: even normally sighted people cannot see ultraviolet light.  So can normally sighted people tell if something has ultra-violetness?)

But all of this is a distraction.  My subjective perception is that chairs exist and red things exist and other humans exist and (and this is the important part) the vast majority of other humans agree on whether a thing is a chair or whether a thing is red in a huge number of cases.  How do we explain that overwhelming agreement if chairs and red-things — and hence chair-ness and redness — are not real?

Up until about 100 years ago that was still a question open to legitimate philosophical debate, but no more.  The answer is as prosaic (to a modern ear) as it is profound: In the words of Richard Feynman, matter is made of atoms, little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.  All Things are made of atoms.  But unlike chairs, there are bright lines separating different kinds of atoms.  There are exactly 92 different kinds of atoms that occur in nature, plus a few dozen more than we can produce artificially. Then there are a few variations on those basic types called "isotopes" and "ions", but that's it.  Every Thing that you see is made up of some repertoire of those 92 different kinds of atoms.  What we call "chairs" and "tables" and "red things" are nothing more than different arrangements of these 92 different kinds of atoms.

I don't expect you to take my word for this.  I don't even expect you to take Richard Feynman's word for it.  At this point I am advancing this idea in the same spirit as it was advanced in the 19th century when the idea was still controversial: as a hypothesis.  My burden is to convince you that this hypothesis is better than the essentialist hypothesis, that it is a better explanation for what you observe.  And I have to do this without simply saying, "That's what science says" because that would just be begging the question.

That is what I intend to do in the next installment.  But in the meantime I am going to make a prediction: I don't actually have to convince you that matter is made of atoms.  I'm pretty sure you already believe it.  In fact, I'm pretty sure that your belief is so strong that the mere suggestion that this is a hypothesis that is open to question strikes you as absurd.  Of course matter is made of atoms!  Everyone knows that!

If you don't already believe this, if you are an anti-atomist living in the 21st century, please let me know in the comments.  I would really like to learn how you came to question this.

Field report from Maui

Ulua beach, Wailea-Makena, Maui, before the storm: 

and after:

 

We interrupt this post series to bring you an important weather update

Those of you who watched my debate will know that I was in Hawaii at the time.  Well, I'm still here.  I have no idea if this is making news on the mainland, but Hawaii has just gone through two days of one of the most intense Kona storms in many years.  I have never in my life seen rain this hard go on for so long.  The condo that we are in was not designed for this.  There is a large sliding glass door which is wonderful in sunny weather, but the wind-driven rain was hitting it like a fire hose and driving water underneath the door and into the condo.  And it did this for hours and hours and hours, not continuously, but in wave after wave after wave of pouring rain.  At one point I went outside to try to lay down some towels on the outside of the door to be a barrier against the wind-driven rain and I got completely soaking wet in a matter of seconds.  We did our best to hold back the ride (literally!) with all the towels that we had but it wasn't enough and we ended up with about an inch of water inside.  Fortunately, the cavalry eventually arrived in the form of the condo staff with big plastic bags full of clean towels and they got everything cleaned up.  I eventually figured out how to use one of the plastic floor runners as a makeshift dike outside the sliding door to keep the water from coming in, and since then we haven't had water on the floor, though there is water coming in on some of the walls and making the paint blister.  The main road through the nearby town of Kihei has been washed out, as has much of the nearby beach.  100,000 people are without power across the state (happily our power has stayed on).  It's a horrible mess, though the locals seem to be dealing with it courageously.

If you've been wondering why I haven't been blogging these past few days, that's why.  Trying to stop water from infiltrating your shelter gets a wee bit stressful after doing it more or less non stop for two days.  Things seem to be finally quieting down now, and the forecast is for the storm to finally pass overnight so maybe tomorrow I'll get something done.

Debate Post-Mortem

Last Saturday I did my first on-line debate in four years with a YouTuber who goes by the handle MadeByJimBob (who I will refer to simply as JB since JimBob is not actually his real name and MadeByJimBob is just too long).  The topic was "Is Evolution a Reasonable Position?"  The topic was originally going to be "Evolution on Trial" but I pushed back on that for two reasons.  First, that title had the tacit implication that evolution has been accused of a crime, and second, that the actual substance of the debate would be whether or not evolution is true.  I believe it is true, but I'm not a biologist, so I'm not qualified to defend its truth.  The best I can do is defer to the experts.  What I was willing to do was argue for why I think it is reasonable to defer to the experts in this case.

I can save you the trouble of watching the debate by telling you that JB was constantly interrupting me and, hypocritically, petulantly whining whenever I interrupted him in return.  I didn't want the debate to turn into a shouting match, so I just tried to explain that the questions he was asking could not be answered in a six-word sound bite, and if he actually wanted to hear the answers he would have to stop interrupting me while I was trying to give them to him, but it didn't help much.  So there wasn't much substance.  It was mainly JB asking me questions, interrupting me when I tried to answer, and then shaking his head and condescendingly repeating my name over and over and over.  In his world I guess talking over your opponent counts as a win.

There are two things I could have done better.  One was to put more emphasis on the distinction between defending evolution as a reasonable belief and defending it as the truth.  These are not the same.  There are times when it is reasonable to believe things that aren't true.  The best example of this is the belief that gravity is a force that pulls objects towards the surface of the earth.  That is false, but nonetheless reasonable.

The second thing I should have been better prepared for was to explain why my deference to biologists was not an example of the appeal-to-authority fallacy.  Appeal-to-authority can be fallacious, but it is not necessarily so.  Distinguishing fallacious from non-fallacious appeals to authority is a little tricky, but the best way to do it is to go back to the core tenet of the scientific method: find the best explanation that accounts for all of your observations.  In this case, my observations include the uncontested fact that there are over 100,000 biologists in the U.S. alone, and an overwhelming majority (like 99%) of them agree that evolution is true, which is to say, that all of the diversity of life on earth can be accounted for by naturalistic processes, specifically, random variation and natural selection from a single universal common ancestor.  We can also observe that this community produces a lot of useful products, like antibiotics and vaccines, which is best explained by the hypothesis that they have some contact with reality.

Against this we have a community of creationists who insist that life descended from more than one "kind" but who cannot agree on how many different "kinds" there are.  And it's even worse than that.  It's not that there is an actual dispute over what the number is, it's that none of them will even offer a guess as to what the number is.  [UPDATE: turns out that is not true.]  On top of that, this community has never produced anything of value.  Given all that, it's reasonable for an amateur like me to defer to the judgement of biologists.  They may be wrong, but there is quite a bit of evidence that they are closer to the truth than creationists are.

I was taken aback, however, by a critique from another redditor who goes by DarwinZDF42.  [NOTE: I previously said that this person was Dave Farina a.k.a. Professor Dave.  I got this wrong. DarwinZDF42 is actually someone else.  I apologize to Professor Dave.]

Now, I am about to publicly shame DarwinZDF42.  This is something I hardly ever do.  I don't generally think it's constructive to publicly shame individuals.  And I tried to explain to him in the relative privacy of the creation subreddit why he was wrong, but his response was so dismissive and, frankly, obnoxious that I feel this is warranted.  DarwinZDF42 holds himself out as an expert in public, and so I think it is justified to call out his manifest ignorance in public.

The issue at hand is a question I was asked during the Q&A of the debate: what would falsify evolution?  It's a fair question.  One of the classic criteria for a hypothesis to even be considered as a valid scientific explanation is for it to be falsifiable.  The glib answer of "rabbits in the precambrian" refers to an alleged but unconfirmed quote from legendary biologist J.B.S. Haldane as an answer to that question.  Because there is no original source for the quote, there is no way to put it in context, and so we have to make an educated guess as to what it actually means.  And my educated guess is that it means: if we were to find a rabbit in the precambrian era, that would falsify evolution.

That is wrong.  To see that it is wrong, imagine that I went to DarwinZDF42 and told him that I had found a rabbit in the precambrian era.  What do you think his response would be?  Would he immediately concede that evolution has been falsified, or would he be more likely to tell me that I am full of shit, that there is absolutely no way that there could possibly be rabbits in the precambrian, and so I must be wrong?

Now, on this point I would actually agree with DarwinZDF42.  That would be my reaction to someone making this claim.  It is overwhelmingly likely that the person making the claim is lying or has been deceived, and whatever evidence they think they have that there were rabbits in the precambrian almost certainly has a much more prosaic explanation.  But that is irrelevant to the question of whether this would actually falsify evolution.  To answer that question we have to suspend disbelief and consider a counterfactual world where there is actually persuasive evidence of rabbits in the precambrian.  Would that falsify evolution?

No, it would not (though there is a very small caveat which I will get to in a moment).

To understand why, and to understand the "small caveat", I have to start by pointing out that the word "evolution" actually refers to two different (though related) theories.  The first consists of the following general observations:

1.  There are things in nature that make copies of themselves, i.e. replicators exist.

2.  The copies that replicators make are not always perfect.  There is variation.

3.  Some variants of replicators are better at making copies than others.

4.  Which variants are better at making copies depends to some extent on the environment the replicator finds itself in and the variants it has to compete with.

5.  There is a large variety of different environments on earth, and so you naturally get a large variety of replicators.

Those observations lead to a conjecture: that 1-5 are a sufficient explanation to account for all of the variety of life on earth, and that it all descended from a single common ancestor.  No designer is necessary.

Notice that all of this seems plausible even before we look at any actual data.  As framed above, it is a theory that does not require any fossils or trips to the Galapagos.  Democritus could have come up with it.  (In fact, had Democritus actually considered this problem, he may well have even predicted the existence of cells the same way that he predicted the existence of atoms!)

The second thing referred to by "evolution" is a very detailed historical reconstruction of how the current repertoire of life on earth actually arose.  That, of course, is impossible without actual data, and it is bound to be complex, messy, and incomplete, constantly being refined and revised as new data comes in.  Until we have unearthed the last fossil on the planet, this will be a work in progress.

A cornerstone of this historical reconstruction is the so-called Cambrian explosion, a period of very rapid creation of new species.  The Cambrian explosion began about 540 million years ago (MYA) and was followed by the Devonian period (420 MYA) when the first land animals appeared, the Mesozoic (256 MYA) a.k.a. the dinosaur era, and the Paleogene (66 MYA) when the dinosaurs got wiped out and opened the door for mammals to become the dominant land animals.  The earliest known rabbits appeared about 55 MYA.  (And of course all of this is an extreme oversimplification.  There is a reason people make their living studying this stuff.)

So finding a rabbit in the precambrian would certainly be remarkable.  It would be out of place by a few hundred million years, which would surely cause a major upheaval and revision of the currently accepted timeline.  It would probably be the biggest such revision ever.  But would it falsify evolution?  Would it cause the scientific consensus to suddenly accept young-earth creationism?

Almost certainly not.  I can think of many more plausible explanations.  A hoax.  A local event that somehow transported a rabbit fossil into a precambrian geological layer.  A previously unknown geological phenomenon that somehow produced something that looks like a rabbit fossil but actually isn't.  Or even an entirely new and previously unknown period in earth's evolutionary history, the evidence of which is mostly lost to subduction.

Note that that last possibility could plausibly be considered "falsifying evolution" but only in a very narrow sense.  It would falsify part of the current reconstruction of earth's past.  A big part to be sure, but still, only part.  But it would not falsify the central tenet of evolution, that all of life can be accounted for by naturalistic processes proceeding from a single universal common ancestor.  Which is to say, it would (almost certainly) not falsify evolution in the sense intended by the person who asked the question.

So to the question of what would falsify evolution, the glib response "rabbits in the precambrian" is at best just barely defensible, and at worst flat-out wrong (which is one reason to doubt that Haldane ever actually said it, or if he did say it, that he actually meant it, because he was probably smarter than that).  Under no circumstances is it justifiable to berate someone for failing to offer it in response.  That is wrong on so many levels.  Even if rabbits-in-the-precambrian were defensible, there is no excuse for someone who holds themselves out as a science educator to use the condescending and dismissive tone that DarwinZDF42 used with me.  That is never the way to win hearts and minds.  With people like DarwinZDF42 on our side, it's little wonder that the war on misinformation is being lost.