Why Doubting Evolution is Like Doubting Gravity – Part 1

| July 30, 2014

America The Doubtful


Figure 1 – America’s Standing on Accepting the Science of Evolution

America is a world leader in doubting the theory of evolution, perhaps second only to Turkey. For the last 12 years, Gallup polls have shown that somewhere between 40% and 46% of the American adult population believe that humans did not evolve from less-advanced forms of life over millions of years.   In contrast to that, there are probably very few American adults who doubt that the planets in our solar system orbit the Sun, or that Newton’s laws of motion and gravity explain the motion of the planets.  If you examine your own feelings you may find that your level of confidence is not the same for the theory of evolution as it is for Newton and planetary motion. Yet if you ask the scientific community you will find that their confidence in the theory of evolution is as high as their confidence in our theory of planetary motion.

It is tempting to blame this major disconnect between science and the public on any one single factor, but that would surely be an oversimplification.  The sociological, political, and religious reasons for doubting evolution are part of a wider cultural phenomenon that is the subject of many books. They are outside the scope of this article, except for one important factor, which is what I would call the “lay understanding” of how science works. I maintain that anyone who accepts Newton’s explanation of planetary motion as “good science” but rejects the theory of evolution as “bad science” is doing so through a lay understanding of science that does not match what science has done for the last 350 years or so.

The Formalizing of Lay Science

Although some 90% of the world’s Christian population belongs to denominations whose doctrines accept the findings, theories, and methods of modern science, including the theory of evolution, there is a strong fundamentalist strain in American Christianity that has institutionalized a rejection of any theories that conflict with their particular interpretation of scripture. They have put a lot of time, money, and energy into reinforcing a particular naïve lay understanding of science in their congregation to justify a selective rejection of some theories over others while still maintaining the illusion of accepting modern science.  I mention fundamentalists because they have done a good job in articulating the lay public’s understanding of science.

A religious blog site, called Answers In Genesis (AIG), recently published an article called 12 Arguments Evolutionists Should Avoid.  They are telling their congregation that scientists should not use the analogy of doubting gravity in regard to doubting the theory of evolution. I maintain that it is a perfect analogy, because the method by which we develop certainty is the same in both cases.  AIG’s argument:

Argument #4: Doubting evolution is like doubting gravity

Why does this argument fail? We’ll show you. Take a pencil or pen. Hold it in the air. Then drop it to the floor. That’s gravity. Next, make a single-celled organism—like an amoeba—turn into a goat. Go ahead. We’ll wait. . . . No? As you can see, there’s a fundamental difference between operational science, which can be tested through repeatable experimentation, and historical science, which cannot.

Here AIG offers two different phenomena between which they make an important distinction.   The falling pencil is an example of what AIG would call Operational Science and the evolution of a goat from their ancient single-celled ancestor is an example of what AIG would call Historical (or Origins) Science.

They define those two kinds of science as follows:

Operational (Observational) Science: a systematic approach to understanding that uses observable, testable, repeatable, and falsifiable experimentation to understand how nature commonly behaves.

Historical (Origins) Science: interpreting evidence from past events based on a presupposed philosophical point of view.  The past is not directly observable, testable, repeatable, or falsifiable; so interpretations of past events present greater challenges than interpretations involving operational science.

AIG applies their distinctions to the science of evolution on their religious blog site AnswersInGenesis.com in an article called What Is Science?

The past is not directly observable, testable, repeatable, or falsifiable; so interpretations of past events present greater challenges than interpretations involving operational science. Neither creation nor evolution is directly observable, testable, repeatable, or falsifiable. Each is based on certain philosophical assumptions about how the earth began.

Operational Science and Falling Stuff

With the example of gravity, AIG is correct that the way we verify that objects fall to the ground is different from the way we verify that the diverse life on the planet evolved over billions of years from a single common ancestor population.  However, the example given by AIG is not really science at all.  Dropped objects falling to the ground would not be news to anyone alive over the past 10,000 years. Naturally, what we know now about gravity is much more than things falling to the ground, but very little of that has come from what AIG calls Operational Science. That some dropped objects fall to the ground  is really an observation for something so pervasive in life that we would have no reason to look beyond our every day experience and common sense to have confidence in it.   If this is Operational Science, then humans have done Operational Science for hundreds of thousands of years.

Stone Age Falling Science

Imagine going back to some ancient nomadic tribe of hunter-gatherers and consulting with their wisest men. Sitting around a campfire you might say, “Dropped objects fall to the ground.”  The wise men look at you for a while, wondering why you are stating something so obvious, until one of them says, “Dropped birds fly away.”   They all nod knowingly. Then another says, “If you drop a dead bird, it falls to the ground.” More nodding. Another says, “Dropped rocks fall to the ground very quickly.” But then adds, “When leaves become free of the branch, they fall to the ground very slowly.”  More nodding.  Then another, “When we free up the fire in wood, it rises, and so does the smoke.” And another says, “Clouds never fall to the ground.”  And another, “The Sun, Moon, and all the stars in the sky rise slowly from the ground in the East and fall to the ground in the West every day.”

These would all be examples of what AIG is calling Operational Science.   However, the problem is that those observations alone, which can be observed repeatedly, some by experiment, do not give us any more insight into gravity than what our ancestors had tens of thousands of years ago.  In fact,  gravity as we understand it today is not observable through AIG’s Operational Science.  Yes, I meant to say that.  Gravity, as we understand it today, is not directly observable at all, for that matter.   Observing and recording objects falling or rising does not simply show us how gravity works as we understand it today.

You might complain that this is just semantics, because everyone knows that it is gravity that pulls stuff to the ground. And yes, we are quite certain of that at this point in history. In fact, there are few things we are more certain about in nature than that. But it is important to realize that we did not develop that certainty through Operational Science as defined by AIG. How we came to this certainty is important because we are talking about what methods we use in science to come to understand things that were previously unknown to us, such as why do the planets move the way they do, or how did life become so diverse on Earth? It is important to realize that we came to our present understanding of gravity only a few hundred years ago by new techniques of investigation that were only invented a few hundred years ago.

You might also complain that perhaps I am oversimplifying what AIG is calling Operational Science in a way that is unfair. To which I would reply that regardless of how far you want to stretch the definition of what is directly observable, both the Theory of Evolution and Newton’s Law of Universal Gravitation are formulated and confirmed with evidence in exactly the same way. I meant to say that as well. To best understand this we need to appreciate how our understanding of gravity changed over the years in western culture.

Aristotle’s Worldview

Some 350 years before the birth of Christ, the great natural philosopher Aristotle considered the different behaviors of moving and falling objects and offered his own explanation. After the fall of Rome (450 AD) we lost contact with this intellectual property and for most of the middle ages the western world rebuilt its understanding of the universe around some of the fragments of that work that were still available. Around 1100 AD, the western world had recovered much of the Greek writings including Aristotle’s many volumes of writings on nature and the cosmos. The effect of  finding Aristotle’s work on the western world was profound,like a primitive future post-apocalyptic society stumbling upon a still operating Internet connection to Google and the total of western knowledge. For some 2000 years or so up until Newton, our concept of gravity came from the ancient Greeks, specifically from Aristotle.  It took us up until the time of Copernicus for us to start realizing that perhaps the ancient Greeks did not know everything there was to know, as new events and discoveries in the world were obviously in contradiction.

Newton’s Revolution

By the time of  Isaac Newton (born in 1642), the notion of acquiring new knowledge about the universe through actual experimentation was about to have its explosive effects on the rate at which we were to move beyond Aristotle.  Newton was to play a key role in that transformation, in the form of his prodigious work on motion and gravity called The Mathematical Principles of Natural Philosophy or Principia (after its Latin name), published in 1687.  Building on observations from Galileo and Kepler, and driven by his prodigious genius, Newton transformed our understanding of all aspects of motion and gravity, setting the foundation and the basic methodology for the science that followed for the next 300 hundreds of years to the present day. Newton’s work in Principia is a perfect example of how modern science evaluates a new theory for things that are not directly observable, to the point where we might confidently accept it as a better explanation for some aspect of nature.  And it demonstrates how we can develop a high level of confidence that the new theory is a far better explanation than the old one.

Because gravity is something we can all relate to, it is worthwhile to get an appreciation for how we failed to understand it before Newton’s theory, and how Newton would have failed to convince anyone (including himself) if all he relied on was what AIG is calling Operational Science. In the spirit of the Ken Ham – Bill Nye debates on science and creation, let’s see how Newton would fare in promoting his theory if he was relying on AIG’s Operational Science.

 The Great Aristotle-Newton Debate

<The scene is the Royal Society’s large meeting hall in 1685 at a time when Newton is just beginning to formulate his theory of motion and gravity, but is still using Operational Science to prove his ideas.>

Good evening ladies and gentlemen, and welcome to the 10th annual debate on natural philosophy here in the lecture hall of  the Royal Society of London. Our subject for this year’s debate is the phenomena that governs the natural falling and rising of objects, independent of motion imposed upon them from other moving objects. I am Robert Hooke of the Royal Society, and I will be your moderator tonight. I would like to introduce our debaters and thank them for appearing here tonight. On our right is a man who needs no introduction, having established most of the natural philosophy of the western world with his work from 2000 years ago.

<Vigorous applause from the audience>

Thank you very much, Mr. Hooke. It is a pleasure to be here. In fact it is a pleasure to be anywhere in AD 1685.

<Light laughter and vigorous applause.>

And on our left, the young Mr. Isaac Newton, graduate and now Fellow of Trinity College, who has recently been appointed as the second Lucasian Professor of Mathematics at the University of Cambridge.

Thank you Mr. Hooke.  It is my pleasure to be here.

<Light applause>

As background to this debate, let me remind the audience that our understanding of the rising and falling of objects has long been heavily influenced by the hypotheses offered by Mr. Aristotle some 2000 years ago. Mr. Newton has challenged the prevailing theory on falling and rising with a theory he calls the Universal Law of Gravitation. It is our pleasure to have Mr. Newton and Mr. Aristotle here under one roof for the purposes of debating which of their theories might provide us with the best explanation.

Let me begin with an illustration of the phenomena that we are trying to explain. I call everyone’s attention to the way smoke and fire rise upwards, a released quill pen falls to the floor, and how the celestial bodies rise in the east and set in the west like clockwork.  Now, as the saying goes, age before…. um…. as Mr. Aristotle has the benefit of the prevailing theory, I address my first question to him. Mr. Aristotle, can you explain the reason for the disparate motion of all of these things?

Once again, I thank the audience and the Royal Society for offering me a chance to explain and defend my natural philosophy in regard to moving and falling. All objects have a desire to take up their natural place at the center of the universe. The various kinds of objects have different mixtures of air, earth, fire and water, which I offer to you somewhat metaphorically. The element of earth has the greatest density allowing it to take up its natural place with the most vigor, displacing the other elements in the process. And so the spherical Earth we are standing on is the result of material made of earth that has “won the battle”, if you will, over the less dense elements of water, air, and fire as they all attempt to move to their natural place at the center. Water, as the second dense material, can only form a shell around the Earth as it tries to obtain the center. Air, third in density, forms an outer shell, and fire and smoke, last in density, loses out to the other three and is buoyed up to the heavens.

<Loud applause of recognition and agreement>

So in short, you are saying that unaided falling and rising is caused by objects moving to take up their natural place in the universe, some more vigorously than others, according to their density.  They are seeking a goal.

Yes, precisely.

And the Sun and the Moon.  How do they fit into the picture?

The celestial bodies are made out of pure crystalline quintessence, and are not influenced by any laws that govern motion on Earth.

<more applause of recognition>

Thank you so  much for your concise and articulate explanation. Now, Mr. Newton, we are interested in your new hypothesis which I understand is somewhat radical in its departure from what we have come to know through Aristotle. I pose the same question to you, which is how do you explain the underlying causes behind the disparate motion of things that rise and fall?

It will be my pleasure. I, too, would like to thank the audience and the Society for this opportunity. I beg Mr. Aristotle’s forgiveness as I describe my new hypothesis which is often in direct refutation of his.   And in interest of economy, I am going to appeal to that difference without further deference, but meaning no disrespect.

<Aristotle nods afffably>.


Newton’s Law of Universal Gravitation

I submit that the cause for falling motion as offered by Aristotle is nothing more than fancy, if I may render such a harsh judgement on the fruits of such a brilliant mind.  Instead, I offer a counter hypothesis that all objects exhibit a mutual attraction. That is to say that any two objects are attracted to each other. And what causes the pen to fall to the Earth is the mutual attraction between the pen and the Earth. I draw your attention to this drawing I prepared to illustrate the concept.

<the hall is completely silent, contemplating the radical implications>

Mr. Hooke, if he is so inclined, may I inquire to Mr. Newton directly?

<Newton nods his assent, and then so does Mr Hooke.>

Mr. Newton, are we to understand that you have replaced the desire of one object to achieve its natural position, with another desire for two objects to come together?

<Laughter from the audience>

I offer no metaphors for any desire at all.  I propose an experimental philosophy whereby repeated controlled experiments allow us to directly observe the mutual attraction between objects. Hypotheses and assumptions are to be replaced by direct observation. I call this technique Operational (or Observational) Science, where we verify our hypotheses by directly observing the results of experiments.

Brilliant! Have you created a situation for this and measured this mutual attraction? If you can show this repeatedly for many sets of two objects not including the Earth, I would have to concede that my hypothesis would be refuted as I have no explanation for mutual attraction. These two quill pens for example. Might we observe their mutual attraction directly?

No, we cannot observe the mutual attraction of the two quill pens.  This attraction I speak of is proportional to the product of mass of the two objects.  Mass is related to the amount of material, you see. The mass of the pens is too small to generate enough attraction for our sensibilities.  Consider, if you will,  the mutual attraction between the Earth and one pen. The Earth is immense yet you or I can easily lift the pen off the floor and put it back on the podium. Reduce the Earth’s mass to that of this other pen, and you can see why the attraction would be infinitesimal by our sensibilities. The attractive force between two 5 ounce pens would be about  0.0000000000000000000000001 ounce. Even if we were to build an apparatus that could measure such infinitesimal forces, it would be overwhelmed by their mutual attraction to the nearby Earth.

Have you demonstrated this elsewhere with any other two masses that are sufficiently large? Two cannonballs, or two large ships?

No, I don’t believe there are any two masses to be had on Earth that would attract each other sufficiently for our sensibilities.

And you accuse me of being fanciful?

<Audience laughs uncontrollably, Newton looks extremely pale>

<Aristotle looks thoughtful for a moment then turns to Newton>

Mr. Newton. Why is the pen on the floor not drawn to other Earth-sized celestial objects such as the Moon or the planet Jupiter? Surely they are large enough to produce an Earth-sized attraction? If your Operational Science could measure that attraction then my hypothesis would be refuted as it would demonstrate that the center of the Earth is not a unique location in regard to natural motion. But I see no movement of that pen towards the Moon. It just lies there as if it has only one goal, which is to obtain the center of the Earth. As we all examine the behavior of that pen on the floor, we are all witnessing Operational Science, are we not? If so, it seems to be confirming my hypothesis, not yours.

<Laughter from the audience.>

That is an astute observation, Mr. Aristotle, however according to my theory, the mutual attraction diminishes as the objects grow more distant from each other. Furthermore, it diminishes rapidly by the square of the distance. Drawing objects apart by twice their distance causes their mutual attraction to diminish by four, and drawing them to ten times the distance causes it to diminish by 100 and so on. I call this the Inverse Square Law as the effect diminishes inversely as the square of the distance. And so, the mutual attraction between the pen and Jupiter, were it to be Earth-sized and 400 million miles away, would be 0.0000000001 times less than the that of the pen and the Earth. Once again, the effect is infinitesimal to our sensibilities and vastly overwhelmed by our proximity to the Earth.  And so my answer is yes, the pen and Jupiter engage in mutual attraction, but to a degree that is as yet undetectable by Operational Science.

<Audience is moving about getting restless>

Are you truly serious?  Are you proposing to extend your hypothesis to the heavens as well?  Do you mean to say that the celestial bodies behave according to the same laws you claim govern objects here on Earth? And you claim to be able to quantify and predict their mutual attractions with mathematical precision?

Indeed.  That is why I call it the Universal Law of Gravitation. Any and every two objects in the universe exhibit mutual attraction. The Earth and Jupiter, for example.

And yet you have not been able to demonstrate any of what you claim with objects here on Earth.   Will you fly to Jupiter to test whether objects will fall to its surface?   And how will you measure the mutual attraction between Jupiter and Venus?

<Newton looks very pale now, and the audience is making rude noises in his direction.>

<Aristotle looks thoughtful again.  Then his face brightens up as he turns to Newton.>

Mr. Newton, it would seem to me that we might have an opportunity to rescue something from your hypothesis, with all of us present as observers. If your inverse square law is correct, we should be able to move the pen to various heights in the room and observe for ourselves that the pen will get lighter and lighter as its mutual attraction with the Earth rapidly diminishes. Suppose we use a heavy book for this experiment to make the effect more imposing. If we raise a book to ten feet off the floor, your Inverse Square Law would have its mutual attraction be one hundred times less than one foot. This should be easily discernible to even the grossest sensibilities.   Have you ever performed this experiment using Operational Science?

Again, I am impressed by your quick grasp of my hypothesis and how thoroughly you embrace the implications of the new experimental philosophy. However, I neglected to add that when calculating the distance between objects we must use their center of mass, not the distance between their surfaces. We stand here on the surface of the Earth, some 4000 miles  from the its center. Lifting the book ten feet off the floor increases that distance by only 0.000001%, which alters the attraction by an amount that could not be observed by anyone with normal sensibilities.   Even if we carried the book to the top of a five mile high mountain the difference would be still too small to detect, and it would be overwhelmed by the attraction of the mountain itself.

<The audience is now getting very restless with a few tossing balled up programs at Mr. Newton.>

I am sorry gentlemen, but this is all the time we have for the debate itself.

<Audience applauds and many students raise their programs up, indicating they have questions.>

On behalf of the Society and myself, I would like to thank our esteemed debaters Mr. Isaac Newton from our own town of Cambridge, and Mr. Aristotle who has traveled so far to participate in this event. We have time for one question for each for our participants. You sir in the front row.

Questioner 1:
Thank you Mr. Hooke. Mr. Aristotle, were you convinced that Mr. Newton’s hypothesis has any merit?

I have to say that it is a bold and audacious hypothesis, but I am afraid that it is completely immune to verification by the experimental techniques Mr. Newton is proposing.  No, I am not convinced.

One more question, for Mr. Newton.  You there in the colorful cravat.

Questioner 2:
Thank you Mr. Hooke. Mr. Newton, has there ever been an observation using the experimental philosophy of Operational Science that has contradicted the hypothesis offered by Aristotle?

Yes, and this one can be repeated by anyone with results that are unequivocal.  <Aristotle sits up straight and looks at Newton with anticipation.> Drop any two objects of different weight from a high place and contrary to Mr. Aristotle’s hypothesis they will reach the ground at the same time. This experiment will yield the same result repeatedly.

<The audience applauds, already aware of these experiments.>

<Aristotle leaps to his feet in astonishment.>

Mr. Newton, you have managed to shoot a big hole in Aristotle’s hypothesis in this one dramatic case. But permit me to point out that these results are also contrary to yours. As your hypothesis demands a greater mutual attraction between objects of greater mass, the heavier one should reach the ground sooner than the lighter one.

<Newton drops to his chair embarrassed, but nodding knowingly having already figured this out long before the debate>

<Meanwhile the audience erupts into applause and cheers for Mr. Aristotle, moving to the podium, raising Aristotle off his feet and carrying him off in triumphant victory.>

<Newton gathers his notes and leaves quietly out the back entrance to the hall.>

 Why Did Newton Lose the Debate?

Newton lost the debate because nothing about his Universal Gravitation hypothesis was directly observable in the way that Operational Science requires.  There were no techniques for observing mutual attraction or the inverse square law for hundreds of years after Newton published his theory. No experiments were possible that could verify Newton’s UG.  But UG is not unique in this regard. Most of the time in science, when we make our observations to form a hypothesis, we are usually only observing the consequences of a process occurring and not the actual process itself.  If this were not true, we would have figured out most of the universe thousands of years ago, rather than only in the last few hundred years.

For example, magnetic attraction,  sparks from petting cats, light bending as it goes through glass or water, and the heat on our face from very hot objects are all the consequences of same hidden electromagnetic phenomena that includes radio waves.  We don’t actually observe radio waves either, but rather we observe the consequences of the action of radio waves as they act on objects in nature.  The same is true for continental drift, the orbit of planets, atomic and sub-atomic phenomena, and so on.

Why didn’t Newton know this about Operational Science?  Because as we said in the beginning, Operational Science is a recent term invented by a few fundamentalist Christians who needed to justify why they reject the Theory of Evolution but accept the science of gravity.  Newton didn’t use Operational Science because it doesn’t exist.  Also, don’t forget that the debate is fictitious.

That brings up an important question, then.  If we cannot observe the actual hidden causes that we seek to explain with a scientific hypothesis, then how can we test it? Are we just guessing and hoping we get lucky?  Fortunately, no.  We have developed powerful techniques for probing deep into the workings of processes and causes that are hidden from us, and much of the credit goes to Newton who formalized methods for doing this and applied them to the mysteries of gravity and the motion of the celestial bodies.

Newton employed a technique that I will simply call Prediction Science.1 Prediction Science was the key that unlocked the secrets of gravity and the motion of planets and moons, as well as just about every other major scientific discovery of things that remained hidden from us until now.  In Part II I will explain Prediction Science and in Part III we will follow Newton as he probes deep into the hidden causes of planetary motion using Prediction Science. In part IV I will show how Darwin used Newton’s Prediction Science methodology to probe deep into the mysteries of the process behind the diversity of life on planet Earth.



  1. A more formal description is the use of the falsifiable predictions that come from the Hypothetico-Deductive logical form. Prediction Science is easier to remember and highlights the fact that prediction and falsification are the basic principles of hypothesis testing in modern science.

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