Rant: Creationist Arguments #1
I see the following argument presented quite often in evolution-creationism discussions, but I have trouble articulating a response to it clearly in the heat of debate. So I'll try to lay things out here, and just refer to this.
The argument is: "Evolution is just a theory, and scientists change theories all the time. After all, we used to believe [____]..."
[____] is one of the following:
[The Earth is flat]
[The Sun circles around the Earth]
[We see because light rays shoot out of our eyes, reflect off things and bring vision back to us]
[All matter is composed of the four Elements: Air, Earth, Fire & Water]
[Disease is caused by evil humors]
[etc.]
The unstated conclusion to this argument is "...therefore, because we no longer believe [____], we cannot trust science to stick to a theory, and as a result, we should reject evolution in favor of Creationism/ID."
I will examine the first two, the rest are merely variations.
* * * * *
"We used to believe that the Earth is flat..."
Yep. We did.
At one time, a flat Earth was the accepted scientific explanation. Stand in an empty field, and what do you see? The dome of the sky coming down to touch the Earth in all directions, and (except for minor quibbles, such as local mountains) ... FLAT.
Why don't we anymore?
Basically, the flat Earth theory couldn't explain certain observations that anyone was able to make. I'll mention three:
1. When you look at the moon during a lunar eclipse, you can see that the shadow of the Earth is clearly circular. This observation is the same no matter where you stand on Earth. The only solid object that casts a round shadow in all directions is a sphere.
2. If you stand on a cliff and watch a ship sail away, it will appear to drop into the sea long before it gets too far away to see at all. This cannot be explained by a flat Earth. Falling off the edge would match the flat Earth explanation, but those ships have a pesky way of coming back!
3. Sometime in the 2nd Century BC, Eratosthenes thought about some odd observations. He knew that at the summer solstice (a day fairly easy to identify) the Sun was directly overhead in one city, while in another the Sun was a little south. He could easily measure this by checking the length of the shadow on a sundial.
A flat Earth could explain this if the sun were sufficiently close for parallax to be a factor (parallax is what we use for depth perception; the distance between our eyes means that they have to point in slightly different directions to focus on an object; the subtle differences in angles are used by our brains to figure out how near or far something is.)
The problem with the flat Earth/parallax explanation is that it didn't fit other observations that indicated the Sun was far away. The only other way to get the variation in measurement that Eratosthenes saw would be if the Sun was far enough away (which fit with other observations) so that the Sun's rays were effectively parallel, and for the Earth itself to be curved.
Eratosthenes used his measurements, along with the estimated distance between the cities, to calculate what he thought was the circumference of the Earth. We don't have his calculations available, just his final result, but the general consensus is that he was remarkably close.
These three observations could not be explained by a flat Earth theory, but were explained nicely by a spherical one. One of them has been available since man looked into the sky; another since he had ships able to leave sight of land; the third since a couple centuries before Christ.
So, the answer to the statement "We used to believe that the Earth is flat..." and the question "Why don't we anymore?" is simple.
Science.
The scientific method is a way of looking at the natural world and trying to figure out how it works. Observations are made, data are collected, and theories are developed based on the evidence contained in those observations and data. The old theory didn't fit the evidence, nor could it be modified to do so. So it was thrown out completely and a new theory, one that DID fit the evidence, was accepted.
The round Earth theory has been refined in detail since Eratosthenes more than two millenia ago. We now know the Earth is not exactly a sphere, but is more egg-shaped. But Eratosthenes and his compatriots got the basic premise right, and produced a scientific theory robust enough to withstand the test of time.
* * * * *
"We used to believe the Sun circles around the Earth..."
Yep, we did.
Look around. The sun rises over there, follows an arc across the sky, then disappears over there. Daily, monthly, yearly. At night, the stars also turn across the sky, but the part of the bowl you see changes subtly throughout the year. Then there's the moon, which follows its own complex path in front of the stars; and the planets, which are farther than the moon but closer than the stars.
An easy to understand, simple explanation put everything on a series of nested clear shells. There is one shell for each planet, the sun, the moon, and the stars. Each shell turns independently, accounting for the complex motions of the heavens.
Why don't we anymore?
Well, it turns out the planets are rather ill-behaved. They don't follow straight paths through the sky. They don't even follow nice simple curves. They loop-de-loop and double back on themselves. This made it very difficult for astrologers to cast horoscopes, and they came up with all sorts of complex theories to account for the variant motions.
One of these is "epicycles". In this theory, the planets like Jupiter aren't fixed to their shells. Instead, they're fixed to a secondary shell that rolls around on their primary shell sort of like a glass marble in a crystal bowl. When we see Jupiter going backwards in the sky, it's because we're seeing through the crystal shells to the other side of the marble as it rolls.
But even epicycles didn't cover the finest details.
Then came along Galileo Galilei. He actually looked at Jupiter through a telescope. And what he saw there shocked everyone. He saw a little world, with moons going around it.
Well, if Jupiter could have moons, then Earth couldn't be at the center of everything. Maybe ...
Just maybe ...
The Earth was like Jupiter - just one of a series of worlds circling around the Sun, some with moons, some without.
Suddenly, all those complex epicyclic calculations required by a geocentric universe became much simpler. They didn't go away completely, because Galileo used circular orbits. When Johannes Kelper pointed out that the orbits weren't circles but ellipses, the epicycles got thrown out completely. There were subtle errors in the computed orbits, though.
A scientific theory can be used to make predictions. Newton's calculus allowed him to derive Kepler's equations from his own gravitational laws, reinforcing both as valid explanations for how the planets moved. Finer instruments and the application of orbital mechanics were used to predict the existence of both Neptune and Pluto, because of their small but measurable effect on the orbits of the other planets. But even then, there were still even smaller errors.
Einstein came along and removed the last few errors by noting that energy and mass are equivalent; the vast quantities of energy expended by the Sun need to be treated as mass in the calculations.
So, the answer to the statement "We used to believe the Sun circles the Earth..." and the question "Why don't we anymore?" is simple.
Science.
New tools (Galileo's telescope) provided new observations - ones that could not be made with the naked eye. Those observations and the already existing problems with the existing theory led to a major new theory.
The theory of a sun-centric solar system has been refined in detail since Galileo. Later observations and work by others, including Kepler, Newton and Einstein, led to refinements in the theory. But because the theory of a Sun-centric system got the basic premise right, it was robust enough to handle modification without needing to be discarded entirely.
* * * * *
Both the round Earth and the Sun-centric solar system were fought strenuously at first, and only replaced the earlier paradigms after long years.
Why?
Because they didn't fit the religious beliefs at the time. A round Earth did not fit the literal interpretation of Genesis in the Bible, and a Sun-centric solar system threatened to remove Man from being the center of God's Creation.
* * * * *
We used to believe that the Earth was created in seven days; that God made all the creatures; that He made Man out of clay and breathed life into him; that Noah built an ark to ride out a world-wide flood ...
Yep, we did.
[The "we" in this section refers to those with a Judeo-Christian ancestry. Other groups have different creation stories in their backgrounds.]
The ancient Jews looked around and could see broad groups, or "kinds", of animals - fish, fowl, amphibians, mammals, beasts clean and unclean - and man. They believed that God made everything, and so a story was developed to explain the patterns they saw.
Why don't we anymore?
The literal interpretation of the Biblical creation story does not fit the evidence, no matter how hard the creationists/IDists attempt to twist it. It cannot adequately explain dinosaurs, radiometric dating, sedimentation, fossils, plate tectonics, etc. etc. etc.
Science has developed a theory that does fit the evidence. The evidence is that evolution occurred and is still occurring. The "Theory of Evolution" (ToE) is a scientific attempt to explain the hows and whys of that evolution. Evolution is the fact. The ToE is the theory attempting to explain that fact.
Yes, the ToE has been refined in detail, and continues to be fine-tuned as new evidence, new tools, and new techniques are developed. But Darwin got the basic premise right; it has stood for 150 years.
150 YEARS.
In all that time, with tens of thousands of people examining it, testing it, digging up fossils, trying to find cracks in it - the Theory of Evolution has endured.
It has endured for the same reasons that the round Earth theory, the Sun-centric solar system theory, the theory of gravity, the theory of electromagnetism, valence theory, etc., have all endured. Like all valid scientific theories, they are created to fit the facts, and provide a coherent framework to explain how those facts relate to each other.
So, the answer to the the statement "We used to believe the Earth was created in seven days..." and the question "Why don't we anymore?" is simple.
Science.
The argument is: "Evolution is just a theory, and scientists change theories all the time. After all, we used to believe [____]..."
[____] is one of the following:
[The Earth is flat]
[The Sun circles around the Earth]
[We see because light rays shoot out of our eyes, reflect off things and bring vision back to us]
[All matter is composed of the four Elements: Air, Earth, Fire & Water]
[Disease is caused by evil humors]
[etc.]
The unstated conclusion to this argument is "...therefore, because we no longer believe [____], we cannot trust science to stick to a theory, and as a result, we should reject evolution in favor of Creationism/ID."
I will examine the first two, the rest are merely variations.
* * * * *
"We used to believe that the Earth is flat..."
Yep. We did.
At one time, a flat Earth was the accepted scientific explanation. Stand in an empty field, and what do you see? The dome of the sky coming down to touch the Earth in all directions, and (except for minor quibbles, such as local mountains) ... FLAT.
Why don't we anymore?
Basically, the flat Earth theory couldn't explain certain observations that anyone was able to make. I'll mention three:
1. When you look at the moon during a lunar eclipse, you can see that the shadow of the Earth is clearly circular. This observation is the same no matter where you stand on Earth. The only solid object that casts a round shadow in all directions is a sphere.
2. If you stand on a cliff and watch a ship sail away, it will appear to drop into the sea long before it gets too far away to see at all. This cannot be explained by a flat Earth. Falling off the edge would match the flat Earth explanation, but those ships have a pesky way of coming back!
3. Sometime in the 2nd Century BC, Eratosthenes thought about some odd observations. He knew that at the summer solstice (a day fairly easy to identify) the Sun was directly overhead in one city, while in another the Sun was a little south. He could easily measure this by checking the length of the shadow on a sundial.
A flat Earth could explain this if the sun were sufficiently close for parallax to be a factor (parallax is what we use for depth perception; the distance between our eyes means that they have to point in slightly different directions to focus on an object; the subtle differences in angles are used by our brains to figure out how near or far something is.)
The problem with the flat Earth/parallax explanation is that it didn't fit other observations that indicated the Sun was far away. The only other way to get the variation in measurement that Eratosthenes saw would be if the Sun was far enough away (which fit with other observations) so that the Sun's rays were effectively parallel, and for the Earth itself to be curved.
Eratosthenes used his measurements, along with the estimated distance between the cities, to calculate what he thought was the circumference of the Earth. We don't have his calculations available, just his final result, but the general consensus is that he was remarkably close.
These three observations could not be explained by a flat Earth theory, but were explained nicely by a spherical one. One of them has been available since man looked into the sky; another since he had ships able to leave sight of land; the third since a couple centuries before Christ.
So, the answer to the statement "We used to believe that the Earth is flat..." and the question "Why don't we anymore?" is simple.
Science.
The scientific method is a way of looking at the natural world and trying to figure out how it works. Observations are made, data are collected, and theories are developed based on the evidence contained in those observations and data. The old theory didn't fit the evidence, nor could it be modified to do so. So it was thrown out completely and a new theory, one that DID fit the evidence, was accepted.
The round Earth theory has been refined in detail since Eratosthenes more than two millenia ago. We now know the Earth is not exactly a sphere, but is more egg-shaped. But Eratosthenes and his compatriots got the basic premise right, and produced a scientific theory robust enough to withstand the test of time.
* * * * *
"We used to believe the Sun circles around the Earth..."
Yep, we did.
Look around. The sun rises over there, follows an arc across the sky, then disappears over there. Daily, monthly, yearly. At night, the stars also turn across the sky, but the part of the bowl you see changes subtly throughout the year. Then there's the moon, which follows its own complex path in front of the stars; and the planets, which are farther than the moon but closer than the stars.
An easy to understand, simple explanation put everything on a series of nested clear shells. There is one shell for each planet, the sun, the moon, and the stars. Each shell turns independently, accounting for the complex motions of the heavens.
Why don't we anymore?
Well, it turns out the planets are rather ill-behaved. They don't follow straight paths through the sky. They don't even follow nice simple curves. They loop-de-loop and double back on themselves. This made it very difficult for astrologers to cast horoscopes, and they came up with all sorts of complex theories to account for the variant motions.
One of these is "epicycles". In this theory, the planets like Jupiter aren't fixed to their shells. Instead, they're fixed to a secondary shell that rolls around on their primary shell sort of like a glass marble in a crystal bowl. When we see Jupiter going backwards in the sky, it's because we're seeing through the crystal shells to the other side of the marble as it rolls.
But even epicycles didn't cover the finest details.
Then came along Galileo Galilei. He actually looked at Jupiter through a telescope. And what he saw there shocked everyone. He saw a little world, with moons going around it.
Well, if Jupiter could have moons, then Earth couldn't be at the center of everything. Maybe ...
Just maybe ...
The Earth was like Jupiter - just one of a series of worlds circling around the Sun, some with moons, some without.
Suddenly, all those complex epicyclic calculations required by a geocentric universe became much simpler. They didn't go away completely, because Galileo used circular orbits. When Johannes Kelper pointed out that the orbits weren't circles but ellipses, the epicycles got thrown out completely. There were subtle errors in the computed orbits, though.
A scientific theory can be used to make predictions. Newton's calculus allowed him to derive Kepler's equations from his own gravitational laws, reinforcing both as valid explanations for how the planets moved. Finer instruments and the application of orbital mechanics were used to predict the existence of both Neptune and Pluto, because of their small but measurable effect on the orbits of the other planets. But even then, there were still even smaller errors.
Einstein came along and removed the last few errors by noting that energy and mass are equivalent; the vast quantities of energy expended by the Sun need to be treated as mass in the calculations.
So, the answer to the statement "We used to believe the Sun circles the Earth..." and the question "Why don't we anymore?" is simple.
Science.
New tools (Galileo's telescope) provided new observations - ones that could not be made with the naked eye. Those observations and the already existing problems with the existing theory led to a major new theory.
The theory of a sun-centric solar system has been refined in detail since Galileo. Later observations and work by others, including Kepler, Newton and Einstein, led to refinements in the theory. But because the theory of a Sun-centric system got the basic premise right, it was robust enough to handle modification without needing to be discarded entirely.
* * * * *
Both the round Earth and the Sun-centric solar system were fought strenuously at first, and only replaced the earlier paradigms after long years.
Why?
Because they didn't fit the religious beliefs at the time. A round Earth did not fit the literal interpretation of Genesis in the Bible, and a Sun-centric solar system threatened to remove Man from being the center of God's Creation.
* * * * *
We used to believe that the Earth was created in seven days; that God made all the creatures; that He made Man out of clay and breathed life into him; that Noah built an ark to ride out a world-wide flood ...
Yep, we did.
[The "we" in this section refers to those with a Judeo-Christian ancestry. Other groups have different creation stories in their backgrounds.]
The ancient Jews looked around and could see broad groups, or "kinds", of animals - fish, fowl, amphibians, mammals, beasts clean and unclean - and man. They believed that God made everything, and so a story was developed to explain the patterns they saw.
Why don't we anymore?
The literal interpretation of the Biblical creation story does not fit the evidence, no matter how hard the creationists/IDists attempt to twist it. It cannot adequately explain dinosaurs, radiometric dating, sedimentation, fossils, plate tectonics, etc. etc. etc.
Science has developed a theory that does fit the evidence. The evidence is that evolution occurred and is still occurring. The "Theory of Evolution" (ToE) is a scientific attempt to explain the hows and whys of that evolution. Evolution is the fact. The ToE is the theory attempting to explain that fact.
Yes, the ToE has been refined in detail, and continues to be fine-tuned as new evidence, new tools, and new techniques are developed. But Darwin got the basic premise right; it has stood for 150 years.
150 YEARS.
In all that time, with tens of thousands of people examining it, testing it, digging up fossils, trying to find cracks in it - the Theory of Evolution has endured.
It has endured for the same reasons that the round Earth theory, the Sun-centric solar system theory, the theory of gravity, the theory of electromagnetism, valence theory, etc., have all endured. Like all valid scientific theories, they are created to fit the facts, and provide a coherent framework to explain how those facts relate to each other.
So, the answer to the the statement "We used to believe the Earth was created in seven days..." and the question "Why don't we anymore?" is simple.
Science.