Evolution is a Theory

Evolution is a Theory, not a Fact 

 

The success of current scientific theories is no miracle. It is not even surprising to the scientific (Darwinist) mind. For any scientific theory is born into a life of fierce competition, a jungle red in tooth and claw. Only the successful theories survive—the ones which in fact latched on to the actual regularities in nature. – Bas Van Fraassen , The Scientific Image, p. 40 (1980).

 


On Friday, January 14, 2005, the following “Brief” appeared in the papers across the country: 

Georgia – A federal judge yesterday ordered a suburban Atlanta school system to remove stickers in its high school biology textbooks that call evolution “a theory, not a fact,” saying the disclaimers were an unconstitutional endorsement of religion.  The stickers were put in the books by school officials in Cobb County in 2002.
            “By denigrating evolution, the school board appears to be endorsing the well-known prevailing alternative theory, creationism, or variations thereof, even though the sticker does not specifically reference any alternative theories,”  U.S. District Judge Clarence Cooper said. 

The honorable judge’s logic—that the stickers constitute an endorsement of religion may puzzle many people.  It was based on the impact of the stickers—they were intended to and do in fact promote Genesis literalism in Cobb County schools.  Here is another way in which his ruling makes sense:  Since there is no viable scientific alternative to evolutionary theory, singling out evolution for such a sticker could only be attributed to pressures from the religious right.  If this were not the case, we would have similar stickers throughout the biology book, for example, in the part that described germ theory.  Imagine the infectious disease section being tagged with stickers that said “germ theory is a theory, not a fact.”  Sounds kind of silly, doesn’t it? 

Now for the twist:  Such labels might sound silly, but they would, in fact, be technically accurate.  The word “theory,” as used by scientists, has a very precise meaning–a theory is a system of logic that integrates a set of data points.  Encarta Dictionary defines a scientific theory as  a set of facts, propositions, or principles analyzed in their relation to one another and used, especially in science, to explain phenomena. 

A scientific theory is bound by certain rules. 

1.      It must provide abstract principles that summarize or integrate specific points of data or findings from the real world.
2.      It must follow the rules of logic. Therefore, it cannot be internally contradictory.
3.      It must not be contradicted by empirical findings from the real world, in other words, by facts.
4.      It must make accurate predictions about what will be found in the future, whether by research or by exploration of the world around us. 
5.      It must be testable.  We must be able to engage in inquiry that will either confirm the theory or cause us to modify or abandon it.  
6.      No theory is ever a “fact.”  Over time, though, as the evidence accumulates we may come to the point that finding a better theory seems highly unlikely and a general consensus is reached within the scientific community.  

By these rules, Judge Cooper misspoke in his brief statement.  While discussing the scientific theory of evolution, he referred to “alternative theories,” meaning creationism.   But according to the definition above, creationism is not a theory.  It is a notion, a faith-based intuition, or a belief, perhaps, but not a theory.  Confusion arises from the fact that in every day speech, we use the word “theory” to mean just this, a notion, hunch, or idea.  Here is one non-scientific definition of the word “theory,” also from Encarta:  an idea of or belief about something arrived at through speculation or conjecture.  

Judge Cooper inadvertently played with words.   Alternative theories compete with the theory of evolution only if you pit the two definitions of the word against each other.  In the world of science, evolutionary theory has no viable competitor.  No alternative system of logic and evidence passes the test.  But the judge must be forgiven for blurring two very different kinds of “theories” into one.    Gullible school boards, earnest reporters, and ordinary truth seekers make this mistake all the time.  In fact, they are encouraged to do so by creation propagandists, like those of the Seattle-based Discovery Institute.   

In science, just because something is called a theory doesn’t mean it is on shaky ground.  Since germ theory was first proposed, scientists have accumulated an incontrovertible body of evidence that infectious diseases are caused by microscopic bacteria, viruses, protozoa and fungi.  Likewise, since evolutionary theory was first proposed by scientists, a similar accumulation of evidence has substantiated the mechanisms and processes by which evolution has occurred in the past and is occurring daily.   

Creationists, or, as they prefer to be called these days, defenders of intelligent design—that’s ID to insiders–frequently point out gaps in the fossil record to argue that evolutionary theory is bogus.  See, they say – and they have been saying it for almost a century now – See!  There is a missing link, and another one.  You can’t prove that species evolved from each other.   

They are right, of course.  Some creationists argue that the world was created six thousand years ago with seemingly ancient geological strata and fossils strategically formed and placed during six literal days of creation in order to test our faith.   Whew!  We can’t prove them wrong.    In fact, we can’t prove that the world wasn’t created yesterday, with not only the fossil record but our own memories and everything around us scripted to look and feel like it has a past.  This hypothesis sounds, well, trippy, but both it and the suggestion that the world was created six thousand years ago follow the same path of logic and require the same leaps of faith.  

Again, the focus on absolute proof misunderstands the process of scientific inquiry.   Scientific theories don’t get proven.  They get subjected repeatedly to rigorous tests that could show them wrong, and they either withstand the testing or they fail.  They aren’t proven, but evidence does accumulate, and, oh boy, has it accumulated when it comes to evolutionary theory!  Following the very same rules of logic and sensory input that I have used to write this page and that you have used to access and read it, decades of worth of evidence have piled high.  Take a glance at the stack: 

Geology, paleontology, and the fossil record – For over a century, findings in these fields have been trending – no surprise – in the wrong direction for wishful creationists.   Excavations keep narrowing those gaps in the fossil record.  And narrowing them.  And narrowing them.  In addition, creationists who used to love bashing the vagaries of carbon dating, have gotten no support or consolation from other, more recent methodologies for dating rocks and fossils.   

Naturalistic Observation –  Micro-evolution, meaning small-scale, rapid change has been observed in various species.  One of the earliest examples was a species of moths that evolved a darker coloring as coal burning dirtied their natural habitat and changed the optimum color for camouflage.   On isolated islands, dwarf or giant members of a species may be evident, offering another interesting bit of data linking environmental nuances to change.    

Genetics –  Genetic studies have allowed us to determine when and how biological mutations occur and how changes are passed on.   Remember, natural selection was discovered long before it was understood how information was transmitted from one generation to another.  With the discovery of DNA and genetic mutation, another puzzle piece fell into place.   In recent years, gene mapping has allowed evolutionary biologists to create a more accurate evolutionary tree, using DNA sequences to identify relations among and ancestry of modern plant and animal species.   Some cutting edge research in genetics involves deliberately altering the DNA code to cure genetic disorders, produce disease resistant plants, improve the quality of food products, and so forth.  

Laboratory Research – Biologists are beginning to investigate natural selection under controlled laboratory conditions.  They do this by cultivating rapidly mutating species of bacteria and then subjecting them to environmental pressures.  In one such experiment, a parent strain of bacteria evolved into two strains, one of which lived off of the waste produced by the other.  In the laboratory, population change and equilibrium can be manipulated by changing the host environment. 

Logic –  Natural selection is a very simple concept.  Understood in its most basic form, it can’t not be true.  It says only this:  If you have genetic variation in a population (which we know to be true of terrestrial life forms) and mutations occur (which we know to be true of terrestrial life forms) and you have differential rates of reproductive success (which we know to be true of terrestrial life forms), then the organisms that are most successful in producing offspring will have their characteristics represented in greater numbers in the next generation.  Duh!  Try, for a moment to argue the reverse.  It’s simply nonsense.  When a creationist points to the world around you and says that it couldn’t have happened by chance, tell them they are absolutely right.  It couldn’t.  Only the mutations are “chance.”  From there, the process is ruled by an iron hand, which needs no external transcendence to guide it.  Whether such Transcendence exists is another question; speciation offers no evidence one way or the other.  If your creationist looks doubtful, refer them to The Ancestor’s Tale by Richard Dawkins. 

Mathematics –  Computer programs have been created to model evolutionary change.  Entities that vary, replicate, and have differential reproductive success (all created out of series of binary equations) are allowed to iterate, producing – you got it – population change.  

Natural selective processes explain the spread and change of entities that are nonbiological.  The field of memetics studies mutation and natural selection in the spread of ideas through human populations.  Think about computer viruses, for example.  Social trends, political ideologies, business competition, even the evolution of religions can be modeled by applying the concept of natural selection and survival of the fittest.   

These are facts – observed evidence from the real world.  Evolutionary theory is called a theory because it is a logical structure that accommodates and integrates these facts.  It spells out regularities and principles.  It calls out the common patterns in the changes that occur over time in ideas, cultures and biological species.   It has stood the test of intense scrutiny.  Evolutionary biology is not mere fact, nor is merely conjecture.  It is scientific theory.  

 January 16, 2005     

 

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About Valerie Tarico

Seattle psychologist and writer. Author - Trusting Doubt and Deas and Other Imaginings. Founder - www.WisdomCommons.org.
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