Evolution as fact and theory

Evolution is often said to be both theory and fact. This statement, or something similar, is frequently seen in biological literature. The point of this statement is to differentiate the concept of the "fact of evolution", namely the observed changes in populations of organisms over time, from the "theory of evolution", namely the current scientific explanation of how those changes came about.

Evolution, fact and theory

Evolution has often been described as "fact and theory", "fact not theory" and especially by creationists "only a theory, not a fact". Although this is frequently a disagreement over how well the evidence supports each of the various claims made by evolution, the argument has been hampered by terminological confusion. The meanings of the terms "evolution" and "fact" and "theory", as used in the context of this debate, are described below:

Evolution

Evolution is usually defined simply as changes in trait or gene frequency in a population of organisms from one generation to the next. However, "evolution" is often used to include the following additional claims:

1. Differences in trait composition between isolated populations over many generations may result in the origin of new species.
2. All living organisms alive today have descended from a common ancestor.

According to Douglas Futuyma, 'biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest proto-organism to snails, bees, giraffes, and dandelions.'

The term "evolution", especially when referred to as a "theory", is also used more broadly to incorporate processes such as natural selection and genetic drift.

Fact

Fact is often used by scientists to refer to experimental data or objective verifiable observations. "Fact" is also used in a wider sense to mean any hypothesis for which there is overwhelming evidence.

"Fact"
Observation	Established Hypothesis
Facts are empirical data, objective verifiable observations.	'A fact is a proposition affirmed to such a high degree that it would be perverse to withhold one's provisional assent.' Stephen J. Gould. 'A fact is hypothesis that is so firmly supported by evidence that we assume it is true, and act as if it were true.' Douglas Futyuma. 'A fact means something that has been tested or observed so many times that there is no longer a compelling reason to keep testing or looking for examples.' National Academy of Sciences U.S.

Evolution is not a fact because it is not overwhelmingly validated by the evidence and parts of it can be disproven and illogical, as the following exlpains. Half-life dating may prove the exact age of any given fossil (that is found) and can confirm that the planet Earth itself is billions of years old, so half-life dating is a scientific fact and that much of his theory is a fact. Otherwise, we must start by considering the beginning of the issue. According to Darwin’s theory of evolution, life must have evolved from life, which somehow came from matter. But he wasn’t there, so neither he or any so-called scientist can prove this or any part of the theory. This is the main issue; his theory requires much faith and ignorance of any logic or evidence. To believe we evolved from the most basic cells, we must ask and answer what caused the start of this process? A main claim used is that life formed from water in some pond. But in time we can confirm that wasn’t enough, so the claim that lighting may have struck the pond was added. The Darwinian evolutionary process was said to have undergone roughly four billion years. But four billion years ago the Earth must have been in such a blaze that life could have not formed like that. So now when this is brought up the credibility or authority of the person was questioned. Also, cells would require a system of sustaining and reproducing themselves. Matter and random elements can’t result in all this by itself. For so many combinations to create this there needs to be some entity combining or creating. To say that humans ultimately evolved from single cell based life forms is basically saying all life evolved a previous life form, which may have somehow came from matter that was already there anyway. Think about this theoretical explanation; Life evolved from life and matter is always there to create life? It’s strange they claim this to be fact when this can’t be simulated. Surely billions of years of Darwinian evolution can’t be simulated via an experiment to any one person within their lifetime, so faith is required. But still even on a micro level a good Doctor may give patients maybe given many scientific needed things such as Penicillin to kill bad bacteria. But neither natural selection or Darwinian evolution takes place. The bacteria may die, or most of it may die while a minority of bacteria may survive and reproduce. But a new species hasn’t risen. Rather we may end up weeding out the strong by killing the weak. Furthermore, Darwin’s theory rests on the premise that all genetic traits are formed randomly through things such as mutation and recombination. But he simply assumes genetic changes are random because he doesn’t have anywhere near a perfect system to prove how it happens. Darwin himself said, “To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.” Albert Einstein said, “When I read the Bhagavad Gita and reflect about how God created this universe everything else seems so superfluous.” Natural selection may not be random in the sense that it’s survival of the fittest. But to say all species reproduce to the extreme while there are a limited number of resources and survival of the fittest will occur is not very accurate either. To some extent human beings have the ability to regulate population. China is an example of that effort. And humans can also, if responsible, make sure some other species like dogs and cats don’t reproduce to an extreme, irresponsible situation. And remember if farmers didn’t have capitalistic things like subsidiaries, which leads to destroying of crops to maintain high process in a competitive market, they could feed the world many times over. So it’s easy to disprove natural selection. Social Darwinism isn’t even from Darwin but from the work of many other people like Herbert Spencer, Thomas Malthus, and Francis Galton. Darwin himself gave serious doubts to the theory and thought altruistic considerations to be a more suitable evolutionary trait. Also some can argue how Darwinian evolution violates the 2nd law of thermodynamics. Digging for bones can not scientifically ensure we know the chronological order of all species at all times. In India, around the dawn of man it was noted in the Vedas, the wars of the Ramayan, Mahabhart, and other historical sources that people’s bodies are burned after death. This is still done today. So although scientists may find various bones of various species and can scientifically trace them back to specific dates, humans were always around and no so called scientist could disprove it simply by digging for because they can’t be sure to find all bones at all times. They may find different fossils dating back to different times by chance only. Evolutionist T.L. Moor admitted, "The more one studies paleontology, the more certain one becomes that evolution is based on faith alone." John T, Bonner said, “We (evolutionists) have been telling our students for years not to accept any statement on its face value but to examine the evidence, and, therefore, it is rather a shock to discover that we have failed to follow our own sound advice." Darwinists also claim that we evolved from monkeys, yet monkeys are still here. They may argue that we share a common ancestor with monkeys, so that can allow for the theory to support the present existence of monkeys. They may even add that evolutionary process happens over so much large periods of time that these changes can and did happen. However, when you ask for the proof of it, such as the transitional fossils, something odd will happen. You may notice the fossil record is not as complete as they say it is. Other than proving men lived in caves with cave man fossils, they can’t really prove at the present moment that species come, change, and go. Eventually Darwin stated, "I have asked myself whether I may not have devoted my life to a fantasy." "I...am ready to cry with vexation at my blindness and presumption."

The following quotation from H. J. Muller, "One Hundred Years Without Darwin Are Enough" explains the point.

There is no sharp line between speculation, hypothesis, theory, principle, and fact, but only a difference along a sliding scale, in the degree of probability of the idea. When we say a thing is a fact, then, we only mean that its probability is an extremely high one: so high that we are not bothered by doubt about it and are ready to act accordingly. Now in this use of the term fact, the only proper one, evolution is a fact.

The National Academy of Science (U.S.) makes a similar point:

Scientists most often use the word "fact" to describe an observation. But scientists can also use fact to mean something that has been tested or observed so many times that there is no longer a compelling reason to keep testing or looking for examples. The occurrence of evolution in this sense is fact. Scientists no longer question whether descent with modification occurred because the evidence is so strong.

Philosophers of science argue that we do not know anything with absolute certainty: even direct observations may be "theory laden" and depend on assumptions about our senses and the measuring instruments used. In this sense all facts are provisional.

Theory

"Theory"
A scientific theory is a well supported body of interconnected statements that explains observations and can be used to make testable predictions.

Scientific theories describe the coherent framework into which observable data fit. Predictions can be made and tested based on this theory. There have been many theories that attempt to explain the fact of gravity. That is, scientists ask what is gravity, and what causes it. They develop a model to explain gravity, a theory of gravity. Many explanations of gravity that qualify as a Theory of Gravity have been proposed over the centuries: Aristotle's, Galileo's, Newton's, and now Einstein's.

The scientific definition of the word "theory" is different from the colloquial sense of the word. Colloquially, "theory" can mean a conjecture, an opinion, or a speculation that does not have to be based on facts or make testable predictions. In science, the meaning of theory is more rigorous: a theory must be based on observed facts and make testable predictions.

In science, a current theory is a theory that has no equally acceptable alternative theory, and has survived attempts at falsification. That is, there have been no observations made which contradict it to this point and, indeed, every observation ever made either supports the current theory or at least does not falsify it. A revision of the current theory, or the generation of a new theory is necessary if new observations contradict the current theory, as the current findings are in need of a new explanation (see scientific revolution or paradigm shift). However, the falsification of a theory does not falsify the facts on which the theory is based.

Confusion of the terms can arise when we use a single word to describe both the observed facts and the theory that explains it. The word ‘’gravity’’ can be used to refer to the observed facts (i.e., the observed attraction of masses) and the theory used to explain it (gravity is the reason why masses attract each other). Thus, gravity is both a "theory" and a "fact."

Evolution compared with gravity

The terms "fact" and "theory" can be applied to evolution, just as they are to gravity. Misuse and misunderstanding of how those terms are applied to evolution have been used to construct arguments disputing the validity of evolution.

In the study of biological species, the facts include fossils and measurements of these fossils. The location of a fossil is an example of a fact (using the scientific meaning of the word fact). In species that rapidly reproduce, for example fruit flies, the process of evolutionary change has been observed in the laboratory. The observation of fruit fly populations changing character is also an example of a fact. So evolution is a fact just as the observations of gravity are a fact.

In biology, there have been many attempts to explain these observations over the years. Lamarckism, Transmutationism and Orthogenesis were all non-Darwinian theories that attempted to explain the observations of species and fossils and other evidence. However, the Theory of Evolution is the explanation for all relevant observations regarding the development of life, based on a model that explains all the available data and observations. Thus, evolution is not only a fact but also a theory, just as gravity is both a fact and a theory.

Gravity	Evolution
Things falling is an observation of the pull of bodies towards each other.	Fruit flies changing generation to generation is an observation of generational organism change.
Bodies pulling towards each other is called gravity.	Organisms changing generation to generation is called evolution.
Gravity is a fact.	Evolution is a fact.
An explanation for the facts of gravity.	An explanation for the facts of evolution.
Aristotle and Galileo created explanations of the fact of gravity. These are now obsolete explanations.	Lamarckism, Transmutationism and Orthogenesis were created as explanations of the fact of evolution. These are now discredited explanations.
Newton's explanation of gravity is approximately correct but required refinement.	Darwin's explanation of evolution is approximately correct, but required refinement.
Einstein's explanation is a refinement of Newton's explanation of gravity. Einstein's explanation is currently the most accepted explanation of the fact of gravity.	The modern evolutionary synthesis is a refinement of Darwin's explanation of evolution, which did not include genes in its explanation. This modern synthesis is currently the most accepted explanation of the fact of evolution.
Einstein's explanation of the fact of gravity is called The General theory of relativity.	The explanation of the fact of evolution provided by the modern synthesis is the latest and most widely accepted Theory of Evolution.
Gravity is a fact and a theory.	Evolution is a fact and a theory.

Evolution as theory and fact in the literature

The confusion between "fact" and "theory" and the use of the word "evolution" is largely due to some authors using evolution only to refer to the changes that occur within species over generations, while others use the term more generally to include common ancestry and the mechanisms driving the change. However, among biologists at least, there seems to be consensus that evolution is a fact:

• American zoologist and paleontologist George Simpson stated that 'Darwin...finally and definitely established evolution as a fact.'
• H. J. Muller has written, 'If you like, then, I will grant you that in an absolute sense evolution is not a fact, or rather, that it is no more a fact than that you are hearing or reading these words.'
• Kenneth R. Miller writes, 'evolution is as much a fact as anything we know in science.'
• Ernst Mayr has observed 'The basic theory of evolution has been confirmed so completely that most modern biologists consider evolution simply a fact. How else except by the word evolution can we designate the sequence of faunas and floras in precisely dated geological strata? And evolutionary change is also simply a fact owing to the changes in the content of gene pools from generation to generation '.

Evolution as fact and theory

Commonly "fact" is used to refer to the observable changes in organisms' traits over generations while the word "theory" is reserved for the mechanisms that cause these changes:

• Paleontologist Stephen Jay Gould writes, 'Evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts do not go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's, but apples did not suspend themselves in mid-air, pending the outcome. And humans evolved from ape-like ancestors whether they did so by Darwin's proposed mechanism or by some other yet to be discovered.'
• Similarly, biologist Richard Lenski says 'Scientific understanding requires both facts and theories that can explain those facts in a coherent manner. Evolution, in this context, is both a fact and a theory. It is an incontrovertible fact that organisms have changed, or evolved, during the history of life on Earth. And biologists have identified and investigated mechanisms that can explain the major patterns of change.'

Evolution as fact not theory

Other commentators, focusing on the changes in species over generations and in some cases common ancestry have stressed that evolution is a fact to emphasize the weight of supporting evidence while denying it is helpful to use the term "theory":

• R. C. Lewontin wrote, 'It is time for students of the evolutionary process, especially those who have been misquoted and used by the creationists, to state clearly that evolution is a fact, not theory.'
• Douglas Futuyma writes in his Evolutionary Biology book 'The statement that organisms have descended with modifications from common ancestors--the historical reality of evolution--is not a theory. It is a fact, as fully as the fact of the earth's revolution about the sun.'
• Richard Dawkins says, 'One thing all real scientists agree upon is the fact of evolution itself. It is a fact that we are cousins of gorillas, kangaroos, starfish, and bacteria. Evolution is as much a fact as the heat of the sun. It is not a theory, and for pity’s sake, let’s stop confusing the philosophically naive by calling it so. Evolution is a fact.'
• Neil Campbell wrote in his 1990 biology textbook, 'Today, nearly all biologists acknowledge that evolution is a fact. The term theory is no longer appropriate except when referring to the various models that attempt to explain how life evolves... it is important to understand that the current questions about how life evolves in no way implies any disagreement over the fact of evolution.'

Objections to the fact of evolution

Nonetheless, there are those that refuse to accept evolution as fact. House Bill HB1504, in the Oklahoma state legislature, provides a requirement for an "evolution disclaimer" in state-approved textbooks stating that evolution is a "controversial theory" and that "any statement about life’s origins should be considered as theory, not fact.". The creationist website Answers in Genesis claims that evolution should not be classed as a "theory" in the proper scientific sense; rather, they claim that "it would be better to say that particles-to-people evolution is an unsubstantiated hypothesis or conjecture."

The issue was brought before the courts In 1986, when an amicus curiae brief asking the US Supreme Court to reject a Louisiana state law requiring the teaching of creationism in the case Edwards v. Aguillard was signed by 72 US Nobel Prize winners, 17 state academies of science and 7 other scientific societies. The brief provides a detailed argument which it summarises in the following statement.

The Act's unconstitutional purpose is also evident in its requirement that both "creation-science" and "evolution-science" be taught as "theory" and not as "proven scientific fact." To a scientist or a science educator, the distinction between scientific theories and scientific facts is well understood. A "fact" is a property of a natural phenomenon. A "theory" is a naturalistic explanation for a body of facts. That distinction permeates all fields of scientific endeavor. It is no more relevant to discussions of the origin of the universe and life than to any other area of research. By singling out one topic in science – "origins" – for special treatment, the legislature conveys the false message that the prevailing theory of "origins" – evolutionary theory – is less robust and reliable than all other scientific concepts. This misleadingly disparaging treatment of evolution confirms that the Act favors a particular religious belief.

Predictive power

A central tenet in science is that a scientific theory is supposed to have predictive power, and verification of predictions are seen as an important and necessary support for the theory. The theory of evolution did provide such predictions. Two examples are:

• Genetic information must be transmitted in a molecular way that will be almost exact but permit slight changes. Since this prediction was made, biologists have discovered the existence of DNA, which has a mutation rate of roughly 10⁻⁹ per nucleotide per cell division; this provides just such a mechanism.

• Some DNA sequences are shared by very different organisms. It has been predicted by the theory of evolution that the differences in such DNA sequences between two organisms should roughly resemble both the biological difference between them according to their anatomy and the time that had passed since these two organisms have separated in the course of evolution, as seen in fossil evidence. The rate of accumulating such changes should be low for some sequences, which code for critical RNA or proteins, and high for others - that code for less critical RNA or proteins; but for every specific sequence, the rate of change should be roughly constant through evolution. These results have been experimentally confirmed. Two examples are DNA sequences coding for rRNA which is highly conserved, and DNA sequences coding for fibrinopeptides (amino acid chains which are discarded during the formation of fibrin), which are highly non-conserved.

Related concepts and terminology

• Speculative or conjectural explanations are called hypotheses. Well-tested explanations are called theories.

• "Theories" are not "true" in science, at least in the regular sense of the word "true". "True" "theories" only are "confirmed to such a degree that it would be perverse to withhold provisional assent."

• "Proof" of a theory does not exist in science. Proof only exists in mathematics. Experimental observation of the predictions made by a hypothesis or theory is called validation.

• A scientific law is a concept related to a scientific theory. Very well-established "theories" that rely on a simple principle are often called scientific "laws". For example, it is common to encounter reference to "the law of gravity", "the law of natural selection", or the "laws of evolution."

See also

• Theory vs. Fact (in Creation-evolution controversy)
• Evolution is just a theory, not a fact (in objections to evolution)
• Misconceptions about evolution (in List of misconceptions)
• Evidence of common descent
• Epistemology

References

• J.P. Franck, et al., "Evolution of a satellite DNA family in tilapia." Annual Meeting Canadian Federation of Biological Societies. Halifax, (1990).
• M. Losseau-Hoebeke, "The biology of four haplochromine species of Lake Kivu (Zaire) with evolutionary implications." Thesis, Dept Ichthyology, Rhodes University, Grahamstown, (1992).

External links

• Not Just a Theory Discredits the assertion that evolution is "just a theory", with an explanation of the meaning of the word 'theory' in a scientific context.
• Parody website satirizing theory and fact statements
• Talk Origins Response to the claim that no examples of speciation have been observed.
• Glenn Branch (2008-06-06). ""Theory" in Theory and Practice" (pdf). Evo Edu Outreach (2008) 1:287–289. Springer Science + Business Media. Retrieved 2008-07-21. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)