Fact v. Theory in Modern Biology

An interesting discussion occurred in the comments to my recent post on home schooling textbooks. As this question frequently occurs in discussions of evolution, I think it worthy of its own post. Besides, I love this sort of thing.

Commenter Human Ape said this:

Evolution is a basic scientific fact.

That led to the larger discussion of evolutionary theory and its status in science

Stan Gibilisco wrote this:

I accept that according to the evidence, the scientific method leads us to conclude that evolution is by far the most reasonable theory concerning life on this planet, and it explains better than any other theory how we humans got here.

I argue that such terms as truth and fact are appropriate to the courtroom but not the laboratory. In the former venue, I want to know if a witness is telling the truth and if the defendant in fact committed the crime. Science, by contrast, is concerned with data, hypothesis, experiment, and theory, all of which are in principle subject to revision. It's not that scientists are uninterested in the truth; it's that a good theory, based on data, confirmed by experiment and research, and generating further research programs, is as close to the truth as any science can get.

I also supported Stan in his statement about evolution, and in particular about speciation (the idea that new species emerge out of older ones in the history of living organisms).

My SDP colleague, Miranda, wrote this reply to me in the most recent comment:

You suggest that there is as much proof for speciation as anything in biology. I disagree. Some biological theories are easy to prove or disprove. We can, for instance, theorize that children tend to grow taller than their parents. Then we can measure parents and children over the course of time to arrive at a solid answer. Theories that can be tested with measurements and direct observation are, I think, easier to prove than theories about man's relation to slime molds.

I return here to the distinction between the common sense etiology (explanation by causation) appropriate to the courtroom and scientific etiology. In the context of the former, Miranda is surely right. It's relatively easy to determine whether children do or do not tend to grow taller than their parents.

But gathering such information would be only the first step in science. The scientist wants to develop hypotheses concerning the laws or causes that operate in this case, test the hypotheses, and integrate them into general theory.

From the viewpoint of science, I would argue that it is precisely the opposite of what Miranda says. The theory of evolution by common descent, including the concept of speciation, is much better established than any science concerning the heritability of stature.

It is generally assumed that the height of individuals is influenced both by heritable factors like genes and by environmental factors like nutrition. It's notoriously difficult to tease these influences apart. Suppose someone advanced this thesis: the influence of biologically inherited factors on height is negligible; rather, height is, say, 98% a function of environmental factors. Such a thesis would look very unlikely, but it is not out of the realm of possibility. If confirmed, it would please sociologists but it would require no great revision in genetics or other fields of biology, nor would it require any scientifically unusual assumptions.

Now suppose someone advances this thesis: speciation never happens. This would require a rejection or at least a traumatic reinterpretation of the basic history and classification of the species in modern biology. Worse still, one would have to assume either that every existing species has been present since the beginning of life on earth or that new species spontaneously come into being out of nothing. In either case, morphological similarities would have to be interpreted as very odd coincidences or perhaps a lazy imagination on the part of the Creator. In the former case, since many species are highly dependent on specialized ecological niches, one would have to revise the entire science of geology as well.

I reassert my statement that speciation in particular (and evolution from a common ancestor in general) is about as well established as anything in modern biology. However, in so asserting it, I note that Miranda and Stan and I are in agreement regarding the political question. Darwinian evolution ought to be part of the curriculum of a public high school. Home schoolers have to meet certain standards, and perhaps those standards should include an understanding of what evolutionary theory says. But parents should never be required to tell their children that evolution is true.

The distinction between theory and fact has nothing to do with greater certainty on the one side than the other. It is all about different approaches to the matter at hand in different contexts.

Comments

[Miranda Flint]

"Worse still, one would have to assume either that every existing species has been present since the beginning of life on earth or that new species spontaneously come into being out of nothing. "

I'm not sure that this is any more outrageous than believing that life spontaneously came to being out of nothing to begin with. Ultimately, we have to believe that _something_ was either here all along, that it sprang into life spontaneously out of nothing, or that a creator created it. I believe in the last option.

Now my point is not that speciation could not have or has not occurred. I merely think that it is unproven. But maybe the study of biology is based more on theory than I would have guessed.

It would, indeed, be hard to prove that speciation has not occurred, but proving a negative is notoriously hard to do. It would be just as difficult to prove that no species had sprung out of nothing.

Nevertheless, I will concede that speciation looks a lot more likely than I previously thought and that heritability of stature, as you put it, looks more difficult to prove that I would have suspected.

I am still not willing to concede that we came from slime molds. Or anything related to a Bonobo.

[caheidelberger]

Miranda, Dr. Blanchard and all of science appear ready to concede that speciation is not only unproven but unprovable, at least in one sense of the word "proof". But we misuse the word "proof" and do science a disservice when we turn to children and say, "Speciation and evolution are unproven, so don't believe them!"

You retain the liberty to reject the connection between you and the bonobo. You retain the liberty to explain the existence of all life on earth as a product of the mind of God (or maybe one remarkable quantum fluctuation -- not much difference, and perhaps coherent under physics). But your desire for an alternate explanation does not negate the fact (Dr. B., check whether I apply "fact" correctly here) that evolution is the best explanation yet produced by centuries of scientific effort.

[caheidelberger]

(By the way, Miranda, you might be interested in what my friend David Bergan says on the topic. He was a passionate advocate of Intelligent Design. He now appears to acknowledge speciation and natural selection as the more logical explanation... although he still has issues with that first cell self-organizing.)

http://madvilletimes.blogspot.com/2010/03/no-apologia-home-school-curricula-rich.html?showComment=1268253168021#c5677236476787460414

[Ron]

Of course speciation exists. The evidence for it is all around us. Natural selection results in speciation, as does selective breeding.

I submit that selective breeding is an adequate picture of how speciation works.

In 'theory', any two animals of the same genus have the capability to interbreed and thus produce a new 'species'. The crossing of two species results in a sub-species, and so on. Some folks thus make the distinction between micro- and macro- evolution. Speciation - whether through natural selection or selective breeding - is in the realm of microevolution.

Most creationists are not objecting to the idea of speciation if we are talking about natural selection and microevolution, but they refuse the idea that animals can, over time, 'evolve' into new kinds of animals.

Now the word 'kind' as used here is a loaded, biblical word, but can be understood as the word 'genus', since 'genus' is latin for 'kind' after all.

Taxonomy, the classification of organisms into 'species' 'genus' "family' 'order' etc isn't the exact science that one might think it is, but it does do a pretty good job of predicting which organisms have the ability to interbreed. The hybridizing and cross-breeding done by farmers, ranchers, hybridizers, and researchers over the years is based on this principle: that living things sharing the same genus (or of the same kind) can be crossed. An example is the American Bison and Angus cattle; two very different looking animals that readily cross to produce 'Beefalo'.

But can it go further than that? Can natural selection actually produce new orders, families, etc? For the most part, life cycle for most organisms are too long for scientists to directly test this idea. For instance, selectively breeding rhinos into horses over time is a preposterous idea even for an evolutionist, but perhaps there are organisms whose life cycles are short enough that, through many many generations, this idea could be explored. Fruit flies might fit the bill.

Indeed, many millions of fruit fly generations have been selectively bred, resulting in some really strange looking fruit flies, none of which could hope to survive outside a lab, but none of these experiments has ever produced anything but fruit flies. 'Speciation' has occurred, if one wishes to use the word; a sort of microevolution through selective breeding; but no new organisms have been created. In fact, there is zero lab evidence for macroevolution.

I submit that natural selection is the obvious and reasonable experimental picture to test the theory of evolution, but without evidence the 'theory' fails to rise past the level of tantalizing hypothesis.

[Miranda Flint]

Cory: I think you're turning this debate around a little bit. I am not arguing that speciation ought to be taken out of textbooks or that schools should not talk about it. What I am arguing against is Human Ape's statement that parents who chose not to teach the theory should be charged with child abuse. As it is a theory, I have no problem with it being offered as such. I think it would be nice if it were presented as a theory and students were able to look at the evidence supporting it. The problem I have is that theories are often presented as fact - which leads to attitudes like Human Ape's.

I will certainly have a look at the Bergan post.

[caheidelberger]

I'll agree that Human Ape's "child abuse" rhetoric goes too far. Parents teaching I.D. or other faux science are no more guilty of child abuse than parents who encourage their kids to try winning basketball scholarships instead of joining the debate team. Bad choice, but not abuse.

Still, Miranda, your language makes me uneasy. "presented as a theory" -- be careful with that phrase. Too often, people misuse "theory" as code for "unproven bunk". I'll be happy to teach evolution as a theory the same way I teach gravity as a theory: the best explanation available, supported by an overwhelming amount of evidence.

[KB]

Wow! What fun. I am grateful to Miranda for advancing the conversation. But around here, no good deed goes unpunished. So:

1) it is easier to believe that the face some people claim to see in the moon is a sheer accident than to believe that the Mona Lisa is a sheer accident. For the same reason, believing that some Ur organism came into being through natural processes and without the direct influence of divine intelligence is easier to believe than that human beings and giraffes came spontaneously into being, and that all other species did the same.

2) Prions cause mad cow disease. They spread from animal to animal just as bacteria do. But prions aren't alive in any sense, nor do they show any evidence of design. They are merely badly folded proteins, identical to health proteins except for their shape. But when the bad one encounters the good one, it corrupts the good one (metaphorically speaking). I can believe that inorganic molecules can begin to behave like living organisms because they demonstrably do so. Considering viruses, I see nothing implausible about a continuum from the inorganic world to my beagle.

3) Miranda says: "Ultimately, we have to believe that _something_ was either here all along, that it sprang into life spontaneously out of nothing, or that a creator created it." I don't understand the "or" here. Lots of things happen spontaneously. Lightning strikes. Cancer. Or does the Creator intentionally cause each and every one of these things? At any rate, the emergence of life from inorganic matter need be no more nor less spontaneous than that.

More, later, I hope.

[Lynn]

I happen to believe in both creationism and evolution. I believe that God created life, and that based on scientific evidence he did it thru evolution. These are not necessarily two different entities. They can exist together.

[William]

I second Lynn's position. I believe ID & Evolution are not necessarily mutually exclusive.

[Miranda Flint]

Ron:

Thank you for your post, I found it entirely interesting. Have there been any experiments like the one with the fruit-flies that have had more success?

Cory:

I understand why my language bothers you. But there is something troubling also about treating theories, even those with a decent amount of backing as unquestionable facts. Human Ape is not the only person who has suggested that those who refuse to teach or believe in certain scientific theories ought to suffer. Others have suggested that those who refuse to believe in global warming ought to be punished, as progressive types have been doing all the work to save the earth and non-progressives have not. I dislike this idea of punishment for disagreement.

My kids will go to public school. They will learn about speciation and evolution. I have no problem with this at all. I would like them to understand the theories and I would like them to know how much evidence supports them. But I would also like them to be free to look at other explanations. Maybe right now these theories are the best we have. But maybe, as we speak, someone is coming up with a more plausible answer. I don't know. But I do know that if someone is talking about bringing someone to court on charges of abuse that I want them to have courtroom proof, not just what is common in science.

Dr. Blanchard:

I find both rather hard to believe. But the big leap is deciding that life can spontaneously spring out of nothing. Once we've decided that that's possible, I really don't see that the idea of a giraffe emerging out of nothing is such a stretch.

I don't think the Mona Lisa example is comparable, because the face in the Moon and the Mona Lisa are not the same sorts of objects. Both a Giraffe and an Ur are (at least in theory) living creatures. For your example to work, we'd have to be comparing the Mona Lisa to another painting. Also, since the Giraffe actually exists and we have evidence to show it, I think it's more believable that the giraffe sprang out of nothing than the Ur organism, which might not even have existed.

The "or" in my statement did not mean that none of the ideas I mentioned could be combined. It simply meant that we probably have to believe in at least one of the things I mentioned.

I agree that many things happen spontaneously. But just as you think it is unlikely for giraffes to spontaneously appear, I think it is unlikely for living creatures in general to do so.

Lynn and William: I agree with you to a certain extent, although one has to be willing to declare certain parts of the bible metaphorical in order to also accept the idea that men evolved from apes. Dr. Blanchard has pointed to the fact that there are two creation stories in Genesis as evidence that they are intended to be metaphorical rather than historical, and that seems plausible - but I am hesitant to declare biblical stories metaphorical without knowing that they are. That opens the door to declaring the bits one dislikes metaphorical and those one likes literal. And when you begin doing that, there really isn't much of a point anymore, because if you're going to do what you like anyway, you can do that just as well without a religion.

[KB]

(My reply to Miranda continued):

4) Spontaneous events like fatal lightening strikes or the emergence of life from inorganic matter may be spontaneous only from the point of view of science. Presumably the Creator knows what He is doing. Science cannot include the Biblical God as a cause because such a cause is infinitely powerful. Only limited causes can be ruled in or out of consideration by experiment and evidence.

5) Miranda writes: "I am still not willing to concede that we came from slime molds. Or anything related to a Bonobo." This reminds me of a certain Protestant argument in favor of sexual reproduction: if God intended us to reproduce in a disgusting way, then we simply have to accept his will. Ergo: if something is challenging to our sensibilities, that does not mean that it isn't true or that it isn't God's will.

I reply that we are in fact slime molds. Our bodies and brains consist of nothing but cells. Those cells are arranged into a number of astonishingly complex organs, including the brain. Our ability to think, love, respond to the Creator with pious awe, all of these depend on the operation of neurons, synapses, etc. Or at least they do in this world. What makes us different from the slime mold is a human form, which is by definition a formal rather than material thing. I note as well that the human form is remarkably close to that of chimpanzees and bonobos. I do not find the Creator's work either disgusting or offensive in any of these cases. To the contrary, I am filled with awe.

6) I agree with Lynn and William that evolution and divine creation are perfectly compatible, at least with regard to creation. I do think there is a serious tension between Darwinian evolution and the Christian doctrine of sin. If the former is correct, then human sin is explicable. Our evolved dispositions are sometimes in tension with one another, and frequently they are in tension with our happiness. Ergo: we need laws, human and otherwise. If the latter is correct, then sin is inexplicable. If we had any natural reason to sin, the the Author of nature has to shoulder some of the blame.

But saying that only means that we have a problem. Einstein's relativity and quantum mechanics are mutually irreconcilable, yet physicists use both of them when they need to. Irreconcilable tensions are the great source of intellectual energy in our civilization, going back to Thomas Aquinas's attempt to reconcile the Bible and Aristotle. I am just trying to keep those tensions alive.

[KB]

Miranda: I think we may be beating this one to a stupor. But allow me to reply to your very interesting paragraph:

"I don't think the Mona Lisa example is comparable, because the face in the Moon and the Mona Lisa are not the same sorts of objects. Both a Giraffe and an Ur are (at least in theory) living creatures. For your example to work, we'd have to be comparing the Mona Lisa to another painting. Also, since the Giraffe actually exists and we have evidence to show it, I think it's more believable that the giraffe sprang out of nothing than the Ur organism, which might not even have existed."

Yes, the Mona Lisa is a painting and the moon, presumably, is not. But that is the whole point of the example. Occasionally natural things will come to look like something "spontaneously," i.e., without the input of a designing mind or some process other than mind that is capable of designing things. That's why a lot of natural formations get colorful names. Since that is true, what about something like the sphinx? It's a judgment call sometimes, but at some point an object displays sufficient order that we can be fairly sure that it did not arise spontaneously.

By that standard, we can be fairly certain that things that possess many of the characteristics of living organisms do arise spontaneously. I mentioned viruses and prions. Neither can exist without living organisms as hosts. The only plausible explanation is that they arose as by-products of natural organic processes and were shaped by natural selection. We cannot rule out bioengineering by angels and demons, perhaps; but I have said why such causes are invisible to science.

If prions, simple proteins, can spontaneously form into predators, I do not find it hard to believe that some molecule emerged spontaneously that had the property of self-replication. However plausible that may be, it is surely easier to believe in than the spontaneous generation of a giraffe.

Likewise, the existence of things like giraffes that are actually observed are not for that reason more compelling to rational belief than many things that cannot be observed. I cannot observe a dinosaur, but I have seen fossils. I believe in Tyrannosaurus Sue as much as I believe in giraffes. More than that, I believe in Sue's mother, for which I have no direct observation. Given the record of the tree of life, getting simpler as it goes back, I believe in the Ur organism and it's inorganic predecessors.

Lacking an alternative account, evolutionary theory looks as good to me geological theory, or chemistry and physics. I can't help thinking that there is no good reason not to believe this except that one is under the influence of the "OR". It's God OR Darwin. I just can't see any reason to believe in that OR.

[Teketel]

I think it is better to call Mr/Ms Evolution not Theory of Evolution. Because, according to Darwin & his followers Evolution is a being that can able to create, craft and shape all creations.