Thursday, December 2, 2010

The War Between Fact and Theory

Another message board had the following exchange: 

A: So much of what is taught in school is still technically "Theory" even as it is being taught as fact - like The Big Bang, for instance.

B: The statement quoted above mostly just signals a rather low level of scientific literacy--a lack of awareness of how the words "fact" and "theory" are typically used in science and how that usage differs from the vernacular.

Now my own peculiar experience is that many folks who make the latter point understand the difference no better than those who make the former.  This includes scientists, who frequently make very poor philosophers.  (The distinction between theory and fact is a philosophical one, not a scientific one.  Neither theories nor facts are physical bodies measurable by science.)  There are those who suggest, for example, that a theory that has been verified a great many times becomes a fact.  This is a little like saying that a baseball team that wins a great many games becomes a base hit. 

The Layer Cake of Science

The distinction between Fact, Law, and Theory was laid out by the logical positivists of yore.  These were philosophers of science like Poincare, Mach, Duhem, and Einstein that P.Z.Meyers once derided as running alongside the mighty Locomotive of Science, hollering advice and observations to the likes of the puissant Baconian engineer P.Z.Meyers. 

Start from the bottom, at which we find Empirical Experiences.  Things that we see, hear, feel, etc.  Both science and philosophy start here, but move in different directions.  The scientific direction runs thusly:

1. Facts.  When these experiences can be operationally measured, they become facts.  Factum est being the participle of "to make," a fact is "something made," a "feat."  Measurement creates facts because the same thing measured in two different ways will often produce two different results.  The experiment is the premier fact-producing machine, but facts may also be made by meticulously described qualitative observations, such as those Darwin made.  (The distinction is oft expressed as between "active" and "passive" statistics.) 

2. Laws.  Regularities or patterns in the facts are called laws, especially when they can be expressed in mathematical terms.  But they can also be expressed verbally.  Newton originally did so.  The equations associated with his three laws came later - and don't quite correspond to the three laws as he actually stated them.  There is no math at all in Darwin, but he did enunciate some laws or principles of evolution. 
3. Physical Theories.  These are stories or narratives in the context of which a specified body of facts "makes sense."  Newton's theory of gravitation "made sense" of Kepler's astronomical observations and mathematical laws.  Given a physical theory, the natural laws may be deduced and the facts predicted.  When facts are predicted beyond those originally used to develop the theory and then are subsequently found, the theory is further supported.  But no amount of support will change a theory into a fact, as such. 

The Third Wave positivists regarded theories as neither true nor false, but only useful. 

As an illustration, consider the following: 
1. Facts: the motions ("falling") of heavy bodies
2. Laws: s=0.5gt^2, F=ma, F=G(M*m)/d^2, etc. 
3. Theory: "gravity".  Newton's spooky action-at-a-distance (a force field put out by the mass which attracts other masses); superseded by Einstein's warpage of the field of Ricci tensors defining space, so that bodies travel down the geodesics thus created. 

No amount of confirmations will establish "gravity" as a fact.  Only the actual physical motions of material bodies are facts.  "Gravity" remains simply a useful story that "makes sense" of the local motions of bodies under a very wide range of circumstances.  When you look at it closely, it is tautological.  Why do bodies move in such a fashion?  Gravity.  How do we know there is gravity?  Because bodies move in such a fashion. 

Facts are effects, observation of concrete singulars grasped by the senses.  Theories are principles, universals grasped by the intellect.  Universals - or Natures - do not have material existence, which is why materialists (who typically deny the existence of natures or essences) grow very confused and often treat theories as if they were facts. 

Conspiracy Theories, or
Covering Your A Posteriori
Now, if supporters of evolution confuse well-founded theories with facts, opponents confuse theories with unfounded guesswork.  They are not that, either.  Bishop Grosseteste's method of resolutio et compositio reasoned from the quid (the what) up to the propter hoc (the reason why) and then back down again.  This became the demonstrative regress developed by the Jesuits in Padua and Rome and taught to Galileo; and ultimately, the methods of the positivists. 

Induction is a fallacy in formal logic; but science is not formal logic.  Propositions never stand in isolation and are never divorced from the material world.  If we see a strange baseball on the carpet of the dining room, broken glass in the window (likewise on the carpet), and in the distance fleeing young boys with gloves and bats, it is a formal logical fallacy to conclude that they have thrown or hit the baseball through the window.  But it is also what Aristotle called a demonstration, in the Posterior Analytics. 

Thus, the explanation (theory) does not come from nowhere, but is abstracted from the facts.  However, too many Later Moderns stop with a demonstration, which I think is why Popper was able to reduce science from "certain knowledge" (science) to "probable knowledge" (opinion). 

But Grosseteste, Zabarella, Lorinus, and Vallius [from the latter of whom Galileo carefully copied his Tractatione de demonstratione] did not stop with the a postiori demonstration, but proceeded to an intermediate stage: "the work of the intellect" in which it is shown that no other explanation can account for the effects.  Then, proceed deductively a priori from the cause back to the effects, now properly understood as effects.  In the course of this, additional quia (effects) may be predicted and then diligently sought for additional confirmation. 

The conspiracy theorist, we now see, is very good at tying facts together with an all-encompassing explanation, but is not so good at the work of the intellect; that is, at considering other possible explanations for the same facts. 

The Evolution of Evolution

So, is evolution a fact or a theory?  Yes and no.  Yes, if you fall into equivocation on the meaning of the term "evolution."  The term originally referred to the "rolling out" of a scroll for reading (and an extension of this physical meaning persists when we say that a marching band performs evolutions on the football field).  In biology, it refers to the unrolling of new actual species out of the potentialities of older species.  We encounter the idea first in Augustine of Hippo, who reasoned that creation had been instantaneous (since time was created along with everything else) and so whatever arose later must have arisen from the rational powers possessed by existing matter.  We encounter the same notion much later in Aquinas, who writes:

Species, also, that are new, if any such appear, existed beforehand in various active powers; so that animals, and perhaps even new species of animals, are produced by putrefaction by the power which the stars and elements received at the beginning.
Species etiam novae, si quae apparent, praeextiterunt in quibusdam activis virtutibus, sicut et animalia ex putrefactione generata producuntur ex virtutibus stellarum et elementorum quas a principio acceperunt, etiam si novae species talium animalium producantur.

The interesting thing is that, even though the science of his day was deficient, he supposed that new species arose by natural causes inherent in what existed before them.  (And that these pre-existent causes were implicit in nature from the beginning.)  We now understand this as the new species existing potentially in the genome of a prior species, in that this or that mutation might transform one genome into another, as the "viable" word CUT may arise by a mutation of the vowel from the equally viable word CAT.  A simplification that will do for now.

Now, it is quite clear that new species or kinds have arisen over time, so evolution is a fact insofar as the term means "change in a species over time."  It is actually a "body of facts." 

However, science is no more a pile of facts than a house is a pile of stones, as Poincare observed.  What is needed is a story that makes sense of these facts.  That is, we must make the a posteriori demonstration from the effects to the cause.  Darwin and Wallace did so by inductively reasoning; so did Lamarck and others.  These are theories of evolution, that is: explanation of the facts of evolution.  We can sum this up nicely by saying

"Evolution is a fact; natural selection is a theory."

The Worm in the Apple

But if there is one thing that Late Modern Analytic philosophy has shown is that science is underdetermined.  That is, no matter how diligent the "work of the intellect" it is not always possible to eliminate all other possible explanations of the facts.  So far, there is no experimental distinction between Einstein's theory of relativity and Milne's kinematic theory of relativity.  One may deduce the very same laws and facts from both theories.  There are at least three (and iiirc, more) theories of quantum mechanics: the Copenhagen theory, the many-worlds theory, and Cramer's transactional theory.  Again, all three theories account for the same facts.  It is really only in this sense that "a scientific theory is one that is falsifiable."  It is not that in order to be scientific is must be falsifiable.  We cannot falsify the sphericity of the moon.  There really is no other explanation for the phases of the moon.  But perhaps the Afshar experiment falsified the Copenhagen and many-worlds theories in favor of the transactional theory.  (Copenhageners and Many Worlders deny this.)  In any case, some experiment or new observation might do so. 

An oft overlooked statement by ID proponent Michael Behe is that he does not deny that evolution occurs, nor that natural selection accounts for the bulk of it.  But he contends that the struggle for existence by the organism and the consequent differential survival of "favored races" does not account for the development of biochemical structures.  His notion that this "proves" the existence of God is theologically unsound (see Summa theologica, pt I Q2 art3, fifth way).  However, it is entirely possible that the theory of natural selection may fail to account for all evolution (in the sense of change over time).  Gravity does not account for all motion; electromagnetism is needed for some of it! 

The way some supporters use it, "natural selection" borders on tautology and is stretched to mean either "evolution" itself or "any change over time due to natural causes."  In many cases -- the "just so stories" that bugged Gould and others -- it is simply used for the a priori half to reason deductively from the theory to some selected fact, showing "this is how it could have happened," and skipping the vital a posteriori step, which might establish that "this is how it did happen." 


  1. Well said. In particular, "However, it is entirely possible that the theory of natural selection may fail to account for all evolution (in the sense of change over time). Gravity does not account for all motion; electromagnetism is needed for some of it!"

    As you know, there is a sizable (and aggrieved) body of molecular biologists who think genetic drift, as a major driver of evolution, gets no respect--along with the other kinds of stochastic processes ordinarily subsumed under the breezy term "random mutation".

    For what it's worth. :)

  2. Flynn's theory of evolution runs thusly:

    Mutations happen.
    Internal genetic machinery accommodates the mutation to the rest of the genome.
    Some mutations destroy the organism or render it non-viable. This is where natural selection plays.
    For all other mutations, the organism possessing it finds some way to make use of it or works around it. If needs be, it will exploit a different niche than its ancestors. This is like painting the bulls-eye around the arrow.

    The old bit about the polar bear becoming white "in order to" blend into the environment: what did these bears do before they became white? Die off? During the winter, the polar bear hunts seals by waiting near the breathing holes and whacking the seals when they pop their heads out. Blending in has no advantage, since the seal cannot see the bear before it emerges to its doom.

  3. I think it was St. Albert, in his geography book where he ripped on St. Augustine's antipodes ideas, who theorized that arctic animals would have to be white for some sort of fittingness reason. (Since he probably got as far as Poland or Russia, this theory may have been cheating somewhat.)

    The current explanation is apparently that polar bears' fur is clear, for better absorption of sunlight into the skin through such thick warm fur; but it appears white to our eyes. So what happened before was that polar bears had thick warm dark fur, which assisted absorption of sunlight into the top layer of their fur and helped them hide in the woods. But they probably had trouble getting enough Vitamin D, except by eating things.

  4. The fundamental problem is that we can always spin a theory to explain why a thing is as it is. Had the polar bear dark fur, I dare say we could come up with an explanation. (By freezing in place while stalking, the dark-polar bear appears to be a rock on the landscape to the seal, who then disregards it. The bear learns not to move while the seal is looking its way.)


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