>Of course neither
>of these calculations have much bearing on reality, but they draw attention to
>an important fact: The theory of evolution, as it is currently framed, whether
>by intent or by circumstance, is not falsifyable. This is what lead science
>philosopher Karl Popper to criticize the theory of evolution in the same way
>he challenged other theories in vogue, such as Marxist economics and Freudian
>psychology. To Popper, the most impressive scientific theories were those that
>could be subjected to daring, potentially falsifying experiments, like
Einsteins
>theory of relativity. In stead, what Karl Popper found were investigators
intent
>only on seeking evidence to *confirm* the theory. One may wish to argue that
>falsifying experiments DO exists, but only after surrendering the above
>probability estimates.
Karl Popper's views on falsifiability and evolution come up every once in
a while on talk.origins. I looked into it awhile back and thought I would
share some of what I found.
First, it was natural selection (not evolution) that Popper originally
claimed was a tautology and thus not falsifiable. The reason I say
"originally" is that Popper later recanted this view.
Following is an excerpt from the paper in which he makes this recantment:
===============================================================
When speaking here of Darwinism, I shall speak always of
today's theory--that is Darwin's own theory of natural
selection supported by the Mendelian theory of heredity,
by the theory of the mutation and recombination of genes
in a gene pool, and the decoded genetic code. This is an
immensely impressive and powerful theory. The claim that
it completely explains evolution is of course a bold claim,
and very far from being established. All scientific theories
are conjectures, even those that have successfully passed
many and varied tests. The Mendelian underpinning of
modern Darwinism has been well tested, and so has the theory
of evolution which says that all terrestrial life has evolved
from a few primitive unicellular organisms, possibly even
from one single organism.
However, Darwin's own most important contribution to the
theory of evolution, his theory of natural selection, is
difficult to test. There are some tests, even some
experimental tests; and in some cases, such as the famous
phenomenom known as "industrial melanism", we can observe
natural selection happening under our very eyes, as it were.
Nevertheless, really severe tests of the theory of natural
selection are hard to come by, much more so than tests of
otherwise comparable theories in physics or chemistry.
The fact that the theory of natural selection is difficult
to test has led some people, anti-Darwinists and even some
great Darwinists, to claim that it is a tautology. A tautology
like "All tables are tables" is not, of course, testable; nor
has it any explanatory power. It is therefore most surprising
to hear that some of the greatest contemporary Darwinists
themselves formulate the theory in such a way that it amounts
to the tautology that those organisms that leave the most
offspring leave the most offspring. And C.H. Waddington even
says somewhere (and he defends this view in other places)
that "Natural selection ... turns out ... to be a tautology".
However, he attributes at the same place to the theory an
"enormous power ... of explanation". Since the explanatory
power of a tautology is obviously zero, something must be
wrong here.
Yet similar passages can be found in the works of such
great Darwinists as Ronald Fisher, J.B.S. Haldane, and
George Gaylord Simpson; and others.
I mention this problem because I too belong among the
culprits. Influenced by what these authorities say,
I have in the past described the theory as "almost
tautological", and I have tried to explain how the
theory of natural selection could be untestable
(as is a tautology) and yet of great scientific
interest. My solution was that the doctrine of natural
selection is a most successful metaphysical research
programme. It raises detailed problems in many fields,
and it tells us what we would expect of an acceptable
solution of these problems.
I still believe that natural selection works this way as
a research programme. Nevertheless, I have changed my mind
about the testability and logical status of the theory of
natural selection; and I am glad to have an opportunity
to make a recantation. My recantation may, I hope,
contribute a little to the understanding of the status
of natural selection.
-- Karl Popper, "Natural Selection and the Emergence of Mind",
_Dialectica_, vol. 32, no. 3-4, 1978, pp. 339-355.
=====================================================================
I found Popper's recantment a little surprising. I had heard so much about
it on talk.origins that I was really expecting something more forceful than:
Nevertheless, really severe tests of the theory of natural
selection are hard to come by, much more so than tests of
otherwise comparable theories in physics or chemistry.
Consider also that the paper was originally presented as the first Darwin
Lecture at Darwin College, Cambridge.
========================
Brian Harper |
Associate Professor | "It is not certain that all is uncertain,
Applied Mechanics | to the glory of skepticism" -- Pascal
Ohio State University |
========================