Susan mentioned that Creationists almost never mention Popper's
recantment. There are a couple of other things that also are
almost never mentioned ...
First, it is almost never mentioned that even before his
recantment Popper thought that natural selection was very
useful in serving as a metaphysical research program. It is
important to point out that a theory does not automatically
become unscientific because it contains a tautology. Can
anyone think of a scientific theory which does not contain
one or more tautologies? [hint: definitions are tautologies]
Second, it is very common to state or strongly imply that
Popper thought that evolution was untestable. It seems to
me that the quote which Susan responded to implied just
that. What Popper was dealing with, however, is natural
selection and not the theory of evolution. So, the second
thing that is almost never mentioned is that Popper felt
that the theory of evolution itself (which Popper took
to be common ancestry), in his own words, "has been well tested".
So, let's tell the whole story. If someone thinks it significant,
for some reason, that Popper once thought that natural selection
was a tautology, let's also mention that he changed his mind.
Not only that, let us also mention that there is something else
that he didn't change his mind about, namely that common ancestry
"has been well tested".
OK, here's the excerpts from Popper's famous recantment paper.
===========begin Popper========================================
1. _Darwin's Natural Selection versus Paley's Natural Theology_
[...]
The Darwinian Revolution is still proceeding. But now we are
in the midst of a counter-revolution, a strong reaction against
science and against rationality. I feel that it is necessary to
take sides on this issue, if only briefly; and also in a
Darwinian lecture, to indicate where Darwin himself stood.
My position, very briefly, is this. I am on the side of science
and of rationality, but I am against those exaggerated claims for
science that have sometimes been, rightly, denounced as
"scientism". I am on the side of the _search for truth_, and
of intellectual daring in the search for truth; but I am against
intellectual arrogance, and especially against the misconceived
claim that we have truth in our pockets, or that we can approach
certainty.
It is important to realize that science does not make assertions
about ultimate questions--about the riddles of existence, or
about man's task in this world.
This has often been well understood. But some great scientists,
and many lesser ones, have misunderstood the situation. The
fact that science cannot make any pronouncement about ethical
principles has been misinterpreted as indicating that there
are no such principles; while in fact the search for truth
presupposes ethics. And the success of Darwinian natural
selection in showing that the _purpose or end_ which an organ
like the eye seems to serve may only be apparent has been
misinterpreted as the nihilist doctrine that all purpose is
only apparent purpose, and that there cannot be any end or
purpose or meaning or task in our life.
Although Darwin destroyed Paley's argument from design by
showing that what appeared to Paley as purposeful design
could well be explained as the result of chance plus natural
selection, Darwin was most modest and undogmatic in his
claims. He had a correspondence with Asa Gray of Harvard;
and Darwin wrote to Gray, one year after the _Origin of
Species_:"...about Design. I am conscious that I am in an
utterly hopeless muddle. I cannot think that the world,
as we see it, is the result of chance; and yet I cannot
look at each separate thing as the result of Design."
And a year later Darwin wrote to Gray: "With respect to
Design, I feel more inclined to show a white flag than to
fire ... [a] shot ... You say that you are in a haze; I
am in thick mud; ... yet I cannot keep out of the question."
To me it seems that the question may not be within the
reach of science. And yet I do think that science has
taught us a lot about the evolving universe that bears
in an interesting way on Paley's and Darwin's problem of
creative design.
I think that science suggests to us (tentatively of course)
a picture of a universe that is inventive or even creative;
of a universe in which _new things_ emerge, on _new levels_.
[omitted description of various levels of emergence-- BH]
I think that scientists, however sceptical, are bound to admit
that the universe, or nature, or whatever we may call it,
is creative. For it has produced creative men: it has produced
Shakespeare and Michelangelo and Mozart, and thus indirectly
their works. It has produced Darwin, and so created the theory
of natural selection. Natural selection has destroyed the proof
for the miraculous specific intervention of the Creator. But
it has left us with the marvel of the creativeness of the
universe, of life, and of the human mind. Although science
has nothing to say about a personal Creator, the fact of the
emergence of novelty, and of creativity, can hardly be denied.
I think that Darwin himself, who could not "keep out of the
question", would have agreed that, though natural selection
was an idea which opened up a new world for science, it did
not remove, from the picture of the universe that science
paints, the marvel of creativity; nor did it remove the
marvel of freedom: the freedom to create; and the freedom
of choosing our own ends and purposes.
To sum up these brief remarks:
The counter-revolution against science is intellectually
unjustifiable; morally it is indefensible. On the other
hand, scientists should resist the temptations of scientism.
They should always remember, as I think Darwin always did,
that science is tentative and fallible. Science does not
solve all the riddles of the universe, nor does it promise
ever to solve them. Nevertheless it can sometimes throw
some unexpected light even on our deepest and probably
insoluble riddles.
2. _Natural Selection and its Scientific Status_
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
phenomenon 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.
excerpts can also be found in <Popper Selections>, edited
by David Miller, Princeton University Press, 1985.
===================end Popper================================
Brian Harper | "If you don't understand
Associate Professor | something and want to
Applied Mechanics | sound profound, use the
The Ohio State University | word 'entropy'"
| -- Morrowitz