Re: Evolution's Imperative (was Def'n of Science)

Brian D Harper (
Mon, 15 Mar 1999 14:50:39 -0800

Hello again Vernon. Thanks for your comments.

At 11:36 PM 3/10/99 +0000, Vernon wrote:


>> Now, it seems to me that an attempt to falsify evolution shows
>> that evolution is falsifiable. Unless, of course, you can provide
>> some argument as to why such attempts were illegitimate.

>Before the true nature of the theory had been fully appreciated I
>suggest this was a perfectly natural creationist reponse, and hardly a
>ratification of evolution's falsifiability.

I suspect that the "true nature" you refer to has to do with
evolutionism rather than the science of evolution.

Anyway, I'd like to pursue this a little further. To this end,
I'll provide a concise statement of Popper's criteria :

A theory is falsifiable if one can conceive of observations
which, if found to be true, would render the theory false.

Now, I originally brought this up because I maintain that if
one looks at the history of science one will find that exactly
this has occurred. As an example, suppose you were transported
back to a time when the age of the earth was still an open
issue. You might then propose a test which determines the
age of the earth. If the earth is too young then one would
falsify any conceivable theory of evolution since all require
a great deal of time.

OK, so today we know that the earth is about 4.5 billion
years old, plenty of time. But the suggested test could
have turned out otherwise, which is the point of the
criteria. In fact, it was thought by many that this particular
test did refute evolution when, in 1862, Lord Kelvin used Fourier's
theory of heat conduction to estimate the age of the earth
at 98 million years, later revising this to 20-40 million

It turned out, however, that Kelvin was the one who got
falsified as he made a few assumptions which turned out
to be erroneous. Nevertheless, I surfed around a little
on the web this afternoon and found several creationist
web pages that repeat Kelvin's claims (minus rebuttal).

Needless to say, the authors of those web sites would
(should) not claim the evolution is unfalsifiable.

[skipping a little]

>> OK, let me try another idea. From what you say later I get the
>> impression that you think that enough evidence has been accumulated
>> to falsify evolution but that people are ignoring this evidence
>> because of some bias or whatever. Evolution then is unfalsifiable
>> for these people, they will believe it no matter what? OK, once
>> again this would be a reasonable use of the word unfalsifiable but
>> once again would not be what Popper meant by the word.

>I believe you are getting closer to the mark here. Kevin presented us
>with a number of falsification scenarios. (Perhaps Popper had some such
>idea in mind when he gave evolution his blessing.) However, all are
>illusory, I believe, for the reasons given in my earlier posting.

Maybe I missed it, but I cannot recall your giving any specific
reasons, only vague generalities.

Why don't you take the Kelvin example above and explain specifically
why this would not falsify evolution?

Also, let me make sure that my original point is clear. The faith
of true believers displayed by their ability to overlook disconfirming
evidence has nothing to do with whether their position can be

>ultimate scenario is a universe teeming with life - a logical
>consequence of Darwinian thinking. This expectation (clearly
>unfalsifiable) is the atheist's last resort.

I'm curious where you got this idea. Can you show the intermediate
steps in the logic? While your at it, here's a humorous quote
from George Gaylord Simpson which may cast some shadow of doubt
on your claim:

...There is even increasing recognition of a new science of
extraterrestrial life, sometimes called exobiology--a curious
development in view of the fact that this "science" has yet
to demonstrate that its subject matter exists.
-- G.G. Simpson

>> Popper says the theory has been well tested. How is this a failure
>> to apply his principles?

>I have not read this particular book. Did he elaborate on what he meant
>by 'well tested'?

This was from a paper instead of a book (citation given in my
original post). As best I can remember he does not elaborate
on "well tested" wrt the theory of evolution. The reason goes
back to my original caution. Popper was writing about the
controversy surrounding his original claims regarding the
testability of *natural selection*. Most of the paper concerns this.
He took a time out to write a few paragraphs to be sure to avoid
any possibility that some might conclude from his discussion about
NS that he also thought that evolution itself was not testable.
Nevertheless, the confusion remains, perhaps due to selective
quotation (unnatural selection :).

>> I would caution you against the argument from silence. It is
>> very weak.
>> Again, I invite you to re-read the quote from Popper. No where
>> does he suggest that evolution be accepted because of consensus.
>> He says instead that it is well tested. Thus he did not, as
>> matter of fact, seek an alternative criteria for evolution.
>I accept what you say, of course, but wouldn't you have supposed that
>peer pressure had a hand in it somewhere?

Kevin has already addressed this question admirably. But the main
point is that even if one were to grant this possibility (which
I would not), it is still not relevant since the peer pressure
would obviously be directed at what he changed his mind over,
i.e. the testability of natural selection. What I quoted had to
do with the testability of the theory of evolution. Its all very
clear if you read the paper. That paper may not be readily available
to those without access to a good library. You can find excerpts
from the original in <Popper Selections> edited by David Miller,
Princeton University Press, 1985. (see p. 239-246)

Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University