Carl Sagan's no evidence claim

Joel Cannon (
Mon, 29 Sep 1997 15:01:26 -0600 (CDT)

In hopes that someone might find it useful here is an excerpt from my
critique of the movie "Contact", which has been (thankfully) edited
extensively since I posted a premature version here. I believe that
this critique applies equally to any naturalistic claims
(e.g. Dawkins, and Dennet) that science provides a privileged
viewpoint for looking for evidence of God.

The complete critique can be read at or if you want I can send
you a copy.

Concerning Sagan's "No Evidence" assertion:

{\bf A Dissenting Opinion}\\ It looks dark indeed for Christians when
an internationally renowned astronomer applies the same techniques he
used to unlock Mars's secrets to investigate our God and finds no
evidence of the His existence. Thankfully, closer scrutiny
produces a brighter outlook. Sagan confuses assumptions for evidence,
and provides sufficient personal data to discredit his claim to go
only where evidence leads him.

Indeed, the dubious logic in Sagan's ``no evidence'' claim bears an
instructive symmetry to the Russian Cosmonaut Yuri Gugarin's statement
after returning from the first manned space flight: He knew God didn't
exist because he had looked for and not found God while in outer
space. The algorithm: Make an assumption of God's signature--if you
don't find it you can safely conclude God's non-existence.

Like Gugarin, Sagan's claim's central feature, his ``no evidence''
assertion rests directly on assumptions, specifically:
1) his assumptions concerning God's nature (which is at odds with
Judaism, Christianity, and presumably Islam); and 2) his assumption
concerning the likelihood that God exists.

Before Sagan could look for evidence, he had to assume or determine by
empirical means what might constitute valid evidence. Deciding just
how God could or couldn't act could not be tested empirically so he
had to make assumptions about the character and action of
God. Arguably, in this case Sagan was likely to guess wrong, casting
doubt on his conclusions. Garbage in--garbage out; bad assumptions
yield bad answers.

In the case of God's existence, the only evidence Sagan would accept is the
miraculous violation of the laws of cause and effect. Sagan assumes
that any self-respecting deity would interrupt the natural flow of his/her
creation so that even the most skeptical scientist could be convinced.
Interestingly, in the book {\it Contact}, Ellie suggests some means by
which God could do this such as ``a monster crucifix orbiting the Earth.''
or ``the surface of the moon covered with the Ten Commandments '' (p. 164).
Perhaps less evidence for biological evolution might also have made Sagan
more inclined to trust the Almighty.

Sagan's failure to find flying crosses or holes in evolutionary theory
may entail God's non-existence but that seems dubious. Bad assumption
might be a better conclusion; God need not operate in the miraculous
way Sagan expects him to. Or perhaps God's secure self-image may
preclude having to prove himself to every gun-slinging scientist
challenging his existence.

Note that which alternative one chooses from these or other choices
depends strictly on one's prior assumptions concerning God, rendering
Sagan's ``data'' useless as an empirical test. If you begin thinking
it probable God exists you reject Sagan's interpretation (and vice
versa). The ``evidence'' doesn't change peoples minds; only reinforces
prior prejudices. To claim otherwise, as Sagan does, is sheer
self-deception. Like the Cosmonaut, he's failed to see that his
assumptions determined his conclusion.


Joel W. Cannon
Dept. of Physics
Centenary College of Louisiana
P. O. Box 41188
Shreveport, LA 71134-1188

(318)869-5026 FAX