20 Evolution and the Fossil Record
- Special Pleading and Ad Hoc Hypotheses
In science, when an observation comes up that appears to falsify your hypothesis, it is a good
idea to examine the observation closely or run the experiment again, to be sure that it is real.
If the contradictory data are sound, then the original hypothesis is falsified, dead, kaput. It is
time to throw it out and come up with a new, possibly better hypothesis.
In the case of many nonscientific belief systems, from religions to mysticism to Marxism,
it does not work this way. Belief systems often have a profound emotional and mystical sig-
nificance for people. They exist in spite of contradictory observations, and people refuse to
let rationality or the facts shake them. As Tertullian put it, “I believe because it is incredible.”
Saint Ignatius Loyola, the founder of the Jesuits, wrote, “To be right in everything, we ought
always to hold that the white which I see is black, if the Church so decides it.” That’s fine, if
you are willing to accept that system and suspend disbelief of some of their claims for a more
important benefit of emotional and mystical connections.
If you pass off your belief system as science, however, you must play by the rules of sci-
ence. When con artists try to sell you snake oil, and someone points out an inconvenient fact
about it, the con artists will try to attack this fact or explain it away with an “after the fact”
or ad hoc (Latin for “for this purpose”) explanation. If the snake oil fails to work, they might
say “you didn’t use it right” or “it doesn’t work on days when the moon is full.” If the séance
fails to contact the dead, the medium might scold the skeptic by saying, “you didn’t believe
in it sufficiently” or “the room wasn’t dark enough” or “the spirits just don’t feel like talk-
ing today.” If we point out that there are millions of species on earth that could not have fit
into the biblical Noah’s ark, the creationist tries to salvage their hypothesis by saying “only
the created kinds were on board” or “insects and fish don’t count” or “God miraculously
crammed all these animals into this tiny space, where they lived in harmony for 40 days and
40 nights” or some similar garbage.
As we shall see in the chapters that follow, ad hoc hypotheses are common when the
conclusion is already accepted and the believer must find any explanation to wiggle out of
inconvenient contradictory facts. But they are not acceptable in science. If the conclusion is a
given and cannot be rejected or falsified, then it is no longer scientific. - Not All “Persecuted Geniuses” Are Right
People trying to promote wild ideas that seem crazy to us will often point to the persecu-
tion of Galileo (arrested and tried for advocating Copernican astronomy) or Alfred Wegener
(ridiculed for his ideas about continental drift) and take solace in how these geniuses were
eventually proven right. But as Carl Sagan (1996:64) put it, “The fact that some geniuses
were laughed at does not imply that all who are laughed at are geniuses. They laughed
at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also
laughed at Bozo the Clown.” The annals of science are full of wild and crackpot notions that
didn’t survive testing and were eventually abandoned, and they far outnumber those of the
handful of “misunderstood geniuses” who were vindicated in the end.
These misunderstood geniuses often turn to Schopenhauer, who wrote, “All truths pass
through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted
as self-evident.” But Schopenhauer is wrong. Many revolutionary and radical ideas (such
as Einstein’s theory of relativity) were never ridiculed or violently opposed. In the case of
Einstein, his theories were mostly ignored as interesting but untested until scientific observa-
tions made in 1919 corroborated them.