I began this series with a Bayesian interpretation of arguments from silence and then proceeded to use that interpretation to evaluate various arguments from silence about Jesus and God. In this post, I want to assess an argument from silence that is extremely popular with anti-evolutionists, an argument I call the “missing links” argument.

If we abbreviate “the fossil record does not contain any transitional fossils” as S, let B represent our background knowledge, and let E represent evolution, then the missing links argument can be summarized using the argument schema I outlined in Part 1, as follows.

(1′) S is known to be true, i.e., Pr(S) is close to 1.

(2′) Relative to background knowledge B, the prior probability of E is not very high, i.e., Pr(E | B) is not very much greater than 1/2.

(3′) ~E gives us more reason to expect S than E, i.e., Pr(S | ~E) > Pr(S | E).

(4′) Other evidence held equal, E is probably false, i.e., Pr(E | B & S) < 1/2.

Premise (1′) is false, but I shall not spend time on that here. I am also going to skip over for (2′). Instead, I want to focus on premise (3′). A recent endorsement of (3′) can be found in the book, Why I Don’t Have Enough Faith to be an Atheist, by Norman Geisler and Frank Turek (hereafter, “G&T”), who write:

If Darwinism were true, we would have found thousands, if not millions, of transitional fossils by now.[1]

Since it is implied that if Darwinism is false, we would not expect to find transitional fossils, it seems reasonable to interpret G&T as asserting (3’). For convenience, here it is again.

(3′) ~E gives us more reason to expect S than E, i.e., Pr(S | ~E) > Pr(S | E).

As it stands, however, (3’) is not obviously true. By itself, evolution doesn’t predict how many transitional fossils we would find today. Rather, by itself, evolution predicts that there were “thousands, of not millions,” of transitional forms, i.e. living beings. After a living being dies, its remains may or may not be destroyed (such as by decay or being eaten by other animals). If its remains are not destroyed, the remains may or may not become fossilized. If a dead organism is fossilized, that fossil may or may not survive intact to the present day. If the fossil survives intact to the present day, that fossil may or may not be found. If the fossil is found, it may or may not have preserved enough information to determine whether it is transitional. If the fossil preserves enough information to identify it as transitional, it may or may not have been examined yet by someone knowledgeable enough to identify it as such.[2]

The hypothesis of evolution says nothing about any of this. We get predictions about the number of transitional fossils only when we combine evolution with one or more auxiliary hypotheses about the frequency of fossilization, fossil preservation, fossil discovery, and fossil classification. G&T do not defend any of these auxiliary hypotheses and so their case for (3′) is, at best, incomplete. But it gets worse, for, as Mark Isaac as shown, there are good reasons to doubt all of the needed auxiliary hypotheses. The upshot is that (3′) is false.

ETA (20-May-14): Revised the wording of (2′) from “intrinsic probability” to “prior probability.”

Notes

[1] Norman L. Geisler and Frank Turek, I Don’t Have Enough Faith to be an Atheist (Wheaton: Crossway, 2004), Kindle location 2770-2771.

[2] Mark Isaak, “Index to Creationist Claims: Claim CC200.1” The TalkOrigins Archive (2005), http://www.talkorigins.org/indexcc/CC/CC200_1.html.