Let me reformulate my problems with Patterson’s piece.
Firstly the “claptrap” (as I previously described it) that is taught to Americans about Columbus, from a young age, can more easily be placed in the context of an American tendency to valorise and mythologise its history, than to a specific desire to miscast historic understanding of the shape of the Earth. Given Rightwing (including Religious Right) preference for this valorised version (observable from their complaints about less valorised approaches), it would not be surprising that students at an institution like Biola demonstrate this in an exaggerated manner.
This suspicion is further heightened by the fact that Washington Irving is widely cited for perpetuating this myth in his book A History of the Life and Voyages of Christopher Columbus.]
Looking beyond Columbus, the two footnotes whose sources I tracked down above demonstrate an exaggeration and mischaracterisation of those sources.
Looking further, we see an attempt by a misguided pair of Christian demographers to offer up Flat Earth as another ill attributable to Christianity. Hardly probative.
And we have the words of Jeffrey Burton Russell:
in reality, there were no skeptics [of a round earth]. All educated people throughout Europe knew the earth’s spherical shape and its approximate circumference.
I’m sorry, but in spite of Russell having written a “book–length study” on the topic, this statement would appear to be directly contradicted by the views expressed by Cosmas Indicopleustes, as I noted above.
[Addendum: in the Wikipedia article on the subject, Russell is quoted as saying something slightly different:
with extraordinary few exceptions no educated person in the history of Western Civilization from the third century B.C. onward believed that the Earth was flat
“All” or “with extraordinary few [but some] exceptions”?
Every time I look more closely at this issue, it gets murkier.]
Given all this, the fact that Patterson appears to be relying in part on Michael Keas (and previous exposure to him has failed to yield observable daylight between him and the DI apologetic party line) and his book, the fact that he is primarily a historian of Christian Thought rather than of Science, and who teaches at a religious institution, I cannot help but think that an overly apologetic view or framing of this issue may have influenced his views on the matter.
In short, it is becoming unclear which of the Myth of Flat Earth and the Myth of the Myth of Flat Earth is the more mythical.