Ted Cruz and the Edge of the Earth

In an interview with the Texas Tribune, Texas’s junior US Senator made a notably odd remark.

On the global warming alarmists, anyone who actually points to the evidence that disproves their apocalyptical claims, they don’t engage in reasoned debate. What do they do? They scream, “You’’re a denier.” They brand you a heretic. Today, the global warming alarmists are the equivalent of the flat-Earthers. It used to be [that] it is accepted scientific wisdom the Earth is flat, and this heretic named Galileo was branded a denier.

I’ve surveyed some ways that this “flat earth” theme has been abused in discussions of climate change before, and since Cruz is breaking some new denialist ground here, it seems worth reviewing the pertinent history.

Flat Earth News from December, 1980. Headline: "Galileo Was A Liar"December, 1980 edition of Flat Earth News (PDF link), proclaiming Galileo a hoax and decrying Pope John Paul II's willingness to apologize for Galileo's persecution. Flat earthers have no love for heliocentrism, but know better he wasn't the first to promulgate the idea of earth being a "grease ball" (in their derisive framing).

First, he’s either getting the trope wrong, or cleverly merging two denialist tropes into some sort of frightful chimera. The myth is that Columbus refuted the flat earth consensus, even though the (rough) sphericity of the earth was known at least by the time of Aristotle, and widely accepted (at least among the literate) by the time Columbus and Galileo lived. Not that modern flat earthers have any love for Galileo, but if one must recite a piece of mythology about the history of science, at least get the myth right.

Second, there was never a scientific consensus behind the flat earth. As I wrote when two climate change-denying researchers tried this gambit last year:

Christine Garwood reviewed that history in her comprehensive history Flat Earth: The History of an Infamous Idea. She notes that the idea of a flat earth is common in Middle Eastern religious cosmologies, including the ancient Egyptians, Sumerians/Babylonians, and early Hebrews. The ancient Greeks held a range of views on the shape of the earth, with some considering it flat, while others insisted it was cylindrical.

The Pythagoreans introduced the idea of a spherical Earth, but not based on scientific measurement. As worshippers of numbers and geometry, the Pythagoreans insisted that the Earth must take on the most perfect shape: the sphere. The idea of a flat or cylindrical earth persisted through the 5th century BCE, but the argument remained focused on questions of philosophy and theology, not on scientific observation. Plato surveys this range of views, and Garwood notes: “by the time [Plato’s] pupil Aristotle was writing, later in the fourth century BC, the globe concept seems to have become widely accepted among educated people.” … Columbus’ novelty didn’t rest in advancing a spherical earth, but in proposing a size for it that was far too small; this strategic misestimation was necessary to justify his belief that well-provisioned ships could reach the Indies by sailing west.

I think we can safely regard the flat-Earth cosmologies of the ancient Middle East as pre-scientific, and not reflecting a scientific consensus… Aristotle, Thales, and other Ancient Greeks set the stage for science and established some critical early results, but the notion of scientific consensus—a shared vision among a community of scholars united through a process of peer review and valuing evidence-driven, repeatable, testable hypotheses—would have to wait for a few millennia. In summary, then, there was probably never a scientific consensus that the Earth was flat, and that idea was first overturned not by science, but by a different philosophical system.

Indeed, the pertinent flat earth movement, one which challenged scientific consensus, wasn’t founded until the 19th century. And, like modern climate change denial, that movement never had scientific support, despite its adherents’ protestations of being “natural skeptics,” “plagued or blessed or whatever you want to call it by having a critical mind.”

The other item that Cruz combined into his denialist tropemanteau was the so-called Galileo gambit, an attempted analogy between the resistance faced by Galileo and that supposedly faced by the denier today. Generally it involves a reference to Galileo’s defense of heliocentrism, and the myth is advanced that his science was suppressed by theological and political opposition, a connection that makes more sense than Cruz’s suggestion that he was suppressed by the scientific establishment of the day. Carl Sagan famously dismissed the argument’s central analogy by noting: “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.”

Not only does the analogy fail to help deniers, and not only does Cruz’s account of Galileo not match up with the reality of Galileo’s work and life, but even if he’d gotten the myth right, it would still be a bit of misleading mythology. Galileo was not punished so much for advocating heliocentrism as for intentionally insulting his strongest defenders and arguing beyond what the available evidence would support. The Church was dubious of heliocentrism on theological grounds, but probably would have come around as evidence accumulated and some sort of learned consensus grew, had Galileo not handled the politics so poorly. It probably wasn’t wise to mock the Pope (putting his words in the mouth of a fool—unflatteringly named “Simplicio”— in a quasi-Socratic dialogue), alienate his political allies (whether the Church or the Medicis), or advance clearly flawed arguments (his heliocentric model of the tides would have predicted only one tide per day, yet his grand defense of heliocentrism rested heavily on that model).

In the past, I’ve mocked politicians for falling back on the “I’m not a scientist” slogan in responding to questions about climate change. But if the alternative to that dodge is to gather every denialist talking point and merge them into a Frankenstein monster, maybe they should have stuck to not being scientists.