What made Abraham Lincoln's speeches great? Geometry, according to the authors of a newly re-issued book about the 16th President.
It isn't so much the mathematical properties of space that influenced Lincoln's speeches as the principles of demonstration outlined by the ancient Greek mathematician Euclid.
"Euclid wrote thirteen books," says Dan Van Haften, co-author of Abraham Lincoln and the Structure of Reason. "The first six books covered plane geometry," Van Haften says, "and that's what Lincoln studied."
Van Haften's book, written with David Hirsch, isn't the first to prove Lincoln's fascination with Euclidean geometry. But it is the first to draw a direct connection to how Lincoln used Euclid in his Cooper's Union Address, the Gettysburg Address, and other speeches pivotal to his career -- and the nation.
Van Haften says he first noticed a reference to Euclid in one of the Lincoln-Douglas debates. When he mentioned this to Hirsch, the co-author encouraged him to study the mathematician to see if Lincoln's mention of Euclid was more than a passing reference.
Van Haften says he was reading the first book when he wondered if another scholar published a commentary. He found one in Proclus, a Fifth Century philosopher.
"And here in DeKalb at the NIU library," Van Haften says, "on the fourth floor, they have a copy of Proclus's commentaries on Euclid. And on page 159, it says that a proposition, if it has all its parts, has six elements -- an enunciation, exposition, specification, a construction, proof and conclusion."
This was Van Haften's "Ah-ha!" moment. He went back to Lincoln's speeches to see if they had these elements. "The first speech I looked at was the Cooper Union speech," he says, referring to an 1860 address Lincoln gave at the Cooper Institute in New York. The speech argued against the extension of slavery into the territories, and convinced eastern Republicans that Lincoln was a viable candidate for President.
"I saw Euclid's structure in the first third of the speech," Van Haften says. In the interview link above, the author explains the how the Gettysburg Address follows Euclid.
In both the Morning Edition and "full interview" versions, Van Haften talks about how the first edition of his book (released in 2010) influenced President Barack Obama's speeches. According to Van Haften, all of Obama's major addresses since 2011 feature the structure used by Lincoln.
Abraham Lincoln and the Structure of Reason is now out in paperback.
