Thursday, August 8, 2013

Text on Trial: Origins of Geocentric Theory

Our Textboook: "This earth centered view of the universe, called the geocentric theory, was supported by more than just common sense. The idea came from Aristotle, the Greek philosopher of the fourth century B.C."

"Ancient societies were obsessed with the idea that God must have placed humans at the center of the cosmos (a way of referring to the universe). An astronomer named Eudoxus created the first model of a geocentric universe around 380 B.C." Source:

"Aristotle developed a more intricate geocentric model (which was later refined by Ptolemy), general cosmology clung to these misconstrued ideas for the next 2,000 years." Source:

Discussion: Our class text states that the geocentric theory "came from Aristotle", ignoring anyone who may have influenced Galileo. This an offense of context as well as, potentially, of discovery.
An offense of context occurs when the text presents a topic with little of no background information. I suspect we will find these context offenses frequently.

Another source discusses Eudoxus: "Perhaps Eudoxus’s greatest fame stems from his being the first to attempt, in On Speeds, a geometric model of the motions of the Sun, the Moon, and the five planets known in antiquity. His model consisted of a complex system of 27 interconnected, geo-concentric spheres, one for the fixed stars, four for each planet, and three each for the Sun and Moon. Callippus and later Aristotle modified the model. Aristotle’s endorsement of its basic principles guaranteed an enduring interest through the Renaissance."

Note: More research needs to be done. I am suggesting, however, that stating "the idea came from Aristotle" demands further investigation.

Here is a link to a version of Aristotle's On the Heavens, as well as a Wikipedia overview of the text.
Aristotle begins to discuss the earth in Book II, Part13. (Book II, Part 13 in a google doc )


  1. I realize that your are teaching Western Civ, but this is also very Eurocentric. Might be interesting to get students speculating about whether or not folks outside of Europe developed any ideas about the cosmos...I just bought a copy of The Renaissance Bazaar, which explores the links between European Renaissance thought and the rest of Afro-Eurasia.;jsessionid=ADBA9F157952CCEA71E14AAACC5E024F?cc=us&lang=en&

  2. Thanks for the feedback, I found this source to start my inquiry:

    Besides AP Euro courses, I haven't meant many teachers who teach Western Civ. So many schools offer two years of World History. Wondering if we will change to that model.