History of Philosophy II Lecture Notes

Phil A212

William Jamison

Lecture 1 Notes:

Copernicus, Kepler, and Galileo

Discussion topic: Why does this selection from Copernicus demonstrate the importance of convincing Pope Paul III that Copernicus does not mean to challenge orthodoxy but only attempts to show that mathematicians have only made a mess in their attempts to describe the organization of the universe? Looking at the views of others, such as Cicero, and taking the model of the universe with the sun as the center enables the mathematics to match observations much more precisely.

Did Copernicus, Kepler, and Galileo all think they were only working with various models of the universe (solar system or geocentric system) or did they speak as though only one model was correct?

It seems like they thought only one model was correct and the other model was an error.

Today our Postmodern view leads us to think of each model as useful from a particular perspective. The solar system is certainly more mathematically beautiful and useful for space exploration and ease of predicition. The geocentric model (with appropriate corrections! Such as: only the moon and the sun go around the earth and all the other planets go around the sun as it goes around the earth, with their moons going around their planets as their planets go around the sun and the sun goes around the earth, etc.) has its usefulness also. It seems intuitively important to us that we are the center of our universe. Even in an Einsteinian universe, each of us are the center of space-time and the earth is the logical center of the universe. Notice that a perspective can be logically incorrect. The main trouble with the geocentric model of Ptolemy was that the positions of the planets did not match observations. A contemporary geocentric model, such you may find in a planetarium, focuses the stars and planets from a central point in the room, and is more accurate the more detailed and expensive it is.

This is an important point. Just because our postmodern view considers all perspectives valuable for what they teach us does not mean that a perspective is logically correct according to its own system. We may ask if logic is always an issue for a perspective to be useful or not.

We could also point out that a contemporary Postmodern perspective may view it logically correct to view a geocentric model as possible only if a solar centered model is also correct! How could the one be logically possible without the other? As we expand our view to increasingly wider perspectives are we finding the logical implications of those earlier perspectives? Is this what we mean by progress?

There are other perspectives available that consider neither the sun nor the earth going around one another. Both can be viewed as on the same plane remaining relatively at opposites ends of a line, for example. In space-time the earth may be viewed as traveling in a straight line while the fabric of space is curved. What other perspectives are possible today? Why is it incorrect today to think of any one perspective as the way reality really is?

Next reading assignment:

Descartes, "Meditations on First Philosophy"