Preposterous Universe

 
Juliette

Grading papers right now for our Moments in Atheism class. I figured that I would learn a lot from reading these (at least the good ones), and it's true. One of the students (Nicholas Boterf) found a wonderful quote in Juliette, a 1797 novel by the Marquis de Sade. Juliette is somewhat scandalized by the implications of what her "tutor," Madame Delbene, has been telling her:

"But ... if there be neither God nor religion, what is it runs the universe?"

"My dear," Madame Delbene replied, "the universe runs itself, and the eternal laws inherent in Nature suffice, without any first cause or prime mover, to produce all that is and all that we know."

I tend not to go along with some of the Marquis' ethical deductions from the godlessness of the world, but he got it exactly right with that quote.

For me, one of the rewards from looking at the history of these ideas was a better understanding of the change in perspective between Aristotelian mechanics and Galileo/Newton. Only now does it make sense why anyone would think the "first cause" arguments (Aristotle, Aquinas, etc.) held any weight at all. Aristotle thought that, to keep an object moving in a straight line, you had to keep pushing it. This seems silly to us post-Newtonians, but in fact it's pretty straightforward. Take a chair sitting on the floor and give it a push -- once you stop pushing, it will stop moving. "Aha," you say, "but that's only because of friction. If we ignore the friction, objects continue to move in straight lines unless forces act upon them." True, but highly non-intuitive. Why should we ignore friction, when it is ubiquitous in the real world abound us? Aristotle wasn't making a mistake, he was accurately describing the world he saw. If we take his description seriously, it's not so crazy to argue all the way to God. Lots of things in the world are moving, and moving objects require something to keep them moving, and ultimately that thing will be God.

Galileo's insight -- that the way to describe dynamics is to ignore friction and air resistance, find a simple model for the resulting motions, and then re-introduce friction afterwards -- was one of the most important moments in the history of science, and indirectly of religion as well. After he and Newton figured out conservation of momentum and the laws of motion, the Aristotle/Aquinas line of argument suddenly makes no sense. We don't need a "cause" or "mover" to explain why things are moving; that's the natural thing for them to do. This Newtonian revolution was, at a purely intellectual level, just as important as the Darwinian revolution for taking the philosophical wind out of religion's sails. After Newton, the primary justification for God shifted from cosmological arguments about first causes, to design arguments. Then Darwin made those seem silly (although Hume had done a pretty convincing job years before).

~ posted by Sean Carroll at 9:07 PM ~ link ~ ~ ~