[MUSIC] For Epicurus and his followers, the study of nature is the core of philosophy. In this respect, he distances himself even further from the Platonic picture than Aristotle did. Recall that according to Plato, what is truly real is purely intelligible form, while the natural world is made in its image. Aristotle dissents from this view, insisting that objects in the natural world are primary substances. Still, when he invokes the unmoved mover of the cosmos, he has in mind an immaterial entity. A god or gods whose purely intellectual activity is somehow or other the ultimate principle of the natural world. For Epicurus however, even the gods are fully within the natural world. As a follower of the pre-Socratic atomist Democritus, Epicurus takes the ultimate constituents of the natural world to be atoms and the void. Atoms are microscopic bodies of various shapes and sizes that are indivisible. That's what atom means in Greek. They move around in a void, bumping into each other, and rebounding off each other, and snagging onto each other to form complex bodies. The complex processes we observe and experience in the natural world are ultimately to be understood as atoms moving in the void. For example, vision involves streams of atoms emanating from visible objects and reaching our eyes where they interact with the very fine grained atoms that constitute our souls. The motions of these soul atoms spread throughout the interior of our bodies account for all the life activities. This is more or less the picture that Democritus held. And for which Aristotle made fun of him. In Epicurus' view, all the phenomena in what Aristotle calls the sublunary world can be accounted for by atomic motions. He doesn't see the need to invoke an immaterial unmoved mover in order to explain why there is change and why it is continuous. He thinks atoms and their natural motions are all we need to invoke. Atoms have always existed and will never perish and they are always in motion. There is however, a question for which Epicurus thinks we do have to invoke a cause beyond the natural motions of atoms. And to answer this question, he develops a doctrine that is as famous or notorious as the doctrine of the unmoved mover. This is the doctrine of the atomic swerve. Here's why he thinks we have to suppose that atoms sometimes swerve off their determined course. Suppose we conceive of atoms in the way Democritus did, as possessing only weight and thus having only downward motion with every atom falling at the same speed. Suppose as well, that the void is infinite. So each atom can travel downwards forever without encountering an obstacle. Putting these two principles together, we should expect that all the atoms in the universe would be moving downwards, parallel to each other, and at the same speed. Like a steady rain of particles throughout the universe. No atom would ever collide with another to initiate the complex chain reactions that generate the complex bodies and processes of the sort we are familiar with in the natural world. So the original atomic theory of Democritus does not have the resources to explain how these atomic interactions got started, so Epicurus proposes a refinement, or addition, to that theory. In addition to their primary downward motion, atoms sometimes swerve very slightly from their downward course. Not very often and not very much, just enough to get interaction going in the first place. After which collision, cohesion, and various chain reactions on mechanical principles can account for all the rest. Epicurus thinks that something like the swerve had to have happened in order for the world as we know it to have come to be. But as to the patterns and regularity at the macro level in the world as we know it, that Aristotle would explain by invoking goal-directed processes in nature, and that Plato would explain by invoking a demiurge, aiming at the good of the whole universe, Epicurus insists that there is nothing there to explain. Our complex world is just one of the many ways complex atomic interactions could have ended up, given the basic atomic structure and motions. And indeed, there are infinitely many worlds which actually exist out there somewhere. All of them realizing the infinitely many possibilities that the atomic theory allows for. While there might be features of our own cosmos that strike us as good or well-designed, Epicurus says there is no designer. That's just how it turned out in our world. There are plenty of other worlds where it didn't turn out this way. Where there is goodness in a cosmos, it just happened that way with nothing aiming at it or guaranteeing it would come about. As Epicurus says in the letter to Herodotus, movements, turnings, eclipses, risings, settings, and related phenomena occur without any god helping out and ordaining. As the Epicurean speaker in Cicero's On the Nature of the Gods says, the world was produced by nature, and there was no need for someone to make it. Nor is there any need to posit gods at work within the world, as on the popular views attributing meteorological phenomena and earthquakes to the gods. Epicurus is very much in the tradition of the pre-Socratic naturalists who proposed that these can be accounted for in purely material terms. The letter to Pythocles gives material accounts of lightning, thunder, tornadoes, earthquakes, wind, hail, snow, dew, rainbows, and comets. All without invoking the gods. Now, does this mean that the Epicureans didn't believe in God or gods? They were in fact often suspected in antiquity of being atheists, but this was a charge they vehemently denied. Of course the gods exist, Epicurus insists. The concept, or ennoia, of God is something every people has, he claims, and so it must be true. Indeed, he even goes so far as to claim that the gods are anthropomorphic, human formed, since that is part of the universal conception of the gods. Epicurus proposes that there must be entities that meet our preconception of anthropomorphic gods and they must exist somewhere or somehow in the cosmos, or perhaps in the interstices between the different cosmoses, according to one of our sources. In one notoriously difficult passage, we are told that Epicurus proposed that the gods are streams of images, flowing from our perceptual faculties, or perhaps flowing to them. There are textual difficulties with our sources here. Now does this mean that the gods are simply images or projections of our imaginations? Our evidence is too scanty to say with any certainty, although Epicurius did clearly insist that the gods are appropriate objects of worship. He says, the excellent nature of the gods would be worshipped by pious men because of that nature's blessedness and eternity.
