Chapter 9

17 Yet none of them speaks that way: mastering these contortions of language is a greater task than mastering the rising and setting of the constellations. But let us return to that argument of Diodorus which they call the argument “on possibilities,” an inquiry into the meaning of what is possible. Diodorus holds, then, that only what is true or will be true is possible. This bears on the claim that nothing happens which was not necessary, and that whatever can happen either already is or will be; that statements about the future can no more change from true to false than statements about the past. In past events, however, the unalterability is plain, while in some future events, because it is not plain, it is thought not even to exist. Thus, of someone in the grip of a fatal disease, it is true to say, “He will die of this disease”; but if the same thing is truly said of someone in whom the disease's power is not so apparent, it will happen nonetheless. It follows that even in the future no change from true to false can occur. For “Scipio will die,” though said of the future, has such force that it cannot change into a falsehood: it is said of a human being, who must die.

18 Likewise, if someone had said, “Scipio will die at night in his own bedroom, struck down by violence,” he would have spoken truly. He would have said that something was going to happen which was in fact going to happen; and that it was going to happen must be understood from the fact that it did happen. “Scipio will die” was no truer than “He will die in that way”; it was no more necessary for Scipio to die than to die in that way; “Scipio has been killed” is no more incapable of changing from true to false than “Scipio will be killed.” Since this is so, Epicurus has no reason to dread fate and seek refuge in atoms, diverting them from their course and taking on, at one stroke, two insoluble difficulties. The first is that something should happen without a cause, from which it will follow that something comes from nothing—a view acceptable neither to him nor to any natural philosopher. The second is that, when two indivisible bodies travel through the void, one should move in a straight line and the other swerve.

19 For Epicurus may concede that every statement is either true or false without fearing that everything must therefore happen by fate. The truth of a statement such as “Carneades goes down to the Academy” does not arise from eternal causes flowing from the necessity of nature; yet neither is it without causes. There is a difference between causes that have chanced to precede an event and causes that contain within themselves a natural power to produce it. Thus it was always true that “Epicurus will die after living seventy-two years, in the archonship of Pytharatus.” Yet there were no fated causes why it should happen in that way. Rather, because it did turn out so, it was going to turn out, through a fixed ⟨sequence⟩ of causes, just as it did.

17 Not one of them actually speaks that way. Learning those verbal twists would be harder than learning when the constellations rise and set. Let us return to Diodorus's disputed theory of “possibilities,” which examines what being possible amounts to. He allows possibility only to what is already true or will eventually be true. This connects with the claim that every event had to happen. Whatever is possible is either already the case or will become the case. A true statement concerning a future event cannot become false any more than a true statement concerning a past event can. We can see that the past is fixed. Some future events do not look fixed, so people think they are not. For example, a patient may clearly be dying of a disease. “This disease will kill him” is true. If those same words are true of someone whose disease looks less serious, that person will die just the same. A future truth, then, has no possibility of changing into a falsehood either. Even though “Scipio will die” concerns the future, it cannot become false. It concerns a human being, and human beings must die.

18 Suppose someone said, “Scipio will suffer a violent death during the night in his own bedroom.” The statement would be true: it predicts what would actually happen. The fact that it happened shows that it was going to happen. Saying “Scipio will die” was no truer than specifying that death. Death itself was no more necessary for him than dying in that particular manner. Nor is “Scipio was killed” any less able to change from truth to falsehood than “Scipio will be killed.” With matters standing like this, why should Epicurus fear fate? Why look to atoms for safety, turn them off their course, and accept two problems that cannot be untangled? One is an event with no cause, which leads to something's coming from nothing. Neither Epicurus nor any other natural philosopher accepts that. The other is this: two indivisible bodies move through empty space, yet one continues straight ahead while the other turns aside.

19 Epicurus can accept truth or falsity for every statement without fearing that he must then accept fate for every event. Take “Carneades goes down to the Academy.” Its truth does not come from eternal causes flowing necessarily from nature. It does have causes, however. Causes that happen to come earlier differ from causes with a natural power to produce an effect built into them. Again, the statement “Epicurus will die after seventy-two years of life, with Pytharatus as archon” was true all along. Yet fate supplied no causes requiring that particular death. Rather, since events turned out that way, they were going to turn out that way through a definite ⟨sequence⟩ of causes.