A series of short commentaries on Cicero’s De Divinatione, which he finished around 45 BCE and that comprises two books. The first book features Cicero’s brother, Quintus, presenting the Stoic position on divination, i.e., the art of predicting the future. The second book focuses on Cicero’s criticism of the Stoics. The Stoics were, of course, wrong on this specific issue. Today, we would consider divination a type of pseudoscience. But they were right on the broader epistemological point: if everything happens by cause-effect, that it stands to reason that we should be able to predict the future on the basis of observations in the present. Which is how modern science works.
I.2: Cicero’s brother, Quintus, presents one Stoic argument in favor of divination: everyone knows it’s true. This is an obvious logical fallacy. And yet, there are cases when it is justified to believe a majority opinion.
I.6: Cicero tells us that some Stoics disagreed with the majority opinion within the Stoa on the topic of divination. Indeed, there were multiple opinions on various subjects. Stoicism was never a rigid school of thought.
I.13: Cicero rejects the notion of divination on the grounds that there is no mechanism to explain it. He was wrong on the general epistemological principle, though right in the specific case.
I.23: Cicero’s brother, Quintus, invokes an analogy between a dice game and the structure of the universe to deploy what we today recognize as an argument from intelligent design. Which doesn’t work.
I.24: Cicero’s brother, Quintus, uses a qualitative argument in defense of the notion of divination. The argument appears valid, but it is flawed because of the lack of quantification, which – to be fair – was invented only many centuries later.
I.36: Quintus, Cicero’s brother, puts forth yet another bad argument in favor of divination, one that unfortunately is still used by many today: if celebrity so-and-so says X, then X must be true…
I.62: Quintus, Cicero’s brother, delivers yet another fallacious argument in defense of divination, one that implies that Epicurus got at least one thing right, despite how much Cicero obviously didn’t like him or his philosophy.
I.71: Quintus, Cicero’s brother, relies on other people’s testimony to establish the reality of divination. But as his brother, David Hume, and Carl Sagan observed, that sort of evidence is insufficient to establish his extraordinary claim.
I.110: Cicero makes reference to two problems, as we moderns may see them, with Stoic philosophy: the notion of an intelligence permeating the universe, and the idea that the body is a drag on the mind.
I.122. Quintus, Cicero’s brother, mentions Socrates’ famous daimon as evidence of divine influence. But it is more likely that Socrates himself simply meant the concept as a way to represent his conscience.
I.125: Nothing has happened which was not bound to happen, and, likewise, nothing is going to happen which will not find in nature every efficient cause of its happening.
I.127: Quintus, Cicero’s brother, makes one last – and pretty good – argument in favor of divination, an argument that anticipated a famous idea by the astronomer Pierre-Simon de Laplace.
II.1: Cicero explains the main reason he writes philosophy: to be helpful to other people. But we also know he was helping himself to overcome the grief he felt at the death of his beloved daughter Tullia.
II.8. Cicero is gearing up to respond to his brother’s defense of the Stoic notion of divination. He will do so, however, while putting forth probable arguments, not declarations of certainty. As a good critical thinker ought to do.
II.9-10. Cicero says that nobody actually takes soothsayers seriously, because when we want to actually accomplish something, we go to an expert in that domain, like a doctor, and not a to a seer or a prophet.
II.17: Science, argues Cicero, makes reliable predictions of events based on the laws of nature. No such reliability is possible for mysticisms like divination.
II.27: You ought to have employed arguments and reason to show that all your propositions were true and you ought not to have resorted to so-called occurrences — certainly not to such occurrences as are unworthy of belief.
II.28: How did the soothsayers manage to agree among themselves what part of the entrails was unfavourable, and what part favourable; or what cleft in the liver indicated danger and what promised some advantage?
II.37: Don’t you think, rather, that the bull lost his heart when he saw that Caesar, in his purple robe, had lost his head?
II.37: Upon my word you Stoics surrender the very city of philosophy while defending its outworks! For, by your insistence on the truth of soothsaying, you utterly overthrow physiology.
II.47: You say, ‘Jupiter’s statue was being set up at the very time the conspiracy was being exposed.’ You, of course, prefer to attribute this coincidence to a divine decree rather than to chance.
II.52: While Hannibal was in exile at the court of King Prusias he advised the king to go to war, but the king replied, ‘I do not dare, because the entrails forbid.’ ‘And do you,’ said Hannibal, ‘put more reliance in a piece of ox-meat than you do in a veteran commander?’
II.55: In the case of things that happen now by chance, now in the usual course of nature, it is the height of folly to hold the gods as the direct agents and not to inquire into the causes of such things.
II.58: In periods of fear and of danger, stories of portents are not only more readily believed, but they are invented with greater impunity.
II.60: Explore the cause, if you can, of every strange thing that excites your astonishment. If you do not find the cause be assured, nevertheless, that nothing could have happened without a cause.
II.66: The incidents may have been fictitious; if not, then the fulfillment of the prophecy may have been accidental.
II.71: ‘Flaminius,’ you say, ‘did not obey the auspices, therefore he perished with his army.’ But a year later Paulus did obey them; and did he not lose his army and his life in the battle of Cannae?
II.80: Myths would have no place in philosophy. It would have been more in keeping with your role as a philosopher to consider, first, the nature of divination generally, second, its origin, and third, its consistency.
II.92: Is it not evident that these astrologers, these would-be interpreters of the sky are of a class who are utterly ignorant of the nature of the sky?
II.94: Surely, no one fails to see that the appearance and habits, and generally, the carriage and gestures of children are derived from their parents, not by the phases of the moon and by the condition of the sky.
II.110-111: It was clever in the author to take care that whatever happened should appear foretold because all reference to persons or time had been omitted.
II.121: We sleep every night and there is scarcely ever a night when we do not dream; then do we wonder that our dreams come true sometimes?
II.129: Which is more consonant with philosophy: to explain these apparitions by the superstitious theories of fortune-telling hags, or by an explanation based on natural causes?
II.148: Speaking frankly, superstition, which is widespread among the nations, has taken advantage of human weakness to cast its spell over the mind of almost every man.