Cicero’s On Divination

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.