The cognitive arts (such as mnemotechnics, prayer, marketing, rhetoric...) are an underestimated mine of insight for a psychologist (see the AlphaPsy Primer on Cognitive Arts); the rhetoric art of advocacy is a case in point, since it must tap the jury's psychological intuitions about the accused (did he have any rational motive for doing what he's accused of? is he a good guy? etc.) and know quite a bit about the workings of the typical jury member's mind in order to manipulate it. See for example the Corax, a rhetoric argument that taps into our naive theory of what rational actions are:

Suppose that you are a ruthless individual with many enemies and a reputation for violence (we'll call you Vladimir P.); one of your greatest foes has just been killed (let us call her Anna P.). You're in trouble. One possible line of defense for you is the Corax: it consists in arguing that the charges against you are so overwhelming that you can't have murdered Anna P. How could you, since you knew that everyone would think of you as the prime suspect? Knowing all that, you could not reasonably plan a murder, whereas those who had less reasons to kill Anna P., took little risk in doing so, since they knew that all the fingers would point at you at the end of the day.

Greek sophists presented the Corax as a flawed argument, which it is not: it makes perfect sense to assume that one took the consequences of his crime into account before acting, one of the things to be weighed being his reputation and the likeliness of being accused. The sophists want to have us think that the Corax can turn plausibility into implausibility and vice-versa: the more I am suspect, the more I am innocent (this bold allegation earned them much spite from Socrates and Plato). This is only partially true: for the Corax to work, one must not only be suspect, but also be aware, at the time of the crime, that he would be held in suspicion for that crime. This is regular folk-psychological reasoning.

There is a twist, however: the Corax is reversible. Vladimir P. wants us to believe that he cannot have murdered Anna P. because he knew that he would be the prime suspect and could not want to take such a risk. But he could also have anticipated the fact that his being the prime suspect would allow him to defend himself by saying that he could not murder Anna P. because he knew that this would make him the prime suspect. In other words, Vladimir P. could have anticipated the fact that he could use a Corax to disculpate himself (by the way, I think that it's what's really happening with Mr. Putin). Such an argument is what I would call a second-degree Corax. You can destroy it in turn with a third degree Corax (Vladimir P. knew that he could not defend himself by saying that he knew he would be the prime suspect, since he knew that if he did so, the accusation would claim that he knew all along that he would be able to defend himself by saying that he knew all along that everyone would suspect him if he killed Anna P.; hence, Vladimir P; did not kill Anna P.), which is vulnerable to a fourth-degree Corax (OK, I'll spare you with this one), etc.

Surely, Greek rhetoric must have known about second-degree Corax? The astounding answer is : no! In Antiphon's First Tetralogy, the accused is defending himself with what came to be known as the canonical example of Corax. The accusation puts the whole rhetorical apparatus to use in order to make him guilty; some paralogisms are so far-fetched and so subtle that you have to read them four times to grasp the flaw. Most appeal in some way or other to psychological assumptions about the murderer. But second-degree Corax is never resorted to. The teacher, a respected hellenist who wrote a classical Histoire de la littérature grecque, assured me that she had never heard of a second-degree Corax in greek litterature, be it rhetoric or whatever.

There is a debate among game-theorists, philosophers and psychologists on the question of knowing the real depth of our folk psychology (if you do not know what that is, see our little primer). Philosophers have argued that we can perfectly understand up to 7 or 8 embedded propositional attitudes (a propositional attitude is a sentence in the form: he thinks that the sun is bright; embedded propositional attitudes are sentences like: he thinks that she thinks that the sun is bright). However, in the real world, it seems that we very rarely predict or anticipate other people's behavior (their beliefs, in psychology, or their moves, in game theory) up to the third order. Some think it very difficult for a human to compute even second-order anticipations. Our module for predicting beliefs and intentions might not work very smoothly very deep (which it would do if it were, for example, a general recursive mechanism).

The puzzling lack of second-degree Coraxes among greek sophists might point to a limit in our processing the mental states of others.

When I went to see the teacher after the class, she told me it was no wonder why no second-degree Corax was ever produced; a second-degree Corax, she explained, would be exposed to a 3rd-degree Corax, which in turn could be destroyed by a 4th-degree Corax, and so on. She argued that this potential regressio ad infinitum (which she called a sorite - erroneously I think, but this is pure pedantry - in the mood for which I most definitely am); ahem. She argued that this potential regressio ad infinitum amounted to a full-blown counter-argument.

"But" I replied, "This regress argument also applies to the (first-degree) Corax itself, doesn't it?

- Yes it does; that is why the Corax is a paralogism.

- And people realize that when the Corax is 2d-degree or 3d-degree...

- Yes! Isn't that obvious?

- Then how is it that a first-degree Corax works?

She giggled and we left it at that.

That's what's baffling with the Humanities people: they catch a glimpse of amazing things about human nature, then giggle and leave it at that. Most often the psychological consequences of their work does not interest them in the slightest; think only of the progress they could bring to psychology, not by importing our jargon and dogmas into their field (for that is all we can offer them right now), but by mining their own insights into the human mind, taking their conclusions seriously and trying to prove them wrong.

Sigh... there are some things that they, and they alone, could find, that they will never be looking for - while we are looking for things which we may never find.