Yeah; Grandgnu you are correct which is why I used an example of a cash game. Tournaments require a different way of playing; that takes into account self-preservation for future rounds. However cash games are different.

Skrum: "It may take a lot of work to show that someone is rational but you don't have to be very bright to show that someone is irrational. If it is in fact true that it is irrational not to go all in if you have pocket aces, and I observe that someone has pocket aces (I have watched a few episodes of World Series of Poker where the viewers can see the player's pocket cards as he picks them up) and that player does not go all-in, then I, even with my minimal knowledge of the game, know that the player has acted irrationally."

Well that isn't completely true either. If you have pocket aces in a cash game; it is always rational to CALL an all-in pre-flop. However it is not always rational to RAISE all-in. It could have the effect of scaring everyone away pre-flop before you build a pot; and thus wasting your pocket aces.

Skrum: "In the policeman example, I am not sure whether you are asking about whether the shooting was rational or whether his having said he shot the man was rational, but there is a TV program called 'America's Dumbest Criminals.'"

Well I'll let you choose which one you want to answer. In my opinion; it is impossible to tell the rationality of either action without knowing the CAUSE of the action.

Unfortunately I am unable to read your study, Skrum, because it is requiring a paid subscription. However from the description it doesn't sound like they are claiming the ability to judge rationality based on the EFFECT of a trade. In fact; it even seems to imply that they might be using information from the traders themselves (CAUSES) in their calculations; but I'm not sure without reading it.

Btw; the poker example is a gift; because it is actually possible to declare with certainty the irrationality of some actions. However in real life scenarios where there aren't a set of very restrictive rules; it is nearly impossible to do so.

Take my police example from above; or create your own and we can go into more detail.

Here is the complete pdf of the paper from a different site.

Section 3.1 shows how the irrationality of a trade is ascertained.

In regard to confession of a crime, the law has a doctrine called "statement against interest." Normally, hearsay evidence of the truth of something that has been said by someone else, not the witness, is not admissible in court. But if the statement creates a hazard against the speaker, the presumption (which is rebuttable) is formed that the speaker is telling the truth and the statement is admissible in court.

I forgot to give the cite:

http://www.biz.uiowa.edu/faculty/trietz/papers/arbitrage.pdf

I think you forgot the link.

As for the police scenario; I'm not totally sure why the truthfulness is relevant here. Let's pretend that all the things stated are facts; and the man DID shoot the other man. It isn't a question of whether or not he is telling the truth. It is a question of whether the shooting was a rational action or not.

It is my position that you cannot judge the rationality of the action without knowing the cause of the action. In this scenario; the policeman represents you; and he is being asked whether the shooter acted rationally or not. All he knows is that the shooting took place and the man has in fact shot the other man.

Okay thanks for the link; let me take my time to digest it.

Law presumes rationality. The plaintiff/prosecutor doesn't have to show it. Lack of rationality is not a defense, unless you want to show that the defendent was incapable of acting rationally, that is, that he was insane. Showing insanity is the burden of the defense.

All law is evidential. To be introduced into evidence, something has to have been observed. Any opinion entered on the record has to relate to the evidence.

This is kinda frustrating; because you have shifted the topic to law; when we obviously weren't talking about that.