This piece by Moshe Arens on the appointment of Avigdor Lieberman as minister for strategic thinking about Iran is well worth a read:

[A]s we know the irrational player, the "crazy one," has certain advantages in such a situation. Ever since John von Neumann pioneered the game theory, the study of the interaction between parties having conflicting interests, the difficulties of dealing with a non-rational player have been clearly recognized.

...But when a rational player confronts an irrational one, the irrational player has a decided advantage. While he is counting on the rational response of his opponents to his moves, they don't know what to expect of him. Maybe their best bet is just to let him have what he wants, rather than risking his irrational response to their move. Given the reticence of the U.S. and European nations in facing up to the bellicose, adventurous leaders of Iran and North Korea pursuing their nuclear ambitions, one begins to wonder whether they have not decided to revert to such a strategy. Maybe it is better to be at least temporarily safe than sorry.

But what if the irrational player is confronted by an irrational opponent? Now here is a brain-buster. And maybe this is what Olmert had in mind. Let Lieberman act the role of the irrational player, and now let's see what Ahmadinejad will do. Maybe this is the way to outwit the madman in Teheran. Lieberman's past statements about bombing Teheran, destroying the Aswan dam, laying waste to Gaza, and stripping Israel's Arab citizens of their citizenship might very well make Ahmedinejad believe that now he is up against an entirely different type of opponent.