What is up with these wild mode swings by the AI?

[Dinner]

I was allied with four AI, we were attacked by two AI, or rather one of my allies was and I defended the dumb **** as none of my cities were at risk, then without explination or cause three of my allies turned on me, denounced me, and one of them even later declared war on me even as we were still fighting a common enemy and I was still defending them from the aggressor. The only thing I can think of is I lost some units so the AI magically decided I was militarially weak or something so it decided to attack me and denounce me... Even though I was defending the stupid **** from attack. WTF?

This AI is utter crap and Civ4's AI was superior in every way. I might as well be playing with an magic 8 ball because this is just as consistent.

[Lambiorix_be]

Probably they were friends with the civ you attacked. The attacked civ probably asked his friends (your former allies) to denounce you and for whatever price convinced the other one to attack you. Before attacking a civ always look at the different relations between the parties...Nothing to do with mood swings...

[mkorin]

Take off the rose colored glasses. Civ IV was just as stupid with the mood swings. Diplomacy has always sucked with this series.

Mike

[Imran520]

A mood swing is an extreme or rapid change in mood. Such mood swings can play a positive part in promoting problem solving and in producing flexible forward planning.

[Boris Godunov]

The Civ V AI has been designed more to emulate a game player trying to win rather than simulate realistic foreign affairs. So an AI Civ may indeed rapidly turn on another Civ if it thinks doing so will give it an advantage towards winning the game.

Also, if you conquer enemy cities, even ones belonging to a mutual enemy of an ally, your warmonger rating will go up. If your AI ally doesn't tolerate warmongering, they will turn against you.

[lourencohen]

I was not aware...

[Jerieth]

AI behaves illogically all the time.