Diplomacy is in urgent need of help

[Becephalus]

I just won a China Science/Cultural/Diplomatic Victory (would have finished all within 10 turns of each other) on Emporer where no one fought me after the middle ages.

France declared war (i am sure because of my small army) in ancient fought him off.
I had 6 cities, caesar declared war in classical (once again for small army), I puppeted one of his towns and left him the rest.
Egypt declared on me 3 times in the middle ages (all for my small army) took one of his in the last war.

So near in the second half of the game I had 8 cities, a smallish if advanced army, and no friends, yet I traded with everyone and no one disliked me.

If you don't want to be attack don't take over too many cities, don't kill civs/CSs, don't make friends with people. It is very easy to play peacefully if you choose to do so.

 

[Lance of Llanwy]

I think the AI definitely needs to react in a more contextual manner in regards to war-mongering. For example...
1) A small number of civs should have the current attitude, whereby any and all aggression is not to be tolerated. They should probably be active in trying to round up friends to help reign the aggressor in, or, at least, protect themselves. Example civs- India, Siam

2)A paternal attitude. These civs probably really wouldn't care very much if you just took a few cities or conquered a CS they didn't care about. But, if they have a vested interest in the matter, they get extremely belligerent towards you(assuming they have at least a comparable military). This would probably be most engaging if there was some sort of system of spheres, but it could still work otherwise. Example civs- China, America

3) An entirely indifferent attitude. Just can't be bothered by whatever it is you're doing as long as you just leave them to their own devices. Example civs- Egypt?(I don't recall him minding much other than you building wonders he wants)

4) A celebratory attitude. They think it's pretty cool that you've carved out such a sweet empire (for them). Example civs: Mongols, Aztec

Of course, civs should be able to display other attitudes, depending on a variety of factors(are you their friend or enemy, how powerful they are in relation to you, etc.)

 

[Simplicity4]

What drives me crazy about the AI is the fickleness of it. Long term relations don't seem to have any effect. I was friends with Napolean for half a game. Helped in a wars. All of a sudden, blam. Betrayal. Fine. That part is totally fine. After a heated war than lasted forever, and after I stripped him of a couple of cities, we get peace. And BAM we're BFFs again. REALLY? None of that war actually mattered?