Before I reply to the many excellent points brought up here, I have to applaud you all: for once I have proposed an idea and the criticism against it was not that it's too complicated, but rather that certain complexities are missing in it. You're right and I'm right, but to save myself some double typing, I'll explain the logic behind the system as I described it.
The basic idea is that other than the "constant" modifiers (trade and Civics), events are the only thing that matters. No gradual shifts, no synergistic properties of simple factors, just events. This is inaccurate historically but necessary from the perspectives of design and gameplay.
For design, the system has to be simple and require as few checks as possible for it to work. In fact, the way I see it, the whole thing could be done without a single check bogging down The Fastest Mod. Everything can be done by adding new code onto existing events.
For gameplay - and this is the most important point - the way it's supposed to work is that your behavior as a player is the most important thing, and graduality is achieved by having a whole lot of small factors that happen relatively often, to make the rating fluctuate all over the place, the general trend being determined by proportions. I know this is abstract, so I'll go into more detail in replying to specific comments.
I would have thought culture might play a role in determining stability -- for example, if many of your cities have a minority of your own culture, you would be less stable.
You're right, but this would require extra checks and I don't want the mod to run any slower just for Stability. Cities with higher controller nationality will naturally have a good effect on Stability in the long run, since the buildings and units you build for the city over time will add to Stability...
I was just wondering...
Lets say I'm Universal suffrage, free speech, Emancipation, Environmentalism, Free religion (all the "I'm the nicest guy in the world" civics). I understand that under any war, this is probably the worst combination for stability. You'll get unrest, protests etc. But with peace, souldn't this combination be more stable than say, Police State and the likes?
...
All in all, I wanted to suggest the (added complication) of a peace stability rating and a war stability rating for every civic. In my view, any democratic nation is far more stable than a dictatorship in peace times.
You're generally right, but I'd like to point out an important point on scale: in-game Wars are not exactly what we call a war in real life... Most real life wars take much less than a single turn's time. Civ's Wars are actually periods of open hostility between nations. As such, being in a War should not have a direct effect on Stability. In my current game as first-place (by score) Germany I'm at war with the last-place India who is nowhere nearby my borders. None of my units have seen India or any of her units in centuries (since I first discovered India way back when.) In other words, not every War would have the effect that wars have had on the stability of nations.
This is why the Stability system as I describe it has the kind of things that happen in an active war destabilizing you, and the kind of thing you mainly do in peace-time stabilizing you. If you have mainly war-time Civics (anywhere but Religion) you can take the initial blow of not doing well at the start of a war (which happens in-game even to the best human players sometimes). If you have peace-time civics in a bad war you have to maintain peace-time activity to keep your Stability safe, and even then you will be hard-pressed to keep it all together...
In other words, you have to realize that there is some synergy between the constant factors and the event factors. Having a revolution to peace-time Civics will be a major hit to your Stability unless Pacifism is in there, so if you don't do it after some peace and stabilization or at least directly follow it with active stabilization, it will lead to problems.
I think overall your choice of Civics will always have only a temporary effect on Stability since even a completely BAMF war-time government can't last forever when it's obviously losing a war. And the destabilization of a Nice Guy liberal government will go away over time as you use those Civics' bonuses to get new techs, new building, new units, etc.
On another issue, I fear the multiplicity of stability bonus/malus will confuse a lot of person as what should be done to higher your stability rating. I don't think it should be simplified (god forbid

), but maybe add some hints in the Sid tips boxes that appear when your mouse is over a building name. Or add bonus and malus hints when the pop up for conquering/founding a city appears. Even have bonus/malus messages in the event log : "Rome built a courthouse. Roman stability increases a bit" "Russia declares war on Mongolia. Mongolian stability decreases moderatly." and so on. Otherwise, many people will be at a loss when they see their stability rating and ask themselves "Why am I still so unstable after all I did?".
The whole idea is that you aren't aware of the tiny factors in play. You only get notified when you go up or down a Stability "level", so you can tell how you're doing but you aren't flooded with a million messages on the fluctuations. A late-game turn will probably have around ten events per turn factoring in on Stability, it would be a mess to see each one of them. Maybe the really big factors can have their own messages ("Peace with the Turks, finally! Our people are more quiet now."; "Moskau III founded - this new city has given some of our people hope and made them like us more!"
*). Another way to keep players in the loop could be to have the Domestic Advisor mention what you should generally do to maintain Sability. "Prime Minister, our nation is now Disintegrating! We have to increase Stability or this government is toast! Peacefully building up your empire should do the trick."
*Moskau III is a city I recently founded in my current game. The story runs as such: Russia declared war on me, I brought Greece in as an ally, and before I could get there first the Greeks razed Moskva. Ages later I founded a new city in the same excellent tile, naming it Moskau II (Moskau is German for Moscow). A few turns later, Greece with its vassals - Russia among them - declared war on me and razed Moskau II. Then once I got my act together and reconquered Eastern Europe about fifteen turns later, I razed Nizhnij Novgorod (which was two tiles east of Moscow) and erected Moskau III.
I hope I have answered this point already in the things I have written in this post. If not, please say so and I will try to better explain myself.
Also, perhaps we could create a 'stability' screen in the foreign advisor screen that can give summaries of you and your rival's stability, similar to how it gives summaries of you and your rival's diplomatic relations.
This would be nice for serious gamers, but right now I think this should not have a high priority just yet.
The civics screen could give you a preview of the new stability factor with currently chosen civics. This would give the player a chance to mix civics for max stability before actually changing them (in case that is the primary concern of the player).
I agree, only I think it should say nothing but the final Stability "level" nickname, to avoid confusing newer players with details.
I'm making some small changes to The Crunch because of little thought that have occurred to me. Nothing major right now.