Arathorn said:

Culture flips can be entirely prevented, through a number of mechanisms (raze and replace, no pressing builds, enough military units). Rebellions can never be eliminated, according to this proposal. Culture flips are limited to a select few locations -- rebellions would be anywhere. These are major differences.
Sorry, I should have know I wasn't saying that very well. The problem with culture flips isn't that the
occurrence of them is random: you're quite correct that there are many things you can do to prevent them (although Dell19 is also correct that some of those things aren't exactly fun to have to do). The main problem, though, is that you can't do anything to
deal with them once they happen (short of conquering the city back), so a random event winds up having a very jarring and disruptive effect. Contrast that with an invasion by a foreign civ. Vesuvius_prime just claimed that's also governed by a random "dice-roll" - I don't know if it is or isn't, but I do know that its quite difficult to predict exactly when and where a rival might attack, so it "feels" random whether it is or isn't . When another civ sends a stack of units your way or declares war on you, there are plenty of ways you can respond: various military strategies, diplomatic efforts to bribe the enemy for peace or bribe third parties to join the war on your side, etc. You have plenty chance to respond before the enemy overruns your cities. When a city flips to another civ, its gone. Very suddenly, with no chance to respond, you've lost an entire city. So the
feeling is very different. A military campaign is full of the occurrence of random numbers (and, if vesiuvius_prime is correct, can also start based on a random number) and its quite possible that a single lucky or unlucky roll can make or break the sucess of such a campaign. But you seldom get the same feeling you get when a city suddenly and seemingly randomly converts to another civ (and all your units there vanish without a trace). The feeling of "What the?!?!? That was stupid!"
Culture flips can occur anywhere between 0 and probably 60-70 times a game, with a mean of around 2 or so. To be an effective constraint on expansion, rebellions will have to occur a lot more frequently and/or be a lot more devastating than culture flips. If people hate culture flips (and the general consensus I've seen even in this thread is that they're no fun), what will they think of rebellions?
An invasion by a strong rival army has the potential to be far more devastating that a culture flip, and yet even when it is, it doesn't generate the same feeling of "that's not fair" that a sudden and seemingly arbitrary culture flip does. Its also possible for a foreign invasion to be quite ineffective, if you're well prepared for it. And thus its quite possible to make it through entire games without ever being subjected to a devastating foreign invasion. Yet the fact that a rival
could invade you influences your strategy in every game, to a very large degree. You build offensive and defensive units, grab resources, sign agreements, sometimes preemptively invade rivals, all because the
threat of foreign invasion exists and the consequences are
potentially devastating. The devastation doesn't actually have to occur for the threat to influence your strategy. In other words, the degree to which some type of event can influence your gameplay is not necessarily directly in proportion to the frequency with which it typically occurs, nor the devastation it typical brings... the devastation it could
potentially bring and the frequencu with which it could
potentially occur can matter a lot more. If you never built any military units, I'm sure devastating foreign invasions would occur in every single game.
Its the same thing with culture flipping: that also influences your strategy much more through its
threat than its actual occurence (at least for experienced players who have figured out what it takes to prevent flips). However, the strategies that you are pressured to adopt (i.e., razing or starving down captured cities, stationing obscene numbers of units in vulnerable cities, and rushing the building of libraries and temples during the middle of a war) don't feel particularly interesting or fun. In other words, the randomness of culture flips is problematic because minimizing or eliminating the odds of a flip doesn't involve fun strategy, but if you don't do it, there's no other way to blunt the effect: the flip happens suddenly and jarringly and gives you no chance to respond.
The point of all of this is that rebellions should work much more like foreign invasions (in certain regards) than like culture flips. The
threat of them occurring should have an impact on your gameplay: slowing your expansion, causing you to pay more attention to people's happiness, what nationality they're from, how much culture you've built up, etc. If you play in a certain way, the actual
occurrence of rebellions would be relatively rare, just like the likelihood of foreign invasion can be minimized (but never eliminated) by making sure you have a sizeable defensive military force. And if you were well prepared for it, the devastation due to rebellion wouldn't be very bad either, just like being well prepared for a foreign invasion can drastically affect how serious the invasion is.
I also think some of us are drawing false correlations. The purpose of culture flips was to provide balance, yes, but it was to provide balance between "guns" and "butter" -- that is, to give builders a type of defense/offense against pure militarists.
Agreed- rebellions are meant to provide anti-snowball effect (civ vs. civ balance) by replacing corruption & waste, not culture flipping. I merely wanted to point out that they could
also replace culture flipping (which, you're quite correct, is an issue of guns vs. butter balance, not civ vs. civ balance). If rebellions were implemented in such a way that they didn't occur as
suddenly and
completely as culture flips, and if the things you could do to minimize the occurrence felt more like fun strategies rather than the somewhat silly things you need to do to prevent culture flips, then I think they could be an improvement compared to culture flips.
My main point is that any randomness is too much. And no randomness doesn't work either. If the player has complete control, rebellions won't really serve to check expansion. If there's any randomness, one die roll (which it has to come done to, if there's any randomness at all) will have a profound effect on the game -- much moreso than one of the hundreds of rolls in military operations. And I don't particularly like my game being decided by one roll.
It all depends on
how rebellions are implemented. If part of your empire randomly and suddenly isn't yours anymore, then I agree, it would be like culture flipping, only worse, and way too much would hang on a single random number. My preferred solution would be to have potentially rebellious cities first slip into disorder/resistance, which you would have a chance to fix before things got further out of hand. If they were in disorder too long, they would begin drafting hostile "rebel" units, but you'd still have a chance to defeat those units and crush the rebellion before actually losing a city or cities. Only if the rebellious units successfully defeated your loyal units would they be able to declare a city to be part of a new (or existing foreign) country.
With such a system, no single random dice-roll has too profound an effect on the game. In order for a rebellion to be successful, a string of many dice-rolls must go against you, and the strategy with which you play would directly influence the odds in each of those rolls. You could expand slowly, making sure to thouroughly consolidate all your gains, in order to minimize the number of potentially rebellious cities in the first place. Or you could expand more quickly but take along plenty of extra units in order to quickly put down potential rebellions before you lose any cities. How you choose to minimize the chances of rebellion would be up to the individual player, but hopefully, the viable options would be more interesting than the strategies available currently for preventing culture flips (although, admittedly, some of the strategies might be quite similar). And any of the options (building more cultural buildings, building more military units, playing with the luxury slder, etc.) would serve to reduce the rate at which you expanded, and thus they would have an anti-snowball effect.
To sum up: Its the
threat of something happening, and the
potential devastation involved, that influence your strategy, not the actual frequency of occurence or typical level of impact. And if implemented properly, the threat of rebellions would influence your strategy in more interesting ways than the threat of culture flips and the reality of rampant corruption/waste in outlying cities. Thus, hopefully, rebellions could have the same "balancing" effect (both civ vs. civ and guns vs. butter) as flips and corruption, while presenting more interesting strategies for coping.