It is nicely explained in thread which Joe provided, but if you need example here we go.
Starting game as Monarchy (standard not Const. Monarchy) with Plurality ~0%. Militancy is 0% (unless you starting with some country in the middle of rebellion - Morocco or something like that). Consciousness for overwhelming majority of population is also 0. All is nice. Peaceful.
As game progressing Plurality, consciousness, militancy going up/down depending on a country, POPs % split, ideology, events, religion, wars, goods availability, conquered nations, unemployment. In one sentence: Hundred of issues.
If Plurality reach 40+% and you are still a Monarchy be prepared for tough time ahead of you. Revolts will spread fairly quickly. IMHO 40% is line when you must switch to Const. Monarchy or Democracy (depending on a country).
MIL, CON and PLU are connected. Higher PLU = higher CON = higher MIL if form of goverment is not popular, you banned a party, country is exhausted with war. But on the other hand high PLU + high CON = reduced MIL for conquered regions - if you are Democratic country.
To sum up: Vicky/Ricky is so complicated that it is impossible to give simple answer, because every time - in the end - you reach golden sentence "It depend on a ...".
