Ok, have patience my son, this is a complicated subject...
When I wrote the first and second editions of the manual, I was basically copying Carligula's essay, but I think I have the subject down a bit better now.
Consciousness the numerical representation of how well a POP understands its own politics. The higher the consciousness, the more they understand their own political needs and desires. This is not necessarily a bad thing. If you have a largely conservative population and a conservative government (Russia), consciousness has positive effects. Conservative POPs with high consciousness are only realizing that they are conservative, so they'll like the conservative government. Institute a liberal government, however, and watch the high consciousness conservative POPs rebel like mad. The opposite, of course, is also true. If you have a largely liberal population and a liberal government, high consciousness will have no negative effects either.
The problem comes when you have a divided population. Look at Austria for an example. By the 1880, even a well managed Austria will tend to have a large liberal minority. Since Austria will likely still have a conservative government, and its POPs will have mid to high levels of consciousness, that liberal minority, as it realizes the government does not suit it, will have its militancy increase rapidly as a result. This next point is key: if the POPs have very low consciousness, you can pass off any government on them. Think about it. If you had a 90% liberal population, you could never have a conservative government--unless those people didn't know that they were liberal. And that's exactly what consciousness is--the numerical representation of how well POPs understand their own politics.
Thence comes the connection between consciousness and militancy--if you have a divided population (as most countries eventually do), then the only way to keep the minority ideology content is to keep them from knowing that they are any different from the majority, which means keeping their consciousness low. Sure, you can pass reforms and lower taxes and such, but those are really only band aids to cover wounds that have already been made. Keeping consciousness low keeps the wound from ever forming at all.
Plurality is the numerical representation of your society's demand for a democratic government. The higher the plurality percentage, the more your country wants to be a democracy, and the less content they are not being a democracy. Just like consciousness, plurality affects militancy, but unlike consciousness, the effect varies by the form of government. In monarchies, plurality increases militancy because the monarchy is undemocratic; in constitutional monarchies plurality doesn’t affect militancy at all, because at least in game terms, constitutional monarchies are just as monarchical as democratic, so it evens out; in democracies, plurality reduces militancy, because the people are getting exactly what they want. In simpler terms, plurality in monarchies is bad, plurality in constitutional monarchies doesn’t matter, and plurality in democracies is good.
This is different from consciousness specifically because it has nothing to do with POP ideologies. In theory, a country could have 100% plurality and also be 100% conservative—but only if that country were a democracy. Think about it. If a country had a very high plurality, its people would want to be a democracy. If that country were also 100% conservative, they would just elect a conservative party, and that would be that. If, on the other hand, a country with 100% plurality were a monarchy, the militancy would be off the charts, and the POPs would begin to convert to reactionaries and Anarcho-liberals and other nasty kinds of people.
Hopefully that made sense. Please, if it didn’t, tell me what was confusing and I’ll explain.
Regards,
Memnon