Once you reach the Modern Age in you'll have the choice to focus on three distinct ideologies: Democracy, Fascism, and Communism. Each has their unique benefits, and choosing a particular Ideology will have implications with other leaders in the campaign. Your choice of Ideology can depend on a number of factors and will largely be based on what strategy or Legacy Paths you plan on pursuing toward an eventual victory. Each Ideology unlocks certain effects and social policies that are catered around two particular resources, and has a total of three Civics associated with it.
To unlock the Ideology Civic Trees, you first have to unlock the initial Modern Age Civics, Social Question, Modernization, and Natural History, then complete the Political Theory Civic. You'll then have the choice to study one of the three Ideology paths and are locked into that decision for the remainder of the game. Once you've committed to an ideology, opponents will also have the option to choose an Ideology, and if you're pursuing a Military Victory, you'll want to wage war against someone following one of the other two Ideologies that you didn't choose.
The Democracy Civic instantly awards you four infantry units and both a Cultural and Diplomatic Attribute point. It will also unlock the Fireside Chats and Suffrage Social Policies. Fireside Chats gives you +4 Happiness from Specialists at the cost of -3 Gold in all Towns, while Suffrage gives you +3 Culture from Specialists at the cost of -3 Production in Towns.
Democracy opens up Liberalism and then the Progressivism Civics, which both unlock further social policies. This Ideology is ideal for a Cultural Victory, at least in theory — based on the way the Cultural Victory works, Culture isn't actually an essential resource in the Modern Age.
Production in Towns is converted to Gold, so both the Suffrage and Fireside Chats social policies will impact the treasury.
One useful social policy unlocked in Progressivism is the New Deal, as it in
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