Decisions now require magistrates, a human resource like EU3's colonists, spies, and merchants. Your country generates magistrates at a rate determined by factors like the number of universities that you've built or the decisions that you've implemented. Regardless of how you get them, they tend to be scarce, which means that you'll often face tough choices like whether to spend all of your magistrates to build a single canal or to build roads in multiple provinces. Don't give too much power to your magistrates, however, or they may try to stage a coup--turning the government into a bureaucratic despotism.