The design and implementation of social media platforms has put several advanced democracies into a kind of democratic deficit. First, social algorithms allow fake news stories from untrustworthy sources to spread like wildfire over networks of family and friends. Second, social media algorithms provide very real structure to what political scientists often call “elective affinity” or “selective exposure”. We prefer to strengthen our ties to the people and organizations we already know and like. Third, technology companies, including Facebook and Twitter, have been given a moral pass on the normative obligations for democratic discourse that we hold journalists and civil society groups to. Using evidence from the ERC-funded Consolidator Award on Computational Propaganda (COMPROP, www.politicalbots.org), I discuss the ways in which social media platforms have become they key infrastructures for political discourse, identify how these technological affordances have put us into a democratic deficit, and conclude with some ideas about ways in which social media platforms could be a better infrastructure for deliberative democracy.