Trust is essential to holding society together, but increasingly we only trust people like us. We make our judgments about what is true based on our affinity with those who say it. As President Barack Obama warned in his farewell speech, we "retreat into our own bubbles, whether in our neighborhoods or on college campuses, or places of worship, or especially our social media feeds, surrounded by people who look like us and share the same political outlook and never challenge our assumptions. ... (W)e become so secure in our bubbles that we start accepting only information, whether it's true or not, that fits our opinions, instead of basing our opinions on the evidence that is out there."