We have witnessed an alarming deterioration of truth in democracies around the globe, especially in the political arena. This paper describes a proposed intervention, the Pro-Truth Pledge (PTP), which combines behavioral science research with crowd-sourcing to help address this problem. The PTP asks signers-private citizens and public figures-to commit to 12 behaviors that have been shown to be correlated with an orientation toward truthfulness. Pledge mechanisms have been shown in other contexts to lead private citizens to engage in more pro-social behavior. For public figures, the PTP offers specific incentives to behave in concordance with the Pledge, with rewards in the form of positive reputation for honesty and truth-telling, and accountability through crowd-sourced evaluation and potential aversive consequences contingent upon deception. A study conducted on the PTP has demonstrated its effectiveness in reducing the sharing of misinformation on social media. These preliminary findings suggest that the PTP may be an effective intervention for addressing at least some of the problems caused by fake news and posttruth politics. KEYWORDS: deception, post-truth politics, fake news, alternative facts the worst rating 14.2 percent of the time. Previously, U.S presidential candidates received the worst rating between 10 and 20 percent of the time (Cillizza, 2016). Post-truth politics also describes a new model of behavior when caught lying. Unlike politicians who confess or change position when caught, post-truth politicians do not back away from their falsehoods. Instead, they attack those who point out their deceptions, undermining public trust in credible experts and reliable news sources. This may help explain why trust of the media among Republicans has fallen by more than half, from 32 to 14 percent, from September 2015 to September 2016 (Swift, 2016), as Donald Trump (a Republican) is famous for calling the media "fake news" and suggesting on his Twitter feed that the media distributes "purposely false and defamatory stories" (Huppke, 2017). Fake News and Social Media The pervasiveness of social media has had an exponential impact on spreading non-truths. According to the Pew Research Center, seven out of ten Americans use social media. Twitter, Trump's social media platform of choice, reported 330 million users by the end of 2017 (Statista, 2017). Facebook is the most popular, with 68 percent of U.S. adults using it, and 74 percent of users logging in daily (Pew Research Center, 2018). According to Baum (1994), a large portion of conditioned reinforcers and punishers are social in nature. Thus, social media provides a virtual social community within which behavior may be reinforced or punished by those in one's social network. Arguably, this social network is often more extensive than one's "real life" social network in terms of numbers, in terms of access to each other's lives. Facebook users have more access to the verbal behavior of their Facebook friends than their real life friends, who may go months ...