Under some conditions fact checking can increase fake news

Bayesian Persuasion with Lie Detection. Florian Ederer, Weicheng Min. May 2022. https://florianederer.github.io/lies.pdf

Abstract: How does lie detection constrain the potential for one person to persuade another to change her action? We consider a model of Bayesian persuasion in which the Receiver can detect lies with positive probability. We show that the Sender lies more when the lie detection probability increases. As long as this probability is sufficiently small, the Sender’s and the Receiver’s equilibrium payoffs are unaffected by the presence of lie detection because the Sender simply compensates by lying more. However, when the lie detection probability is sufficiently high, the Sender’s equilibrium payoff decreases and the Receiver’s equilibrium payoff increases with the lie detection probability.