Abstract
The fog of war—poor intelligence about the enemy—can frustrate even a well-prepared military force. Something similar can happen in intellectual debate. What I call the *fog of debate* is a useful metaphor for grappling with failures and dysfunctions of argumentative persuasion that stem from poor information about our opponents. It is distressingly easy to make mistakes about our opponents’ thinking, as well as to fail to comprehend their understanding of and reactions to our arguments. After describing the fog of debate and outlining its sources in cognition and communication, I consider a few policies we might adopt upon learning we are in this fog.