“Post-truth” politics is often framed as a failure of the competition of ideas. Yet there are different ways of thinking about the competition of ideas, with different implications for the way we understand its benefits and risks. The dominant way of framing the competition of ideas is in terms of a marketplace, which, however, obscures the different ways ideas can compete. Several theorists can help us think through the competition of ideas. J. S. Mill, for example, avoided the metaphor of the market by focusing, instead, on competition as the testing of arguments in adversarial encounters before a critical audience. Georg Simmel, alternatively, conceived of competition as a form of indirect conflict, where two individuals strive in parallel to gain audience approval. This view emphasizes innovation and creativity in the competition of “all for all.” More recently, theorists have developed the market logic of competition by thinking of a marketplace not for ideas but for rationalizations. This articulates some of the features of Simmel’s view of competition, but underestimates the degrees of constraint required to secure the goods of competition. Ultimately, recognizing these different modes of competition in the public sphere can enrich our theories of deliberative democracy and sharpen our view of the problem of “post-truth” politics.