Hate Speech in the Marketplace of Ideas

In this paper, I consider the issue of restrictions on hate speech in the context of the argument for free expression based on the idea that the realm of public communication is a "marketplace of ideas." What is the nature of the analogy with the economic marketplace implied by this phrase? Can maximizing the prospects for attaining truth in the realm of public communication (if this is its proper goal) be fruitfully compared with maximizing preference satisfaction in the economic market? And, does the analogy prove too much, in that arguments for government interference in economic markets based on the existence of "market imperfections" might he taken to justify analogous interference in the case of speech? Can hate speech be understood as analogous to a market imperfection?