Noisy Speech Externalities


A central tenet of contemporary First Amendment law is the metaphor of the marketplace of ideas—that the solution to bad speech is more, better, speech. This basic idea is well-established in both judicial and scholarly writing—but it is not without its critics. My contribution to this volume adds a new criticism of the marketplace-of-ideas metaphor. I argue that there are circumstances where ostensibly “good” speech may be indistinguishable by listeners from bad speech—indeed, that there are cases in which any incremental speech can actually make other good speech indistinguishable from bad speech. In such cases, seemingly “good” speech has the effect of “bad” speech. I call this process by which ostensibly good speech turns the effects of other speech bad “a noisy speech externality.”

This thesis has important implications. First, it offers a poignant critique of the marketplace-of-ideas aphorism introduced by Justice Holmes in his Abrams dissent. If the marketplace of ideas is subject to significant market failure, correctives may be justified. Market failures, after all, are a standard justification for regulatory intervention. But, second, my contribution goes a step farther, suggesting not only that there are circumstances in which good speech may fail as a corrective to bad speech but also that there are circumstances in which the addition of seemingly good speech may only yield more bad speech. In such cases, the only solution to bad speech may be less speech—encouraging more speech may actually be detrimental to our speech values. If that is the case, then correctives may be not only justified but needed to satisfy an important societal interest. And, third, this chapter presents solutions for content-neutral ways in which to implement such correctives.

The insight underlying this thesis builds on my prior work applying the insights of Claude Shannon’s information theory to social media. That piece applied Shannon’s work to social media to argue that, at least at a metaphorical level and potentially at a cognitive level, our capacity to communicate is governed by Shannon’s channel-capacity theorem. This theorem tells us that the capacity of a communications channel is limited by that channel’s signal-to-noise ratio. Critically, once that capacity is exceeded, any additional signal is indistinguishable from noise—and this has the effect of worsening the signal-to-noise ratio, further reducing the communications capacity. In other words, after a certain threshold, additional speech isn’t merely ineffective: It creates a negative externality that interferes with other speech.

Other scholars have made similar arguments, which can casually be framed as exploring the effects of “too much information” or “information overload.” But the negative-externality element of this argument goes a step further. A “too much information” argument suggests that listeners are overwhelmed by the quantity of speech to which they may be subject. This argument suggests that speakers can—deliberately or otherwise—exercise a veto over other speakers by saturating listeners’ information sources. For the listener, it is not merely a question of filtering out the good information from the bad (the signal from the noise): At the point of saturation, signal cannot be differentiated from noise and any filtering necessarily must occur upstream from the listener.

Filtering—reducing the overall amount of speech—has always been a key tool in fighting bad speech. All platforms must filter. Indeed, this is nothing new: Editorial processes have always been valuable to listeners. The question is how they do it, with a related question of the law surrounding that filtering. Under the current approach (facilitated through Section 230 of the Communications Decency Act and built upon First Amendment principles), platforms have substantial discretion over what speech they host. This chapter’s normative contribution is to argue that liability shield should be contingent upon platforms using “reasonable best-available technology” to filter speech—a standard that most platforms, this chapter also argues, likely already meet.

The discussion in this chapter proceeds in four parts. It begins in Part I by introducing technical concepts from the field of information theory—most notably the ideas of channel capacity and the role of the signal-to-noise ratio in defining a channel’s capacity. Part II then introduces the traditional “marketplace of ideas” understanding of the First Amendment and builds on lessons from information theory to argue that this “marketplace” may in some cases be subject to negative externalities—noisy speech externalities—and that such externalities may justify some forms of corrective regulation. It also considers other arguments that have a similar feeling (“too much information,” “information overload,” and “listeners’ rights”), and explains how the negative-externalities consequence of exceeding a channel’s carrying capacity presents an even greater concern than is advanced by those ideas. Parts III and IV then explore the First Amendment and regulatory responses to these concerns, arguing that the negative-externalities concern might justify limited regulatory response. In particular, Part IV argues that platforms can reasonably be expected to implement “reasonable best available technologies” to address noisy speech externalities.