People tend to overestimate the persuasiveness of a message on the part of others but underestimate it on their own part. Sociologists name this dual tendency “the Third Person Effect” and implicate it in various misunderstandings about the influence of mass media. When a person advocates action based on how a message might be received by others, they reveal that they themselves have been implicitly influenced by the message. Social scientists study the Third Person Effect and its impacts on communities, media, and social movements.

The mechanics of the Third Person Effect suggest something morally relevant at work. Beneath the effect lies an implicit assumption of difference between the subject, their interlocutor, and other (third) people. One might believe that that “most people” are less educated, that their perspective is overly informed by a group stereotype, or that some other group-based difference sets the subject apart from the wider audience. Individuals tend to think of themselves as one entity and “everyone else” as an additional entity, failing to recognize that “everyone else” consists of individuals capable of doing the same with regard to themselves. Falling victim to the Third Person Effect reveals an unchecked assumption of inequality and the superiority of the subject.

In Groundwork for the Metaphysics of Morals, Immanuel Kant argues that the principal moral duty, the Categorical Imperative, requires us to treat one another as ends in themselves and never merely as a means. Every person has the rational capacity to interpret the moral law, so all people have equal status as moral agents. A moral agent must be the author of their decisions about duty, the good life, and morality. One then has a duty to assume that others are close reflections of themselves in terms of their epistemic and moral capabilities. The Third Person Effect shows that this duty is often neglected.

Social scientists and epistemologists can agree that the Third Person Effect represents an epistemic error, but ethicists could note a moral error as well. Pragmatically, one must guard against the Third Person Effort, as one must any potential bias in belief or perception. One should also recognize the opportunity for moral reflection, to inquire about the perceived differences driving the Third Person bias in a particular case. Correcting the biases of the Third Person Effect is not just pragmatic, but a moral duty.