Gelman’s characterization of his opposition is more than a little reductive.

Gelman’s characterization of his opposition is more than a little reductive. In brownian motion, the particles are wholly passive. However, the varieties of stimuli that are being studied with respect to their effect on human behavior are, in fact, primarily human-produced and can be modeled as a form of communication wherein ideas are spread subtly without analysis. It’s not controversial that this kind of communication (and this kind of spread) occurs within media, wherein we have dated archives showing various elements (arguably without rational basis) growing and shrinking in popularity in accordance with power laws; why should we believe that people do not communicate this way when they are not being recorded, or when they are outside the silos of media production?