Interpersonal communication is sometimes defined quantitatively (i.e., discourse between 2 and 4 interactants), though it may be defined qualitatively: Unlike mass-mediated communication, which is characterized by interactant anonymity and interchangeability, interpersonal communication hinges on the once-occurrence and noninterchangeability—the existential particularity—of interactants and interaction. Accordingly, this article advances a communicological orientation toward interpersonal communication by focusing on those aspects and dimensions of communication that critically depend on the once-occurrence and noninterchangeability of interactants and their interaction. I begin by exploring some main obstacles to recognizing particularity. Next, I examine how agency and efficacy in interpersonal communication amount to reckoning with once-occurrence and noninterchangeability. Finally, I illustrate the vitality of particularity in two domains of interpersonal communication: face-to-face conversation and family bonds.

Whether our theories comprehend the facts or not would seem to be of lesser moment than that they be simple enough for us to comprehend. Lee Thayer (1987, p. 227)

In Greece, just as in philosophy's youth on the whole, the difficulty was to attain the abstract, to abandon existence, which continually yields the particular; now there is the opposite difficulty, to attain existence. Soren Kierkegaard (1992, p. 331)