Is Reference a Relation of Equivalence or Sameness?

The stimulus equivalence (SE) paradigm has become a central explanatory framework for language and complex symbolic behavior within behavior analysis. Its explanatory power rests on three core assumptions: (1) human symbolic behavior is grounded in the semantic relation between words and their referents; (2) this relation is one of equivalence; and in consequence (3) there is a transfer of stimulus functions between words and their referents. These assumptions are also endorsed by relational frame theory (RFT), although considering equivalence as a consequence of a relation of sameness within a relational frame of coordination. However, this article shows that the referential relation is neither reflexive, symmetrical, nor transitive, and therefore cannot be characterized as one of equivalence or sameness, invalidating (2) and (3). It is also shown that other attempts to support (2) or (3), based on the Fields-Place principle or contextual control, fail to achieve their aim. It is argued that between the behavior of the speaker and the listener, there is a functional asymmetry that grounds the asymmetry of the referential relation, and typical SE and RFT experimental paradigms cannot capture it. Finally, some consequences for the study of the SE phenomenon and the study of symbolic behavior from the perspective of behavior analysis are discussed.