Allport’s contact account lacked mechanisms and generalization logic, hence only rated as a hypothesis

Evidence

Moreover, Allport’s formulation specified neither the processes involved in intergroup contact’s effects nor how these effects generalize to other situations, the entire outgroup, and other outgroups not involved in the contact (Pettigrew, 1998). Indeed, these omissions explain why he called it a “hypothesis” and not a “theory.” — John F. Dovidio, Peter Glick, Laurie A. Rudman, On the Nature of Prejudice, 1707

Categorization

• DEFINE: Clarifies the distinction between hypothesis and theory as Allport himself applied it, and why that labeling revealed genuine explanatory gaps.