Marketing Beyond Broadening: Boundarying and the Cumulative Development of Marketing Theory

Marketing's broadening has enabled the discipline to engage diverse phenomena, but it has also created a theoretical problem: empirical relevance does not necessarily constitute a marketing contribution. This commentary identifies this theoretical dilemma as the Broadening Paradox and introduces Boundarying as a way of addressing it. Rather than defining fixed disciplinary limits, Boundarying asks whether emerging concepts advance marketing through distinctive explanatory mechanisms. We develop three diagnostic principles these are value proposition, reciprocal stakeholder relationships, and stakeholder responsiveness to assess whether concepts explain participation, value formation through interaction, and adaptation through stakeholder feedback. Illustrations from artificial intelligence, government regulation, and corporate sustainability show how the same phenomenon can generate different theoretical contributions depending on its underlying explanatory logic. Boundarying therefore complements rather than constrains broadening by shifting attention from where marketing is applied to what marketing explains. The commentary offers a basis for developing more cumulative and theoretically distinctive marketing knowledge.