What are the minimal conditions for intentionality that a sensory state should satisfy for it to constitute a representational state? That is, what are the limits of intentionality? This is the problem of demarcation. The goal of this paper is to assess a specific demarcation proposal for the minimal conditions of intentionality—the constancy mechanism proposal. Accordingly, it is a minimal condition for the intentionality of a given state that the sensory system should employ a constancy mechanism in the production of (...) this state. First of all, I introduce the problem of demarcation and show its relevance for the debate on the viability of naturalist theories of mental representation. After that, I present the explanatory role requirement for the positing of representational states by intentional explanations of behaviour and show how it constitutes a criterion for the assessment of demarcation proposals for the limits of intentionality. Finally, I assess the constancy mechanism proposal and show that its viability is seriously jeopardised by the minimal distance problem. (shrink)