In this paper, we describe an approach by which one agent may infer the categorical preference structure of another agent in relation to a set of alternative proposals made in negotiation. The categorical preferences are inferred over a sequence of proposals, as preferences are disclosed one at a time. We seek to avoid strong ontological commitment between the agents, making only minimal assumptions about shared representations of the set of alternatives. We adopt a multidimensional representation that avoids the common, but rarely plausible, assumption of issue independence. An illustration of the approach is included and possible applications are discussed.