The political theorizing of language is unavoidably reliant on at least certain basic assumptions concerning the nature of language and linguistic agency. In multilingual and multicultural societies such as Canada, the task of identifying, articulating, and ultimately evaluating such assumptions is more complex, given their more heterogeneous linguistic landscape, and the (sometimes conflicting) clusters of beliefs, attitudes, anxieties, hopes, and expectations attached by speakers to particular languages as well as to the broader repertoire. The chapter focuses its attention on the debate over multiculturalism/interculturalism in the Canadian context. It explores and defends the argument that this debate can be seen in fact as a debate between two distinct conceptions of language and linguistic agency, namely the designative (“Lockean”, i.e., language as detached from a partial and intersubjective human experience) and the constitutive (“Herderian”, i.e., language as inextricably linked to a contextualized social epistemology), respectively. The distinctive logic and reasoning of both models, the chapter argues, can only be defended by embracing a non-holistic “in-betweenness” experience (and conception) of language as an underlying constitutive commonality.