Do thriving democracies need to be monolingual and monocultural?

Lecture given during the "Considering Monoculture" conference, deBuren, Brussels. February 28, 2020.

In order to form a thriving political community, do we need to be a people, a nation, defined by a common culture and therefore also a common language? If so, how can this be reconciled for countries, and especially cities, with increasingly diverse and fluid populations? If not, what else is needed for a workable democracy? These questions are addressed with special reference to Brussels, Belgium and the European Union.