The paper answers the title question via its methodological commitment to a Husserlian description of the acts of consciousness which we cannot but perform when we engage in linguistic communication. Familiarizing the reader with the central terms of the German Vorstellung and Vorstellbarkeit (imaginability) and their prominence in phenomenological inquiry in the Introduction, the paper addresses major uses of Vorstellung from Kant to Husserl, before identifying imaginability as the hidden core of natural language, captured in a re-definition of language and (...) linguistic meaning. The observation that imaginability affects all linguistic aspects from phonology to pragmatics is followed by the claim that it is primarily a communally shared form of. The last Section offers a speculative, radically gradualist thesis of language evolution in opposition to dominant catastrophe theories, with the conclusion summarising the answer to the title question in terms imaginable, schematized resemblance relations. (shrink)