The present paper offers a contrastive examination of French items that require some knowledge of the speaker and items that require some ignorance. We relate this difference in a systematic way to the well?known problem of ?identifiability'in epistemic logic. In addition to providing a more precise analysis, this identification-based investigation leads us to two findings. First, non-identification (?ignorance?) is actually a particular manifestation of the more general phenomenon of free-choiceness, which has received much attention lately. Studying non-identification helps us to gain a better understanding of the varieties of free-choiceness. Second, identification (?knowledge?) has to be distinguished from specificity, understood as wide scope of an existential quantifier, and to be evaluated in the perspective of a full-fledged epistemic theory including epistemic agents and descriptions. This questions the scope-based analyses of determiners like un certain in French and a certain in English and gives a central place to the phenomenon of relativity of description, whose importance is independently motivated in recent work on reference.