 Finally, linguistic facts play an important role in the debate about the existence and nature of numbers. Frege’s (1884) theory of numbers as abstract objects was motivated by sentences such as the number of planets is eight, an apparent identity statement containing two apparent number-referring terms. More recent linguistically oriented research has put into question whether eight in that sentence really refers to a number rather than keeping its “adjectival” meaning (as a quantifier or plural property) and moreover whether the number of planets in that sentence is really a number-referring term rather than acting as a “concealed question”, standing for the question about how many planets there are (Romero 2005; Hofweber 2016).