Abstract
The study of English once and twice yields evidence that each of them is actually a complex phrase containing two visible morphemes and one silent one. Neither is a simple lexical item. The -ce morpheme is akin to a postposition, despite English being primarily prepositional. The silent element associated with once and twice is a silent counterpart of time, represented as TIME. This instance of TIME is singular, even in the case of twice. There appears to be a link between TIME and the syntax of classifiers.
The presence of silent TIME with once and twice indirectly provides evidence for the presence in the human language faculty of other antecedentless silent nominal elements such as NUMBER. Silent elements of this sort are not visible (even via an antecedent) in the primary data available to the learner. Their properties, for example, their singularity or plurality and their licensing conditions, therefore provide us with a privileged window onto the invariant core of the language faculty itself.
The presence of silent elements such as TIME and NUMBER can, in part, be traced back to a principle of decompositionality, to the effect that the human language faculty imposes a maximum of one interpretable syntactic feature per lexical item.