Syntactic bootstrapping with clausal complements of adjectives

Like verbs, adjectives pose a challenge to the young word learner in that some - like red, round, rough, or rectangular - map onto properties that are detectable through the senses, while others - like ready, reasonable, or required - express abstract properties that have no reliable, physical correlate. Even for those adjectives whose properties are observable, how does a child know that one particular property is being highlighted above all others? The physical environment alone will not suffice. Just as with verbs, the child learning adjectives is faced with an inherent indeterminacy of meaning, which can only be resolved through the incorporation of cues originating from multiple sources.