In philosophy, vagueness is an important problem in semantics, metaphysics and philosophical logic. Definitions of this problem vary. A predicate is vague if it has borderline cases. The predicate "is tall" is vague because there seems to be no particular height at which someone becomes tall. Alternately, a predicate is sometimes said to be vague if there are borderline cases of its application, such that in these cases competent speakers of the language may faultlessly disagree over whether the predicate applies. The disagreement over whether a hotdog is a sandwich suggests that “sandwich” is vague.