For instance, a sentence like Tina walked does not entail the sentence Tina walked slowly . More generally, it underspecifies the manner of Tina's walk, as well as many other details about her and her walk. In practice, virtually all sentences are vague in this way, simply because we cannot expect one sentence to inform us about everything there is. However, it is often hard to judge whether sentences are ambiguous or just vague. In fact, the decision on this matter is rarely a purely pre-theoretical question and it often involves complex theoretical considerations, as we shall see later in this course.
Exercises Determine the direction of the entailment between the following pairs of sentences.
For the other direction show that there is no entailment by describing a situation that makes one sentence true and the other false. Tina is tall or thin. Tina is thin. Tina is neither tall nor thin. Tina is not thin.