  For Sorensen (2001), an individual’s acceptance of the truth of certain false claims, including those necessarily false claims of the form a is tall and a is not tall, reflect not the inadequacy of our semantic and logical analyses but the tendency for speakers to be wrong, confused, or ignorant about the truth conditions of given sentences or about their own beliefs, especially those involving vagueness, similarly to the way in which perceptions can mislead in the case of visual illusions.