Final answer:
Dramatic irony in literature, such as in Shakespearean plays, occurs when the audience holds knowledge that some characters do not, which heightens the emotional impact and tragedy of the plot.
Step-by-step explanation:
The reason for dramatic irony in a situation such as the one described with Petruchio and Katherine in 'The Taming of the Shrew' is rooted in the audience's knowledge of events or character's thoughts that some characters in the play are unaware of.
Taking Shakespeare's 'Romeo and Juliet' as an example, the audience is acutely aware that Juliet is not truly dead but merely under the effect of a sleeping potion. This knowledge builds dramatic irony, as Romeo does not have this information and acts in devastating ignorance by taking his own life. Similarly, in 'Macbeth', Lady Macbeth's sleepwalking scene creates dramatic irony through the audience's awareness of her guilt, which other characters do not see. Such elements enhance the emotional engagement of the audience, create tension, and deepen the tragedy of the unfolding events.