How does Jonson use comedy as an instrument of moral vision?

In Volpone, Johnson uses comedy in the form of dramatic irony. At any given time during the course of the play's action, no characters on stage know as much as the audience; they are all thus ignorant, though some are more ignorant than others. Jonson's extensive use of dramatic irony ensures that only the audience is fully aware of each character's situation. Not even Mosca, the master puppeteer, knows that Corvino and Celia will come to the door earlier than expected and that, as a result, Bonario will leap out and discover Volpone's scam. Jonson plays with the knowing position of the audience, inviting us to consider their moral failings from an unsurprised position. Thus he equates ignorance with moral chicanery and knowledge with moral instruction.

This knowledge-ignorance dialectic develops the conflict of both the main plot and the subplot. Sir Politic, who epitomizes ignorance, and Peregrine, who epitomizes knowledge, clash in predictable ways. On the subject of the mountebanks, for example, Peregrine has his reservations but Sir Politic declares that "They are the only knowing men of Europe!" (2.2.9). And, however ironically, Peregrine is supposedly being instructed by Sir Politic in the ways of a gentleman traveler. Sir Politic and Peregrine's interaction might best be summarized by the maxim which says, "Wise men learn more from fools than fools from the wise."