What is the dramatic effect of Act 3, Scene 2 in "Much Ado About Nothing"?
It's a key scene, I think, because it's the point at which the play seems to violently shift from comedy toward tragedy. It even opens with the sense that everything's already been wrapped up:
I do but stay till your marriage be consummate, and then go I toward Aragon.
I'll bring you thither, my lord, if you'll vouchsafe me.
The men are making to leave Messina. Then there's a whole barrel of jokes about Benedick, and about his new appearance. Like everything else in the play, it's based on an idea of seeming versus reality. Benedick, of course, isn't really a lover (though he thinks he is, based on his gulling - another case of seeming versus reality!) but he appears to be one. And Claudio and Don Pedro are happy to point out that Benedick isn't dressed like Benedick on this occasion:
If he be not in love with some woman, there is no
believing old signs. A' brushes his hat o' mornings. What should that bode?
It's all very comic and very good-natured. And then, in the space of one scene, suddenly Don John appears with another case of seeming versus reality. They are to see Hero seduced at her window, according to Don John:
If you dare not trust that you see, confess not that you know.
And the scene ends with an acknowledgement that it almost seems like the second part of the play - a tragedy coupled onto the comedy:
So will you say when you have seen the sequel.
Comedy into tragedy - no scene change. It's a pivotal scene.