One of the many amusing aspects of this play is the way in which Congreve presents us with characters who are supposed to be "wits" but are actually shown to not be wits at all. These characters are pitted against Mirabell and Millamant, the two characters who in my opinion show most "wit," in order to show the way in which manners have slipped. In particular, Congreve seems to use these false "wits" to present a rather crushing view of humans: Petulant and Witwoud for example are used to show the shallow nature of society and what we consider to be acceptable behaviour.
Mirabell and Milament, by contrast, although they are morally questionable in their activities, are shown to use their "wit" to achieve their aims and also distinguish between principles and what things are merely the passing vagaries of fashion. The various characters that these two come up against are shown to be weaker and ridiculous in comparison. Both Mirabell and Milament are able to use their intelligence and wit in order to remain both true to themselves and also to operate within a society where so much emphasis is placed on appearances and decorum. The fact that they are triumphant whereas characters like Lady Wishfort or not shows that they display the most wit.