In all of Molière's plays there is always at least one character who represents the voice of moderation and rationality, qualities which were greatly admired by the age during which Molière lived. At the beginning of Act IV, it is obvious that Cléante functions as the expression of the reasonable view. In talking with Tartuffe, Cléante displays unassailable logic. He points out that Tartuffe is not acting as a truly religious person should and also demonstrates that Tartuffe's logic is faulty. For example, when Tartuffe tries to justify his taking Orgon's money and property so as to keep it from falling into wicked hands, the irony is double here because there are no more wicked hands than his for it to fall into; then, when Cléante reasons that the burden of handling such money should belong to Damis, that the son should be allowed to bear the burden, and that true religion does not demand that a person be disinherited, Tartuffe is unable to withstand this onslaught of logical consistency. Thus, as Cléante begins to trap Tartuffe by sound reasoning, Tartuffe suddenly realizes his danger and leaves with the hypocritical statement that he has to attend to some pious duties.
Throughout the scene, Cléante does not realize that he is dealing with an unmitigated scoundrel and part of the comedy of this scene depends upon how the scoundrel cleverly escapes the rationalist's traps.
The entire situation becomes more desperate as Orgon insists upon the marriage taking place that very night. This forces everyone concerned to create some plan of action so as to undeceive Orgon.
