Peachum and Mrs. Peachum are in their shop. Polly stands in the doorway carrying a traveling bag. She sings a song explaining her decision to marry Macheath. In the song, she describes how she grew up learning to protect herself from love. Even when the fellow was nice, had money and clean shirts, and treated her with respect, she learned to tell him no. But then she sings about how she met a fellow who was not nice, did not have money, wore dirty shirts, and showed no respect, but she could not tell him no. She refers to how the moon shined so brightly to her one evening that she decided to give love a chance.
Peachum and Mrs. Peachum are furious with her. They rail against her for leaving them. Peachum especially emphasizes how Polly getting married will impoverish him. Then five of Peachum’s beggars enter. One of them complains about his fake stump, which he says is totally inadequate, and he is not taking in enough money. Peachum replies that it is not his fault but gives the beggar another stump to try on. Meanwhile, Peachum examines the other beggars and finds them wanting. They are not sufficiently pathetic to his taste. One of them has even gained weight, so Peachum fires him. Peachum says that artists need to tug at people’s heartstrings. The beggars exit.
The family returns to their argument about Macheath. Polly defends Macheath, saying that he earns an excellent income. Peachum makes the argument that when a girl is married, the first thing she does is get divorced. Mrs. Peachum agrees that many people are seeking divorces. Polly protests that she is in love, and her mother says that Macheath has a bunch of different women and that when he is hanged, many of these women will enter the scene. The word hanged sparks an idea in Peachum. He sends Polly out and then tells Mrs. Peachum that he will report Macheath to the sheriff, collect the forty pounds’ reward, and get Macheath hanged. Mrs. Peachum says she even knows where to find him: at Wapping, with the whores whose company he cannot live without. Polly has been listening at the door and re-enters to tell her mother that Macheath would rather go to jail than to visit the whores. She adds that even if Macheath went to jail, Brown would help him out because they are best friends. She tells her father that there is no record against Macheath at Scotland Yard. Peachum is confident that his scheme will work, though. He remarks that the world is evil and that everyone has to fight to keep what is his or hers all the time.
Then all three step forward to sing “First Threepenny Finale on the Uncertainty of Human Circumstances.” The song begins with Polly protesting her love, and Peachum responds that everyone has a right to happiness, but just because something fulfills Polly’s happiness, it does not mean Polly should have it. He adds that if everyone was good in the world and did not commit crimes, heaven would be a reality. However, the world is no heaven, and Peachum says that there is not enough of heaven to go around because morals are lacking. The world’s condition will not permit goodness. Mrs. Peachum and Polly take up his refrain about how miserable the world is. He describes how everyone would like a paradise, but when there are limited resources, even one’s family will steal to survive. The song ends with all three directly addressing to the audience, reprimanding them for ignoring the stupidity and baseness of the world.
This scene demonstrates false or vile reasoning may be used to make correct arguments. Macheath has a powerful ally in Brown, but Peachum thinks he can overcome that. The audience is in the ironic position of rooting for a murderer, thief, and adulterer to remain free. The arbitrariness of values is further developed through Peachum’s and Mrs. Peachum’s ironic attempts to convince their daughter to divorce Macheath. The irony of the scene lies in the fact that they are right that Macheath is not a good match for their daughter. He is dangerous, and he is also an incurable womanizer. The reasons that they argue their positions, however, are not based on their daughter’s welfare. Instead, they argue for Polly to stay with them because if she is not at the shop to help attract more clients, her absence will ruin the business. The Peachums disapprove of Polly’s marriage because they worry about their finances, not the safety of their daughter.
The scene further develops the contrast between Polly and Peachum. Polly is motivated by love, and Peachum is only interested in the financial gain of his business. Over the course of the scene, Peachum’s view comes across more strongly when he continues to speak over Polly. In her telling, love is an unstoppable force that is not about money or decency but about a true feeling. This declaration is incomprehensible to Peachum, of course, because anything that does not make one richer is folly to him. In his mind, Macheath is a competitor trying to take away one of his key assets, his daughter. Peachum’s argument forces his daughter to use economic terms to make her case. She claims that Macheath makes good money. Peachum pushes further and further, until by the end of the scene his view dominates. Polly and Mrs. Peachum sing along while he makes the case that everyone should only look out for themselves, and in this instance, Peachum looks out for the profit of his company.