Deception is the foundational basis of A Doll's House. Nora practices deception to save Torvald's life through money gained from a loan to which she deceptively signs her father's name. She continues her daily deceptions inherent in paying back the money. she deceives on large and small things, such as the macaroon cookies. Dr. Rank practices deception in maintaining his friendship with Torvald while secretly in love with Nora and with Nora by acting the friend when his feelings are deeper. Torvald practices deception in his role with Nora, acting like a loving husband but in reality putting values of honor and pride ahead of her.
Each instance of deception is motivated by different feelings or purposes. Nora's initial deception was motivated by her husband's illness with the purpose being to save his life. Her continued deceptions are motivated by the need to repay the loan and the taste of independence and freedom that the whole incident opened up to her. Dr. Rank's deception is motivated by the bounds of honor--it is dishonorable to love your friend's wife--and by his deep love for Nora. He has a double purpose: to be loyal to Torvald and to be near Nora. Torvald's deception is motivated by a character flaw that values honor and pride above human and family relationships. His purpose is to have a lovely wife and a lovely life with all the appearances of propriety, moderation, and pride that he values.