Sentimentality vs. Practicality
Refusing two marriage proposals, Vivie Warren demonstrates herself to be asexual and practical. Frank, too, is quick to make judgments based not on his emotions, but on what is practical for his finances and the future. In contrast, Mr. Praed and Mrs. Warren are quite sentimental, and Vivie is disgusted and impatient with this personality trait. Although Mrs. Warren is shrewd and manipulative in the eyes of most of the other characters, when faced with Vivie's practicality and coldness, she is weakened.
Male privilege and the objectification of women
Shaw took issue with the objectification of women, which he saw as permeating all levels of Victorian society. Male privilege is often unrecognized by the characters who benefit from it, but Vivie and Mrs. Warren speak of it as a given. Mrs. Warren has chosen one of the only professions available to women who wanted to remain independent from a man at that time. Vivie respects this in her mother, but demands her own independence as well - she goes about achieving it by focusing on her education and career.
Convention and the "New Woman"
Many of the characters invoke the idea of being "conventional" or "unconventional" as a personality trait either in themselves or other characters. Vivie clearly rejects conventions in relation to what it means to be a woman and what is expected of her gender; she refuses to marry or take care of her mother, Mrs. Warren. In these ways, she exemplifies the "New Woman," a feminist ideal described by Winnifred Harper Cooley in her 1904 publication The New Womanhood. The idea had been around for decades, and Shaw was a proponent of it: the "New Woman" was independent, educated, and practical. Mrs. Warren, too, is unconventional in that she became a prostitute and continues to manage brothels.
Love as a commodity
Shaw challenges the audience member's conception of what constitutes commerce and, consequently, work. Prostitution is often looked down upon as shameful because it is a commodification of sex, but the characters point out in various ways that marriage, too, is a commodification of women, albeit a more conventional one. As Mrs. Warren points out in her Act II conversation with Vivie, prostitution is work; like marriage, it is not enjoyable for most women but it is a way to survive.
The relationship between mother and daughter
Vivie accepts her mother's decision to become a prostitute, but rejects her as a mother upon discovering that Mrs. Warren continues to own and operate brothels. Mrs. Warren has never been much of a mother to Vivie, although she has financially supported her and provided her with an impressive education. The way that Vivie speaks to Mrs. Warren and Mrs. Warren's fear of her daughter turns the traditional power dynamic of the mother-daughter relationship on its head.
Secrets
Throughout the play, the main secrets are Mrs. Warren's profession and the identity of Vivie's father. The way the characters choose to keep or reveal their secrets demonstrates their personality traits. For example, Mrs. Warren's profession is a secret Mr. Praed keeps from Vivie in Act I, but by Act IV Vivie knows more about the details of her mother's life than Mr. Praed, and it is she who painstakingly reveals those details to him and Frank. In sharing the secret of her profession with her daughter in Act II, Mrs. Warren leaves out the fact that she continues to work as a prostitute and run brothels. She knows that Vivie will relate to her practicality in choosing her profession, as well as her desire for independence as a woman. And in fact, it is this bit of information that turns her daughter against her.
The idea of morality
Mrs. Warren and Vivie continually bring up the idea of "doing the right thing," and their understanding of what that means differs. Vivie can understand that Mrs. Warren's turning to prostitution made sense as a practical life decision, but cannot justify her mother's continued participation in the sex work industry. Crofts, too, has a strong opinion about morality. His is a cynical approach: he claims Vivie is naive for not recognizing that everyone of any social standing in life behaves quite immorally.
