It seems, according to DeBeauvoir, that a new feminist movement began because of inequality of women and the title of "other" given to women. It was said that women were negative and men were position and they were in a more superior position, they are normal while the woman is deviant. To the man the woman represent "sex-absolute sex, no less" (304). In other words women are just a different sex, they are not real people, they just represent a change in sex, something other than male and nothing more. Also statements like " a man is in the right in being a man; it is the woman who is in the wrong" would also provoke a woman to start a new feminist movements because these kinds of statements dehumanize women and make them feel worthless (304).
I think that in general women were fighting to be independent and seen as true beings and not just defined as relative to man. Women wanted to be equal. Many may have said that if the woman is liberated then the relationship between woman and man will be corrupted and or destroyed, but DeBeauvoir tries to make people see that if women are treated equally "the human couple will find its true form"(305). She basically says that things will be better if women are seen as equals, the truth will prevail. Women also want the power to define themselves and not be defined by man.
To support her cause, or the reasons that pushed her to write this piece and participate in a feminist movement, were claims made by Aristotle like "the female is a female by virtue of a certain lack of qualities, we should regard the female nature as afflicted with a natural defectiveness"(304). Also statements made by St. Thomas that the woman is ""an imperfect man" [and] an "incidental" being"(304), and others like Michelet who believes that man is independent of woman whereas women are dependent on men and cannot be without him. She uses these statements made by Aristotle, Michelet, and St.