A strong trend in modern psychology is anti-essentialism. Drawing on post-structuralism and social constructionism, it posits that people do not have fixed and unitary selves, no essential or universal natures. Instead, multiples selves emerge and play out positions in various contexts and discourses; selves are constructed (Foucault, Harré, Gergen). The existential and humanistic psychologies of yesteryear are said to postulate such an unchanging self or person.
That’s all very well. Of course there is no fixed self.