Idealism, particularly in its subjective form, asserts that reality is fundamentally mental or spiritual in nature, and that the self is a unified, indivisible entity.

Psychological continuity theory holds that personal identity is primarily determined by the continuity of one's memories and experiences over time.

Qualia are the subjective, qualitative aspects of conscious experience, such as the taste of coffee or the feeling of pain.

Non-dualism, particularly in its Advaita Vedanta form, asserts that the self and the universe are fundamentally one and indivisible.

Psychoanalysis, particularly Freudian psychoanalysis, posits that the self is divided into conscious and unconscious components, with the unconscious mind influencing thoughts, feelings, and behaviors.

Post-structuralism, particularly the work of Michel Foucault, argues that the self is constructed and shaped through discourse and language.

Phenomenology, particularly the work of Edmund Husserl, emphasizes the study of conscious experience, including the flow of thoughts and sensations known as the stream of consciousness.

Skepticism, particularly Pyrrhonian skepticism, questions the possibility of attaining certain knowledge, including knowledge about the nature of the self.

The self-concept is the subjective, mental representation of oneself, including one's beliefs, attitudes, and values.

Social constructivism, particularly in the work of George Herbert Mead, posits that the self is formed through social interactions and that it is shaped by cultural norms and values.

Existentialism, particularly the work of Jean-Paul Sartre, emphasizes the importance of authenticity and the need for individuals to create their own meaning and purpose in life.

Materialism, particularly in its physicalist form, asserts that the self is composed of physical matter and that consciousness is a product of brain activity.

The looking-glass self theory, proposed by Charles Horton Cooley, posits that our self-concept is influenced by how we believe others perceive us.

Libertarianism, particularly in its metaphysical form, asserts that the self has free will and that it is not causally determined by prior events.

The extended self theory, proposed by philosophers such as Andy Clark and David Chalmers, posits that the self extends beyond the physical body to include one's social and cultural environment.