If we trace western thinking on the ‘self’ back to Socrates and Plato, that tradition sought to find the ‘real’ nature of things through a process of reason such that thought, or the knowledge that it produced, might lead to an understanding of such a reality, and that what is observed is just a representation of some real or transcendent property that is only accessible through attainment of a ‘higher’ knowledge. There is thus a separation between what is observed and what ‘is’, or the appearance of ‘things’ and their true nature. This duality governed western thinking for many centuries, and was systematically framed by Descartes who saw the mind (or the subject) as something eternal and separate from the body. The ‘self’ in this view would be an approximation towards, and something separate from, a reality, or a ‘true’ nature. There was something essential and fixed about this true nature that could be objectified and observed through knowledge (or religious practice).
Although the work of Kierkegaard and (separately) Nietzsche were significant antecedents, it was the work of Husserl, perhaps, that brought about a radical departure within the western philosophical tradition, bringing the quest for ‘what is real’ to within a description of what is observed, and away from theological or scientific speculation and the pursuit of ‘knowledge’. From the perspective of phenomenology, perspectives on ‘self’ were placed squarely within the framework of subjectivity. Students that gathered around him included Heidegger, Levinas and Gadamer, a group of thinkers that are still very influential today in some psychological traditions.
While the importance of Husserl’s pioneering work is generally recognised, the ‘problem’ of the ‘self’ remained in so far it was now subsumed within an all-encompassing subjectivity (the transcendent subject), or perhaps transformed into the objective ontological entity of ‘being’ aka Heidegger. Ironically, the reification (and arguably objectification) of ‘being’ by Heidegger, was instrumental in the post-modern or post-structural dead-end of deconstruction that finally demolished the subject altogether. Sartre too was initially profoundly influenced by Husserl and phenomenology, and one of his first publications was a critique of the ‘transcendent subject’ that he encountered in Husserl’s work.
But it was Sartre more than anyone else (through his association with de Beauvoir, Merleau-Ponty and others), who founded a tradition of thought that can be described as western existentialism, and attempted to retain a sense of the subject (or ‘self’), while accepting that when we look away the ‘thing itself’ still exists. His statement that ‘existence precedes essence’ is perhaps meant as a clarification of the phenomenological tradition that allows for the paradoxical nature of the space within which we exist. Paradoxical in the sense that it recognises the subjective lens through which we experience the world, and hence gather a sense of ‘self’; while at the same time acknowledging that the lens as well as the ‘self’ so gathered are constantly being re-created by the objective (though conditional and contingent) context in which this sense exists, while in turn impacting upon that world. That space occupied by the ‘self’ therefore, is neither subject nor object in this case, neither one nor the other, but between the two, or both in dialectical relation; that which Sartre in his later work described as the ‘universal singular’. This paradox, I believe, is of fundamental importance to psychotherapy, as is the rescuing of the subject from both the determinism of Freud and the ravages of post-modern philosophy. For without an acceptance of a space within which a subject can engage with the world, there can be no concept of freedom (or choice) and no purpose in therapeutic engagement. Similarly, the idea that therapy can be about the revelation of what one already is, rather than traversing this dialectical process of becoming, and the alternative possibilities of who one might choose to be, seems both limiting and therapeutically pointless.