Humean phenomenology and Eastern “mindfulness” practice both lead to careful examination of what we actually experience. If it turns out not to be the sort of thing extravagantly metaphysical accounts of the self seem to suggest we experience, the correct inference to draw cannot be that the self is an illusion. The correct inference to draw is that extravagantly metaphysical accounts of the self are false. The careful inspection of consciousness for signs of a metaphysically extravagant self comes up empty. Our experience of those signs cannot be “illusory” if we don’t actually have them.
Anyone familiar with the extensive philosophical literature on the subject of subjectivity in the context of notions of free will and determinism will be tempted to respond via bibliography. I’ll instead focus on the question on its own terms, and as presented.
It is absurd to propose and in the same moment to limit as though objective a category of subjectivity.
The phrase “extravagantly metaphysical accounts of the self” already pre-judges and conceals the question. Any account of “the self” will appear “extravagant” from every conceivable alternative point of view. The position on the self – on Self as a universal or equally any self at all – is already a position on an infinitude and/or nothing, a category of subjectivity other than and opposed to objectivity.
The quantification implicit in “extravagant” as commonly used is senseless in this context: “Extravagant” means “wasteful, lavish,” but in its root simply means “wandering outside of.” So in that sense referring to the metaphysics of self as “extravagant” is tautological: The postulate of the self is the postulate of a “wandering outside of,” on the other side of “material existence.”
To be thought consistently it can’t be thought of as another material existent within material existence – e.g., as exclusively whatever cerebral-organic accommodations and furnishings where and within which thought might be thought to be thought, or as the material evidence of the experience of that thinking – and therefore quantifiable or comparable (relatively “lavish” or “wasteful”): To think of thinking in that way is merely to collapse the category back into that from which an absolutely fundamental distinction was to be thought.