Metaphysics is a filthy word. Not inherently, I don't mean to suggest that metaphysics is itself filth. Rather, it has been sufficiently degraded by its proximity to filth through the idle leisure of the theory class. This leisure was largely a prosocial activity when metaphysics was the domain of academic and/or priestly brahmin, operating within the confines of a system of social pressure demanding mathematical and philosophical rigor, but over the course of the nineteenth and twentieth centuries metaphysics was often exported from those temples and universities into democratic contexts that it had no non-coercive use within. The popularization of dissociative metaphysics and, in tandem, the rise of naive rationalism have produced a general population with extreme blindspots concerning the architecture of any given cognitive process.
Since time immemorial, there have been many attempts to use metaphysical justification as a method of confounding the senses and passions into the anesthesia of solipsism. Perhaps the strongest contemporary tool in the arsenal of the solipsist is the ability to invoke quantum physics to give a sense of pseudoscientific legitimacy the claim of psychic causality. The fallacy of psychic causality can be specified as the belief that mental states can affect the world when the content of said mental states cannot be channeled through physical action on the substrate of the world. While I believe that, for instance, Schoppenhauer's interpretation of Gautama is philosophically sound, the same cannot be said for Deepak Chopra's superficially similar claim that the world is "made of consciousness." He and, for instance, Charles Eisenstein, should be categorized in the same unit as Rhonda Byrne, the author of The Secret. Metaphysics has become popular shorthand for the art of marketing lotus eating as something intellectually prestigious while conflating dissociation with philosophy. Another basic strand of New Age "metaphysical" thinking is the conflation of metaphysics with the "meaning" of reality, a belief which at least implicitly implies that there is a perspective external to and surveiling the self, interpreting the actions taken by the self. While indeed this may be a valid interpretation of the world and there certainly is a valid metaphysics for operating within this kind ontology, it artificially prunes the possible ontologies that an individual could consider themselves to exist within to those that are tacitly theistic.
These confusions have unfortunately shifted the metaphysics of a significant amount of the population such that they believe that they do not in fact have a metaphysical position. This has rendered the deepest conscious level of the psychological stack invisible, forcing one to model the mind's thought process as beginning with epistemology, rather than beginning with metaphysics. Though the Popperian empiricist perspective taken by the majority of the sane world is logically sound internally to itself, it is fails to describe how such a unit must be loaded into a larger apparatus as a component part. In order to take the perspective that probabilistic empiricism is correct, one must have already taken the perspective that the abstract values of reason, statistics, and observation are themselves valid. Aristotle did not reject Plato's rationalism, he simply placed empiricism as a valid partner alongside it by choosing to trust his senses instead of rejecting them—a position we must understood as informed by a likely period of considering the position of rejecting the senses, supposedly commonplace among the Athenians at the time. The act of marking a type of information significant is a metaphysical value judgement about what reality is, which is to say which parts of phenomenology can be understood to be consequential. The judgement to begin an empiricist endeavor is first dependent on a metaphysics, even if the empiricist endeavor then feeds back on the metaphysics that created it in the first place, updating the conception of valid information from phenomenological impressions.
Though I have not become a proper scholar of his work, I am fairly sure that I am simply retelling the work of David Hume in a personal context. I am not interested in figuring out which of these ideas are mind and which are his, if he was in my place I would hope he would do the same thing and avoid the academic citation war and instead focus on the ways that metaphysics is not entitled navel gazing. Hume's position, reliably, is that of a man who has not been broken by coercive circumstances, and who has not been coddled and thus understands himself to be a finite being with finite capacities for knowledge. Instead of attempting to figure out how much I am channeling his ghost, I want to discuss the distinction between the positions of David Hume and Martin Heidegger, the man of principled custom and the man of dasein.
Hume knew that it was correct to lean on our accumulated knowledge about the world even if we knew in our hearts that no matter how much analytical knowledge we produced we could not rely on it as evidence that the world was somehow predictable. The fundamental physical constants could lose their relationship to one another, and in doing so the whole world would unravel. (I do not suggest that the individual values of each constant varying would cause a problem, as if motion is relative the forces of each constant varying as a whole, but preserving the same relative strengths to one another would, I think, likely do nothing noticeable to the universe.) Still, we had to retain faith in our ability to discern cause and effect and treat that knowledge as dependable, if potentially badly motivated viziers. Custom is a good guide, even if at any moment our entire frame of reference might be incorrect, and we may find ourselves awake and alone in a sea of unpredictability. The key thing that Hume knows, is that custom must be tempered with humility. We must remember that the Socratic maxim that, in fact, we do not know anything is still true. No matter how much of the map we fill in, it still can never be the territory. This is not something that I think Martin Heidegger ever knew.
If the subjects of philosophy are ourselves as Heidegger believed, then it is potentially correct to embrace solipsism as we cannot prove that there is something other than ourselves that we are studying. I think this is the central message of Being and Time, both in the medium/style/metadata of the book's format and the text itself. The book's obtuse structure causes the reader to experience cognitive dissonance and come to think that there is more to the philosophy contained within than there actually is. It would be, I think, far more correct to simply embrace the anarchic egoism of Stirner than to try and parse through Heidegger; the end result is the same, and Stirner is far more honest about what he believes. For, to Stirner, the best thing to be was an honest solipsist and to embrace the drives of the individual as they are the only things that can be verified. Heidegger cannot bring himself to admit that he is only a solipsist embracing meta-nationalism as he lacks the introspection to see that he is pacing the walls of a prison of himself, hoping that something will change.
If we are attempting to be authentically who we are in the present moment then we imprison ourselves in the state of mind that we have already been. We may narratize it as a style of being, a certain pattern of being-in-the-world, but it is still an inability to act in time, to coordinate with our future selves and even with the potential of being informed by the actions of our past selves. Mill wrote that it was wrong to sell oneself into slavery, and as such it is also incorrect for one to be attached to a present identity, for a future identity may take the place of the present and one may be better for it, how could you know except from the point in time where the choice is relevant?
Heidegger makes the same mistake as popular Popperianism, but in reverse. He focuses on the sense of being, deriding the potential of mapmaking as mere techne, mere "enframing" of the world into something that lacks the possibility of the naive will. Popular Popperianism sacrificed the experience of the territory for the power of the map. Heidegger sacrificed the knowledge of the map for the power of the territory alone. It is a good way to coordinate with clones of yourself, to mass great forces of self-similar agents who think that they have access to the thing-in-itself to the degree that they can be themselves, for they are in contact with the only reality that they can know to be there under their metaphysics. But this is a poor epistemology with a rich metaphysics, leaving men like Otto Hahn crying out that there is something that has been overlooked to disastrous effect by both the Popular Popperians and the Daseinbots.
As an aside, I believe that a similar conflict to the one that I am trying to address with Heidegger and Hume appeared much more directly between Noam Chomsky and B.F. Skinner in the postwar period, but the details of that conflict are likely best left for a different discussion, but to begin I would recommend looking at Chomsky's Language and Mind, and Skinner's Verbal Behavior.
For the Edinburgh Group, and for F. L, a man who gave me the gift of some wrong answers to all the right questions.