To build a boundary is to create a place at which travel must cease. Metaphysics establishes boundaries of knowledge beyond which questions cannot pass--they are interrupted and rendered void. The creation of such boundaries is the translation of the unknown into the familiar. A home is created in the construction of boundaries that define inside from outside, and while the territory within becomes familiar, the territory outside is forgotten, or rather, slowly erased. By taking a horizon of knowledge and solidifying it in this way, metaphysics provides a framework within which questions can be replaced by Answers--answers of ultimate and final authority.
At the same time, the construction of a boundary of knowledge by metaphysics through a structuring of Answers gives rise to the possibility for the asking of Questions--questions posed directly to the present boundary of knowledge which are designed to pull it down from the outside. The construction of a boundary is never complete, and Questions seek out the inconsistencies inherent in Answers in order to re-mystify and challenge the authority of the Answers by liquifying their foundation. Once a boundary has been infiltrated, a horizon of knowledge becomes apparent.
A horizon is an ever-receding line stretched between the knowable (but not necessarily known) and the unknowable, which cannot be either encompassed or reached. Uncircumscribable by knowledge, it is itself that which ultimately circumscribes knowledge. A horizon, however, is not a boundary, as it does not limit or even delineate; rather, it is the vanishing point for knowledge that calls forth Questioning. It is the formulation of Questions that eventually leads to the creation of Answers and the darkening of the horizon into a boundary. The constancy of metaphysics lies in its Answers, while its movement and self-reflection stem from its Questions. As a discipline encompassing both its own consolidation and alienation, metaphysics is unique: it can never stand still, even though it continually creates platforms of knowledge upon which stillness is possible.
But as we have seen, physics and metaphysics are not so separate as some philosophers and physicists indicate, and in fact are in a sense symbiotic. Physics cannot exist without metaphysical postulates upon which it can rest its own theories, while metaphysics can in turn be directly influenced by physical experiments.
Ideally one could create physical experiments that tested metaphysical assumptions just as one creates physical experiments that test physical assumptions. Unfortunately, "experimental metaphysics" is not so easy, due to the fact that metaphysical theories are often formulated in such a way as to make direct experimentation impossible (and in fact this is one of the primary reasons for the avoidance or rejection of metaphysics by physicists, who rely heavily upon physical experiments). Usually this is a result of the sometimes excessive generality of metaphysical theories--they are loosely structured and can accommodate almost any new observations without detriment to their primary principles. The above analysis of Whitehead's metaphysics is a perfect example of how a tightly knit metaphysical scheme can adapt to new information without needing to be entirely re-formulated.
However, the physical testing of Bell's Inequality in Aspect's experiment shows that, despite the general malleability of metaphysics, something like experimental metaphysics is possible. The uniqueness of this particular situation stems from Bell's creation of the inequality; by restructuring metaphysical assumptions according to logical rules, he was able to formulate a set of propositions that could be tested in physical experiments. The peculiar difficulty of the work lies in the translation of metaphysical postulates into physical consequences that are testable in controlled conditions.
This type of work must almost necessarily fall to the physicists and those philosophers, logicians, and metaphysicians with scientific sensibilities, or ideally all of these in cooperation. The goal of metaphysics, however, is not merely to provide metaphysical principles that are able to be translated into physical situations, but to search for the proper first principles upon which all further explanation must rest as well. As a human discipline subject to human limitations (and human wonder), the claims made by metaphysics are necessarily biased in some form or another, but this does not detract from its importance as a background field upon which phenomena (be they physical, mental, or other) are seen to occur. If physics tells us what we can say about reality, then in one sense metaphysics tells us what we might be able to say about reality--but in another sense it tells us what we must say about reality at any given time. The former statement concerns the field of experimental metaphysics, while the latter concerns metaphysics in its broader, human context as a discipline that serves as the starting, or rather finishing point for explanation.
The search for truths in metaphysics should be supplemented by progress and advances that occur in physics, while physics should regard itself as being able to provide not final truths about reality, but truths that are dependent upon a more general metaphysical scheme. If metaphysics rejects physics as a valid partner in the search for truth, then its explanations can be valid to those who need final and ultimate answers, but the goal of metaphysics should not be to pose as any arbiter, but as the one that provides the best final and ultimate answers. If metaphysics limited itself to making the people that asked metaphysical questions feel better by giving them absolute answers, then there would be no need for any distinct metaphysical theory--any scheme would do that could provide this service. But metaphysics, although existing for this purpose, also exists as a discipline that seeks particular and unique explanations--namely, the best explanations, and the best explanations are likely to be those that correspond with what we know about reality through physics. But because metaphysics is a human discipline existing for human purposes, the best explanations will also likely be in accord with discoveries of other fields such as human psychology, biology, and ecology, to name just a few.
Of course the claims to truth made by metaphysics are questionable--this is in fact one of its greatest assets. We should not judge metaphysical schemes solely on the grounds of "correctness" alone (a problematic concept) but also by criterion of usefulness, application, and consequences. This is not to say that metaphysics must ultimately relinquish all claims concerning the ultimate nature of reality. On the contrary, by maintaining a certain level of self-criticism and humility, metaphysics can create for itself the possibility to transcend its own delusions. An answer to the question of whether or not there is one unique set of metaphysical principles that is "right" is itself a metaphysical question subject to all the limitations of metaphysical inquiry and understanding. Claims to knowledge are always conditional, and metaphysics, even as it creates its Answers simultaneously allows them to be destroyed. "Truth" then becomes both opaque and translucent, settled and unsettled.
If metaphysics does provide the decisive point at which explanation ceases, a
place where the question "Why?" can no longer be asked, then it can be dangerous.
The formulation of first principles in a metaphysical scheme is a delicate
matter with profound implications that ultimately affect not just ethics but even
the everyday modes in which we view and interact with the world.23 Because of
this it is important for metaphysics to nurture an intimate relation with physics
while not limiting itself by this relation. To formulate first principles that
are not only in accord with physics but also with ethics is one of metaphysics'
greatest tasks.
The question "Why?" can always be asked again, whether of physics, metaphysics,
or any other discipline, but the ultimate goal of the question is common: to
grasp truth. But "Truth" does not merely exist; it creates. Metaphysics is the
only discipline which can undertake the examination of "Truth" in reference to
both its existence and its self-creation, and as such it is indispensable.
On to the Footnotes.