A common theme in 20th century philosophy, and continuing to this day, is skepticism concerning the possibility of metaphysical inquiry. Logical positivism is probably the biggest historical influence here, but is not one of the primary surviving general criticisms of metaphysics. Most criticisms of metaphysics come from outside philosophy, and I’m not going to address those specifically, because most of them fall under the umbrellas of the various philosophical criticisms of metaphysics.
But I think metaphysical inquiry is not only possible, but necessary. It is inescapable. Here I present responses to what I think are the main objections to traditional metaphysics; relativism and contextualism, naturalized epistemology and scientism, Kantian idealism, and semantic objections.
NOTE: My conception of metaphysics is as an inescapable/universal discipline of a not-wholly-empirical character concerned with investigating the nature of ultimate reality.
1. Relativism
Strong relativism in all its forms denies the indivisibility of truth; for example, in historical relativism, what may be true for one historical epoch might not be true for another. Or as is the case in cultural relativism, different cultures supposedly have radically different and incommensurable conceptions of rationality. The problem here is that this is itself a metaphysical claim; it is an indivisible claim (“all truths are not indivisible”) that does not fall in the domain of any special science! Any person who espouses this doctrine has to concede that they are engaging in metaphysical reasoning as traditionally conceived. Furthermore, while I personally think that truth [i]is[/i] indivisible (I am not a relativist), this doctrine is not essential to metaphysical inquiry per se, as the question of truth’s divisibility is itself open to metaphysical investigation.
Those who support the program of naturalized epistemology, often called Quinean naturalists (after one of the movement’s key figures – W.V. Quine), are skeptical of metaphysics as conventionally conceived from a scientistic perspective. The idea is that any sort of knowledge we could possibly obtain must be compatible with our status as a kind of animal which as come to be through the wholly natural process of biological evolution. Thus, epistemology is properly conceived as a part of psychology.
Under this view, any knowledge of “fundamental” reality we’d have would have to be the sort accessible to such creatures with such biological capacities. Now, in a vacuum this would be trivially true, but given the premise presented in the last paragraph (that any sort of knowledge we have must be compatible with our status as a sort of creature with knowledge-gaining traits selected through evolution), this means any sort of putative “metaphysics” must be of the sort that is knowable by the same processes (namely, natural science). Such a “metaphysics” would more accurately be described as a part of natural science.
The problem here is that this line of thinking aims to undermine itself in the same manner as relativism. First, Quinean naturalists are not clear about why our status as a certain sort of naturally-selected animal closes off the possibility of distinctly metaphysical knowledge, but not that of scientific knowledge. The core of the Quinean argument is why we would have evolved capacities to gain metaphysical knowledge, if such investigative capacities are not directly advantageous to survival. But how does science fare any better under this view? If we accept Quine’s view of the implications of evolution for knowledge (which also could in itself be challenged – one could construct scientific arguments as to why metaphysics-tracking processes could evolve), then it is equally difficult to see why we would have evolved the capacities to investigate such matters as the formation of black holes.
Second, natural science cannot presently explain how or why creatures such as us became capable of scientific knowledge. But this is not the same as saying that it is not possible for natural science to explain it. So the fact that the same science cannot presently explain how or why creatures like us are capable of metaphysical knowledge is no reason to believe that science cannot in principle explain the capacity for such knowledge, or that such knowledge is impossible. Furthermore, if we thought that the fact that natural science is presently unable to explain a certain sort of knowledge means that knowledge is impossible, we’d have reason to believe that scientific knowledge is itself impossible, and in turn the Quinean can no longer appeal to the very scientific theories upon which their idea relies.
Quinean naturalists and other “scientismists” display what philosopher E.J. Lowe describes as a “curious lack of self-awareness” when they cast humanity in a severely scientistic and anti-philosophical light, not realizing that this in itself constitutes a sort of thinking which is supposedly invalid under their worldview.
3. Kantian idealism
Another criticism of metaphysics as conventionally conceived came from Immanuel Kant. He argued that the proper aim of metaphysical inquiry was not to investigate the structure of some mind-independent reality, but to investigate the structure of our thoughts about reality. The reason for this move was that Kant thought this change in our understanding of metaphysical discourse was necessary to preserve certain metaphysical truths he thought we certain.
Like the other challenges to metaphysics we’ve explored so far, Kant’s fails because it is, again, a conventional metaphysical theory in itself. Even if Kant is right about us investigating the structure of our thoughts, these thoughts constitute enough of a mind-independent reality, in a minimalistic sense, to vindicate traditional metaphysics. If we understand a “mind-independent reality” to be one such that the features of said reality are not dependent on our thinking of them, our thoughts are a sort of mind-independent reality. Of course, our thoughts cannot exist (in whatever putative sense they’re said to “exist”) without our thinking them, but they do not require we think of them. After all, if we had to think of our thoughts for them to exist, we’d have an infinite regress of meta-thoughts about thoughts. Kant’s view has simply collapsed to conventional idealism! The suggestion that thoughts are the sorts of things that constitute reality is a traditional metaphysical theory; a possible response to standard metaphysical questions.
4. Semantic objections
Semantic objections to the possibility of metaphysics became the norm in the first half of the 20th century. Both the logical positivists and the ordinary language disciples of later Wittgenstein thought metaphysical problems were actually pseudo-problems, and that metaphysical language was literally nonsense. Today still, some scientismists and contextualists decry the possibility of non-empirical knowledge about reality.
Such challenges are odd upon closer examination. Metaphysics seeks to investigate what is necessary and what is possible, rather than what actually obtains. So questioning the possibility of exploring the realm of possibilities is somewhat self-defeating.
The semantic challenges of the logical positivists and their ilk are more troubling. The suggestion here is that all discussion of “possibility” and “actuality” and the like are actually discussions about our language and the concepts associated with it. For example, when we say “x is impossible,” were ultimately arriving at a similar finding as a “married bachelor” being impossible. If possibility is ultimate grounded in linguistic conventions, metaphysics can’t be said t be investigating “reality” in any powerful sense.
A problem here though is that there is a perfectly good way in which, for example, a bachelor could be married, and it involved bringing in a little something called reality. The referent of an utterance of “bachelor” at t=0 may no longer be accurately described as a bachelor at t=1. Furthermore, linguistic conventions can and do change, sometimes deliberately. There is little historical reason to believe that metaphysics is reducible solely to an investigation of the structure of language.
Here I hope to have shown that metaphysics, conceived as an inescapable/universal discipline of a not-wholly-empirical character concerned with investigating the nature of ultimate reality, is not only possible but inescapable. Any supposed external status skepticism of metaphysics constitutes a conventional metaphysical theory, and thus undermines itself.
Rational A Priori 