Over the recent years, the pursuit of scientific metaphysics has become a central enterprise in the philosophy arena. Issues about the nature of metaphysical research, the scope of metaphysical knowledge, and the role of metaphysics within the human Enlightenment project of the sciences have rapidly experienced a vivid renaissance. The volume under review undoubtedly presents an outstanding, cutting-edge contribution to this debate, and it may well be considered as the most comprehensive and philosophically penetrating book of its kind.
The volume is comprised of ten independent papers. Contributors are Anjan Chakravartty, Daniel Dennett, Michael Friedman, Paul Humphreys, Jenann Ismael, Harold Kincaid, James Ladyman, Andrew Melnyk, Don Ross, and Mark Wilson. Among the main issues addressed are the state of art of scientific metaphysics (Chapter 1), problems regarding the prospects of naturalized metaphysics (Chapter 2), the critique of speculative ontology (Chapter 3), analysis of the naturalization project (Chapter 4), the bestiary of the manifest image (Chapter 5), the structural realist interpretation of quantum mechanics (Chapter 6), the influence of the scientific philosophy heritage on the contemporary debate (Chapter 7), the relativised Kantian-style conception of scientific rationality (Chapter 8), remarks on naturalism (Chapter 9), and the place of free will within scientific ontology (Chapter 10).
Throughout this review, I examine three core issues: first, problems resulting from the viability of scientific metaphysics; second, the critique of a priori analytic metaphysics; and third, a new positive attempt to pursue a scientific metaphysics. As a whole, this strategy will give us a fairly comprehensive view of the state of art of the discussion.
Let us begin with the first of these issues. Scientific metaphysicians contend that metaphysical research should take science seriously. At present, almost everyone would agree on this. Nonetheless, as Chakravartty observes, it is hard to develop in detail this general idea. What exactly does it mean for a metaphysician to take science seriously? Assuming that both science and metaphysics aim to know the nature and structure of reality, and given the overwhelming success of scientific research when compared with metaphysical research, the question takes the form of how to constrain the latter with the practices and standards of rationality and understanding of the former. Thus, even though the book as a whole attempts to provide several approaches to answer this question, Chakravartty’s worries about the viability and even the possible failure of achieving scientific metaphysics truly point to a genuine philosophical concern.
Chakravartty initiates his analyses by describing what he calls the slippery slope, i.e. the quest of philosophers of science for the metaphysical underpinnings of scientific theorizing. A clear example of this is the metaphysical speculation about the causal powers involved in gene transcription processes as described by cell and tissue biology (38). Naturalistic metaphysicians will certainly avoid going down the slippery slope of speculative metaphysical theorizing, since this would be too far removed from scientific detail. However, there is no reasonable determination of where to stop on the slippery slope.
Things get worse when it is noticed that both a priori analytic metaphysics and scientific metaphysics differ not in their aim, but in their method. Scientific metaphysics demarcates itself from a priori analytic metaphysics by appealing to proximity to scientific context or to be connected with scientific research (33). This, Chakravartty contends, is “intuitively compelling but largely empty” (30), since it relies on a caricature of the sciences, which are “commonly described as a posteriori investigations whose outputs are empirically testable” (33). There are sciences that do not actually make empirical predictions (evolutionary biology), experiments (string theory), or successful manipulation of things (cosmology) (33). According to Chakravartty, apart from the caricature of science, scientific metaphysics also depends upon the assumptions of scientific progress and naturalism (39), and neither of them has been fairly settled on the discussion.
He goes further by emphasizing the incoherence of the naturalization project (40–43). We need a good argument to account for the continuity of scientific metaphysics and the sciences. Expressions such as “derived from”, “based on”, “inspired by”, “motivated by”, “constrained by”, and “restricted to” the sciences (40 and 47) do not do the work. Interestingly, Chakravartty advances two criteria for assessing continuity, viz., experiential distance of an object of inquiry and theoretical risk measured by how susceptible a hypothesis is to disconfirmation. However, these criteria leave open both the questions of the slippery slope and the demarcation between a priori analytic metaphysics and scientific metaphysics. Chakravartty says that he is optimistic about the prospects of scientific metaphysics (46), even though he concludes that: first, it does bring up a priori considerations of the underlying features of entities and process of scientific discourse; second, it applies criteria of consistency, coherence, scope, simplicity, etc., just like a priori analytic metaphysics; and third, it marshals intuitions about the preference on these desiderata in assessing the strength and weakness of metaphysical hypothesis and in deciding which phenomena are worth to be explained (48–49).
In sum, Chakravartty clearly shows three genuine philosophical concerns, viz., there is no definite stop-point while going down on the slippery slope; the distinction between a priori analytic metaphysics and scientific metaphysics is unclear; and it is problematic how proximate the latter should be to scientific research.
However, we can still argue that the failure of a priori analytic metaphysics to be part of the quest for objective knowledge brings on a non-negotiable reason to keep looking for a scientific metaphysics. Let us then examine our second issue, viz., the critique of a priori analytic metaphysics, as it has been carried out over the second half of the twentieth century.
Van Fraassen (2002, Lecture 1), Ladyman et al. (2007, Chapter 1), and Maudlin (2007, Introduction and Epilogue) have previously advanced demolishing critiques of a priori analytic metaphysics. Along the present volume, the critique follows a similar path. Kincaid, for instance, maintains that analytic metaphysics is considered as “a questionable enterprise because of its lack of scientific standing” (1), while, in the same vein, Melnyk goes straight to the point by describing the situation as follows: given that non-naturalized metaphysics “has been pursued for a very long time without yielding results at all comparable with those achieved by mathematics and logic” (80–81), metaphysics ought to be naturalized—although, according to him, how this can be accomplished remains still as a problem. Furthermore, throughout the book, there is a general consensus about the failure of a priori analytic metaphysics to belong to the human Enlightenment project of the quest for objective knowledge. The reader can confirm this by consulting the following passages: Kincaid (1, 3), Melnyk (80), Dennett (97), Ladyman and Ross (109), Wilson (151), and Ismael (231 and 234), among others.
Looking into the possibility of properly developing metaphysical enquiry, Humphreys’ contribution finely articulates what we can call the standard critique of speculative ontology, which I take to be the ontology of a priori analytic metaphysics. Even though disagreements among metaphysicians usually regard what there is and what there is not, the question at issue here is primarily related to the problem of what the method of metaphysics should or should not be. In this respect, he examines, first, the factual falsity of theories in analytic metaphysics; second, the use of unreliable a priori epistemic tools, such as intuition, conceptual analysis, and philosophical idealizations; and third, the methodological assumption of ontological scale invariance. I will briefly outline the second case because it is particularly illustrative when it comes to the critique of the methods employed by a priori analytic metaphysicians.
Firstly, Whose intuitions are to be considered? The increasing consensus on this matter shows that a priori intuitions cannot be used as evidence for metaphysical theories. There are at least four problems: first, metaphysicians widely disagree with respect to what intuitions we should accept or even argue for; second, intuitions are usually wrong when they are meant to refer to something which goes beyond ordinary experience; third, the epistemic reliability of intuitions is always context- and agent-dependent; and four, we simply do not know how metaphysicians can be trained to improve both their intuitions and their ability to identify successful a priori intuitions (58–62).
Secondly, regarding conceptual analysis (62–64), Humphreys maintains that it certainly plays a legitimate role in the elaboration of scientific ontology, but when it is applied to metaphysics, it does not contribute new knowledge of reality. On one hand, in metaphysics, there is an evident lack of fine-grained, sharply defined linguistic resources. As a matter of fact, in metaphysics, there is not a conceptual apparatus that informs a universal code delivering knowledge of some of the multiple aspects of reality, as it is currently revealed through scientific research. On the other, conceptual analysis is naturally limited to the domains in which we have evolved as restricted epistemic experts. Among other things, this explains why metaphysical concepts are generally drawn from ordinary experiences, relying on common sense views of reality and without fitting across all intuitive cases.
And thirdly, philosophical idealizations differ from, for instance, mathematical idealizations. While the latter make use of their ability to picture or map reality by employing a well-established, universally applied notation, such as numbers, sets, and functions, plus clearly defined operation rules, the former, by contrast, usually overuses metaphors and extrapolates reality to the extreme without any precise criteria of reference to reality. Indeed, there is no generally accepted answer to the question of what a legitimate philosophical idealization would be like. Familiar examples are the ideal limit of scientific enquiry, the extrapolation of human epistemic abilities, and the appeal to the perfection of God in the ontological argument (66–68). To the list, we can add the overuse of possible worlds, counterfactuals, and zombie-like problems. In none of these cases, philosophers have, and perhaps cannot possibly have, a clear conception of what the reality, if any, of each one of these examples would be like.
Humphreys’ contribution is probably meant to become the standard critique of a priori analytic metaphysics. However, philosophers interested in carrying out scientific metaphysics still need to look into the possibility of advancing a positive exercise in scientific metaphysics. This moves us to our third issue. Indeed, the proposal of Ladyman and Ross can be considered as properly accomplishing the task of elaborating a scientific metaphysics.
As in their previous contribution in naturalistic metaphysics (Ladyman et al. 2007), Ladyman and Ross reinforce the claim that “if metaphysics is to be part of the pursuit of objective knowledge, it must be integrated with science” (109). In this respect, scientific metaphysics works in the elaboration of a weak unification of the special sciences by reference to fundamental physics, which is understood as the branch of physics whose theories can be explicitly or implicitly tested by measurements taken at any scale of reality and in any region of the universe. The unification is weak because it is not reductionist, that is, even though theories of fundamental physics constrain all special sciences, it does not capture all scale-relative, real patterns of special sciences.
In particular, Ladyman and Ross advance a structural realist interpretation of quantum mechanics, which proposes a strong ontological view of reality as irreducibly stochastic. This proposal intends to meet metaphysical challenges currently resulting from quantum mechanics. On one hand, from a philosophical perspective, they suggest that there are two ways for metaphysicians to address ontological problems, namely: first, answering the question of which entities scientists should be construed as really believing in; and second, investigating the fundamental structure of the world. On the other hand, from a scientific perspective, they hold the idea that quantum mechanics is the only currently mature part of science, which is reasonably intended to restrict all possible measurement values in the universe at all scales (131–132). In this scenario, structural realist metaphysicians can directly deal with problems about the fundamental structure of reality by seriously addressing metaphysical conundrums of quantum mechanics, such as systems in superposition with respect to observables and the measurement problem.
Inspired by Peirce’s ideas on hypothesis, laws of nature, and psychophysics, the structural realist interpretation of quantum mechanics adopts a strong philosophical stance on some perennial ontological questions. Peirce’s notion of hypothesis is interpreted as a procedure that yields explanation and a qualitative amplification of knowledge. More specifically, hypothesis is understood as a generalization worth further investigation because it structures ontologies of sample-generating processes of which we then can compute frequency distribution of variables we want to predict or control (142). In Peirce’s view, laws of nature are understood as part of a permanent structural change. Insofar as laws of nature—and nature itself—evolve from chance, their constants of reference are not fixed, but evolving. Indeed, the access we have to them is statistically stochastic (144). Finally, with respect to the third, Peirce’s interest in psychophysics encouraged him to reinterpret properties of frequencies not as second-order properties of judgments, but instead as basic properties of the external world that constitute its structure (144–145).
Even though Ladyman and Ross do not go further into the Peircean scholarship, they remarkably accomplish the task of showing one of the multiple philosophically insightful aspects of Peirce’s view of reality. In the present case, this is exemplified in its current systematic relevance for discussions on the metaphysics of science. In short, the Peircean framework, along with an up-to-date scientific and philosophical knowledge of the matter, allows Ladyman and Ross to put forward their proposal of an irreducibly stochastic nature of reality. In one of their different formulations, they maintain that the world is the totality of non-redundant statistical data, namely the endless wave of patterns that science will go on uncovering forever as long as we pursue scientific research (148).
I close with two philosophical remarks. The first regards the following question: Are there any minimal desiderata on which philosophers pursuing scientific metaphysics should agree? In my understanding, there is an important agreement on the philosophical stance behind the scientific metaphysics project. This can be characterized by the following desiderata, which I propose should be accepted as operating on every metaphysical theorizing that works hand in hand with the sciences:
Epistemic desideratum: scientific metaphysics rejects the appeal to some forms of a priori epistemic tools, such as intuition, conceptual analysis, and philosophical idealizations. By contrast, it accepts mathematical modelling and mathematical idealization, empirical testing, statistical analysis of data, predictions, and manipulation, as more reliable epistemic tools.
Methodological desideratum: scientific metaphysics acknowledges that scientific methods are our best guide to the knowledge of reality. At a minimum, the methodological procedure employed in metaphysics must cohere with, and in no case contradict, scientific methodologies. Needless to say that both scientific and metaphysical theories should be assessed according to similar criteria to decide whether they are to be provisionally accepted or outright rejected.
Ontological desideratum: scientific metaphysics recognizes that our currently bona fide scientific theories are the best account that we have of the furniture of reality. There is no fundamental metaphysical realm. In particular, metaphysics should contribute to the understanding of our scientific worldview and in no case to inflate it with non-scientifically motivated spooky entities.
These desiderata give us a clear preliminary idea of the philosophical stance behind scientific metaphysics, restrengthening the necessity to demarcate this project from the mere speculations of a priori analytic metaphysics.
The second remark regards this question: Can scientific metaphysics still be considered philosophy? Ross (2012) has previously examined this issue. As things go, it seems that we should not expect metaphysics bring about independently well-grounded, philosophical theories of reality without the sciences being taking seriously into consideration. Instead, scientific metaphysics, facing the so far unavoidable instability of a priori analytic metaphysics, is welcome to put metaphysical theorizing to the service of the sciences. Metaphysicians, I think, should not regret this: as a matter of fact, both theoretical and empirical sciences happen to be the best account that we have of the nature and structure of reality. On the contrary, in this scenario there is yet a positive task to be done by metaphysicians, namely to examine the boundaries of a scientific ontology and to elaborate a scientific view of reality.
On a wider scope, if we expect scientific metaphysics to positively replace the so far unsuccessful a priori analytic metaphysics, then philosophers carrying out scientific metaphysics should come up with an answer to questions like these: Is there genuine metaphysical knowledge? Does metaphysics have a particular research framework along with a specific methodology? Is metaphysics to be considered as merely belonging to our anthropologically oriented arts and humanities? Or is it instead a form of objective, truth-conducive theoretical science?
The editors of the volume have achieved a significant contribution in putting these papers together in a book that can be recommended to metaphysicians, philosophers of science, and scientists themselves. They all can contribute today to the assessment of a discipline that is on the borderline of being considered as either useless or essential to the pursuit of objective knowledge of reality.
Ladyman, James, Don Ross, David Spurret, and John Collier. 2007. Everything must go. Metaphysics naturalized. Oxford: Oxford University Press.
Maudlin, Tim. 2007. The metaphysics within physics. Oxford: Oxford University Press.
Ross, Don. 2012. Will scientific philosophy still be philosophy? Academia.edu. http://www.academia.edu/948847/Will_scientific_philosophy_still_be_philosophy. Accessed 20 May 2013. Forthcoming in Recherches sur la philosophie et le langage.
Van Fraassen, Bas. 2002. The empirical stance. New Haven: Yale University Press.
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Soto, C. The aim and scope of scientific metaphysics. Metascience 23, 117–123 (2014). https://doi.org/10.1007/s11016-013-9822-2