Grades of individuality. A pluralistic view of identity in quantum mechanics and in the sciences

This paper offers a critical assessment of the current state of the debate about the identity and individuality of material objects. Its main aim, in particular, is to show that, in a sense to be carefully specified, the opposition between the Leibnizian ‘reductionist’ tradition, based on discernibility, and the sort of ‘primitivism’ that denies that facts of identity and individuality must be analysable has become outdated. In particular, it is argued that—contrary to a widespread consensus—‘naturalised’ metaphysics supports both the acceptability of non-qualitatively grounded (both ‘contextual’ and intrinsic) identity and a pluralistic approach to individuality and individuation. A case study is offered that focuses on non-relativistic quantum mechanics, in the context of which primitivism about identity and individuality, rather than being regarded as unscientific, is on the contrary suggested to be preferable to the complicated forms of reductionism that have recently been proposed. More generally, by assuming a plausible form of anti-reductionism about scientific theories and domains, it is claimed that science can be regarded as compatible with, or even as suggesting, the existence of a series of equally plausible grades of individuality. The kind of individuality that prevails in a certain context and at a given level can be ascertained only on the basis of the specific scientific theory at hand.     

Underdetermination,realism and empirical equivalence

Are theories ‘underdetermined by the evidence’ in any way that should worry the scientific realist? I argue that no convincing reason has been given for thinking so. A crucial distinction is drawn between data equivalence and empirical equivalence. Duhem showed that it is always possible to produce a data equivalent rival to any accepted scientific theory. But there is no reason to regard such a rival as equally well empirically supported and hence no threat to realism. Two theories are empirically equivalent if they share all consequences expressed in purely observational vocabulary. This is a much stronger requirement than has hitherto been recognised—two such ‘rival’ theories must in fact agree on many claims that are clearly theoretical in nature. Given this, it is unclear how much of an impact on realism a demonstration that there is always an empirically equivalent ‘rival’ to any accepted theory would have—even if such a demonstration could be produced. Certainly in the case of the version of realism that I defend—structural realism—such a demonstration would have precisely no impact: two empirically equivalent theories are, according to structural realism, cognitively indistinguishable.     

Informational Realism and World 3

This paper takes up a suggestion made by Floridi that the digital revolution is bringing about a profound change in our metaphysics. The paper aims to bring some older views from philosophy of mathematics to bear on this problem. The older views are concerned principally with mathematical realism—that is the claim that mathematical entities such as numbers exist. The new context for the discussion is informational realism, where the problem shifts to the question of the reality of information. Mathematical realism is perhaps a special case of informational realism. The older views concerned with mathematical realism are the various theories of World 3. The concept of World 3 was introduced by Frege, whose position was close to Plato’s original views. Popper developed the theory of World 3 in a different direction which is characterised as ‘constructive Platonism’. But how is World 3 constructed? This is explored by means of two analogies: the analogy with money, and the analogy with meaning, as explicated by the later Wittgenstein. This leads to the development of an account of informational realism as constructive Aristoteliansim. Finally, this version of informational realism is compared with the informational structural realism which Floridi develops in his 2008 and 2009 papers in Synthese. Similarities and differences between the two positions are noted.     

A REFUTATION OF PURE CONJECTURE

The present paper explores three interrelated topics in Popper's theory of science: (1) his view of conjecture, (2) the aim of science, and (3) his (never fully articulated) theory of meaning. Central to Popper's theory of science is the notion of conjecture. Popper writes as if scientists faced with a problem proceed to tackle it by conjecture, that is, by guesses uninformed by inferential considerations. This paper develops a contrast between guesses and educated guesses in an attempt to show that there is more to scientific conjecture than conjecture. The suggestion is made that some inductive considerations enter into the process of educated guessing or scientific conjecture in such a way that the ‘context of discovery’ cannot be sharply separated from the ‘context of justification’. This discussion leads to a tension between Popper's negative method of conjecture and his realism. Given Popper's (implicit) theory of meaning it seems Popper's epistemology (the conjecture and refutation method) is incompatible with his metaphysical realism.     

Non‐competitor Conditions in the Scientific Realism Debate

A general insight of 20th‐century philosophy of science is that the acceptance of a scientific theory is grounded, not merely on a theory’s relation to data, but on its status as having no, or being superior to its, competitors. I explore the ways in which scientific realists might be thought to utilise this insight, have in fact utilised it, and can legitimately utilise it. In more detail, I point out that, barring a natural but mistaken characterisation of scientific realism, traditional realism has not utilised that insight regarding scientific theories, i.e., has not explicitly factored that insight into, and invoked it as justification for, what realists believe. Nonetheless, a new form of realism has. In response to a key historical threat, two of the most thoroughly developed contemporary versions of realism—one put forward by Jarrett Leplin, another by Stathis Psillos—are anchored on the sensible tactic of requiring that the theories to which realists commit themselves have no competitors. I argue, however, that the particular kind of non‐competitor condition they invoke is illegitimate in the context of the realism debate. I contend further that invoking a non‐competitor condition that is legitimate, sensible, and even, as it turns out, required in the context of the debate threatens to eliminate the possibility of scientific realism altogether.     

Conventionalism,scientific discovery and the sociology of knowledge*

In this paper the basic aim of the so‐called ‘strong programme’ in the sociology of knowledge is examined. The ‘strong programme’ is considered (and rightly so) as an extreme version of the anti‐realist view of science. While the problem of scientific realism has normally been dealt with from the point of view of the ‘context of justification’ of theories, the paper focuses on the issues raised by law‐discovery. In this context Herbert Simon's views about the existence of a ‘logic of scientific discovery’ are discussed and criticized. The main thesis of the paper is that if the structure of both discovery and prediction is properly understood, then the basic anti‐realist claims become untenable. A fortiori, the ‘strong programme’ appears to be unable to explain some basic features of the structure of science.     

Kant on Recognizing Beauty

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Reality in science

One way in which to address the intriguing relations between science and reality is to work via the models (mathematical structures) of formal scientific theories which are interpretations under which these theories turn out to be true. The so-called ‘statement approach’ to scientific theories—characteristic for instance of Nagel, Carnap, and Hempel—depicts theories in terms of ‘symbolic languages’ and some set of ‘correspondence rules’ or ‘definition principles’. The defenders of the oppositionist non-statement approach advocate an analysis where the language in which the theory is formulated plays a much smaller role. They hold that foundational problems in the various sciences can in general be better addressed by focusing on the models these sciences employ than by reformulating the products of these sciences in some appropriate language. My model-theoretic realist account of science lies decidedly within the non-statement context, although I retain the notion of a theory as a deductively closed set of sentences (expressed in some appropriate language). In this paper I shall focus—against the background of a model-theoretic account of science—on the approach to the reality-science dichotomy offered by Nancy Cartwright and briefly comment on a few aspects of Roy Bhaskar's transcendental realism. I shall, in conclusion, show how a model-theoretic approach such as mine can combine the best of these two approaches.     

Perspectivism Versus a Completed Copernican Revolution

I discuss changes of perspective of four kinds in science and about science. Section 2 defends a perspectival nonrealism—something akin to Giere’s perspectival realism but not a realism—against the idea of complete, “Copernican” objectivity. Section 3 contends that there is an inverse relationship between epistemological conservatism and scientific progress. Section 4 casts doubt on strong forms of scientific realism by taking a long-term historical perspective that includes future history. Section 5 defends a partial reversal in the status of so-called context of discovery and context of justification. Section 6 addresses the question of how we can have scientific progress without scientific realism—how progress is possible without the accumulation of representational truth. The overall result (Sect. 7) is a pragmatic instrumentalist perspective on the sciences and how to study them philosophically, one that contains a kernel of realism—instrumental realism.     

Re-enchanting Realism in Debate with Kyle Stanford

In this article, against the background of a notion of ‘assembled’ truth, the evolutionary progressiveness of a theory is suggested as novel and promising explanation for the success of science. A new version of realism in science, referred to as ‘naturalised realism’ is outlined. Naturalised realism is ‘fallibilist’ in the unique sense that it captures and mimics the self-corrective core of scientific knowledge and its progress. It is argued that naturalised realism disarms Kyle Stanford’s anti-realist ‘new induction’ threats by showing that ‘explanationism’ and his ‘epistemic instrumentalism’ are just two positions among many on a constantly evolving continuum of options between instrumentalism and full-blown realism. In particular it is demonstrated that not only can naturalised realism redefine the terms of realist debate in such a way that no talk of miracles need enter the debate, but it also promises interesting defenses against inductive- and under-determination-based anti-realist arguments.     

The EPR-Experiment and Free Process Theory

As part of the ‘creation-discovery’ interpretation of quantum mechanics Diederik Aerts presented a setting with macroscopical coincidence experiments designed to exhibit significant conceptual analogies between portions of stuff and quantum compound entities in a singlet state in Einstein—Podolsky—Rosen/Bell-experiments (EPR-experiments). One important claim of the creation-discovery view is that the singlet state describes an entity that does not have a definite position in space and thus ‘does not exist in space’. ‘Free Process Theory’ is a recent proposal by Johanna Seibt of an integrated ontology, i.e., of an ontology suitable for the interpretation of theories of the macrophysical and microphysical domain (quantum field theory). The framework of free process theory allows us to show systematically the relevant analogies and disanalogies between Aerts' experiment and EPR-experiments. From free process ontology it also follows quite naturally that the quantum compound entity described by the singlet state ‘does not exist in space.’     

Platonism and anti‐Platonism: Why worry?

This paper argues that it is scientific realists who should be most concerned about the issue of Platonism and anti‐Platonism in mathematics. If one is merely interested in accounting for the practice of pure mathematics, it is unlikely that a story about the ontology of mathematical theories will be essential to such an account. The question of mathematical ontology comes to the fore, however, once one considers our scientific theories. Given that those theories include amongst their laws assertions that imply the existence of mathematical objects, scientific realism, when construed as a claim about the truth or approximate truth of our scientific theories, implies mathematical Platonism. However, a standard argument for scientific realism, the ‘no miracles’ argument, falls short of establishing mathematical Platonism. As a result, this argument cannot establish scientific realism as it is usually defined, but only some weaker position. Scientific ‘realists’ should therefore either redefine their position as a claim about the existence of unobservable physical objects, or alternatively look for an argument for their position that does establish mathematical Platonism.     

Lessons from realistic physics for the metaphysics of quantum theory

Quantum mechanics, and classical mechanics, are framework theories that incorporate many different concrete theories which in general cannot be arranged in a neat hierarchy, but discussion of ‘the ontology of quantum mechanics’ tends to proceed as if quantum mechanics were a single concrete theory, specifically the physics of nonrelativistically moving point particles interacting by long-range forces. I survey the problems this causes and make some suggestions for how a more physically realistic perspective ought to influence the metaphysics of quantum mechanics.

     

Why Evolution is Really Indeterministic

Leslie Graves, Barbara Horan and Alex Rosenberg (1999) have argued that the process of evolution is really deterministic, so we should be instrumentalists about our probabilistic evolutionary theory. I criticize the consistency of their view. I argue that because they are realists towards multiple theories (quantum mechanics and macrophysics) their arguments against realism for another scientific theory fail. The main point of this paper is critical, but in order to set up this criticism I explore the ramifications of realism for multiple theories. Finally, I offer a brief metaphysical justification for realism about multiple theories. This view justifies realism for evolutionary theory, which has been defended by Robert Brandon and Scott Carson (1996).     

Perspectival Realism and Incompatible Models

I discuss the prospects of perspectival realism for resolving the problem of incompatible models or theories in scientific practice. My diagnosis is that the perspectivist can secure the ‘realism’ in her position only by employing suitable relations between the models. It is such relations that do the work, not the general philosophical claim about the perspectival nature of knowledge claims. But appeal to such relations has also been the preferred strategy of scientific realist approaches to the problem. With respect to the problem of incompatible models, then, it is not clear that perspectivism has a clear advantage—even though the issue was among the motivating problems for proposing this view. I suggest, however, that the required inter-model relations (typically limit relations) embody a narrower notion of perspective, a notion that is explicitly part of the models themselves and that is essential in maintaining a realist view.     

What do our critical practices say about the nature of morality?

A prominent argument for moral realism notes that we are inclined to accept realism in science because scientific inquiry supports a robust set of critical practices—error, improvement, explanation, and the like. It then argues that because morality displays a comparable set of critical practices, a claim to moral realism is just as warranted as a claim to scientific realism. But the argument is only as strong as its central analogy—and here there is trouble. If the analogy between the critical practices of science and morality is loosely interpreted, the argument does not support moral realism—for paradigmatically constructivist discourses like fashion display the relevant critical practices just as well. So if the argument is to have force, the realist must say more about why the critical practices of morality are sufficiently like those of science to warrant realism. But this cannot be done—moral inquiry differs from scientific inquiry in too many important ways. So the analogy with the critical practices of science fails to vindicate moral realism. But there are further lessons: in looking closely at the critical practices of our moral discourse—and in comparing them to the critical practices of science and fashion—we gain insight into what is distinctive about morality objectivity and moral metaphysics.     

Semantic approaches in the philosophy of science

In this article I give an overview of some recent work in philosophy of science dedicated to analysing the scientific process in terms of (conceptual) mathematical models of theories and the various semantic relations between such models, scientific theories, and aspects of reality. In current philosophy of science, the most interesting questions centre around the ways in which writers distinguish between theories and the mathematical structures that interpret them and in which they are true, i.e. between scientific theories as linguistic systems and their non-linguistic models. In philosophy of science literature there are two main approaches to the structure of scientific theories, the statement or syntactic approach—advocated by Carnap, Hempel and Nagel—and the non-statement or semantic approach—advocated, among others, by Suppes, the structuralists, Beth, Van Fraassen, Giere, Wójcicki. In conclusion, I briefly review some of the usual realist inspired questions about the possibility and character of relations between scientific theories and reality as implied by the various approaches I discuss in the course of the article. The models of a scientific theory should indeed be adequate to the phenomena, but if the theory is ‘adequate’ to (true in) its conceptual (mathematical) models as well, we have a model-theoretic realism that addresses the possible meaning and reference of ‘theoretical entities’ without relapsing into the metaphysics typical of the usual scientific realist approaches.