CONTINUITY AND DISCRETENESS BETWEEN SCIENCE AND METAPHYSICS

RESEARCH PROGRAM

METHAPHYSICS AND THE A PRIORI/A POSTERIORI DISTINCTION

University Co-ordinator
Università degli Studi di URBINO "Carlo BO" - Filosofia

Description

We will try to shed light on differences and analogies between physics and metaphysics from the point of view of the relationships among experience, models and reality, along some of the directions described in the state of the art.
The relation between theory and reality will be examined to begin with from a general ontological viewpoint. The complexity of the world requires a pluralistic approach, envisaging different models for different epistemic situations: sometimes individuals are enough, in other cases continuums or totalities must also be considered. According to Aristotle being may be predicated in many senses, as many as the categories, but related to the unique and fundamental sense of substance (Metaph. IV 1); so metaphysics too should be practiced in many ways.
Venanzio Raspa will compare Frege's approach, where the world consists of individuals, properties and relations, with Meinong's and Peirce's theories, cooperating as in the past with Francesco Orilia (2005) of the Macerata research unit. Meinong keeps individuals, but classifies the objects in a way that explains not only the physical aspects, but also the psychic and ideal aspects of the world (for instance, mathematical entities and the products of fantasy). Thus, beside individuals he countenances impossible objects (which arose so many discussions in the past century) "objectives", or state of things (today the subject of a debate whith those who prefer tropes) spatial and temporal continuums.
The latter concept will be examined also in the contemporary work of Peirce. By relying on Aristotele, Kant, Dedekind and Cantor, Peirce defines the mathematical continuum in terms of density, compactness and sectionability, and gives it an ontological application through the Stoic concept of existence. He defines continuum as what reacts both against the external world and against the subject: a continuum does not exist by itself, but in a spatio-temporal context and in a web of relationships. The space-temporal context is the "phenomenological context", it is the background against which emerges the picture, or the object.
The problem of temporal continuity of objects will be dealt with by Domenico Mancuso, by considering Peirce's and Ryle's (1945) hypothesis of a irreducibly general ontological statute of future objects, and Mayo's (1962) hypothesis of instant existence of objects, now known as sequentialism. In order to explain the emotional ties of conscious individuals to past and future, he will consider the option to ground the diachronic unity of individuals on self-consciousness; subsequently he will consider the alternative solution of the potential continuity of individuals: there are invariant properties in the temporal evolution of the individual, although they cannot be identified apart from such evolution. Finally, he will examine the possible extension of potential continuity to generic objects, and the possible asymmetries between past and future objects
An individual's context, however, is not only the spatio-temporal (or phenomenological) one, but also that of the relationships which it has, based on its properties, with a net or field of objects, which may not be perceptually accessible ("dialectic context"). Hence, different objects in the same phenomenological context may belong to different dialectical contexts. Moreover any object, depending on its properties, is related to other objects, hence determining a "totality", or "portion of the world". This is obviously true of continuums, which Raspa e Mancuso will analyze as situated in phenomenological or dialectical contexts.
In considering whether physics and metaphysics differ from the standpoint of the relations between models and reality, we shall ask whether physical theories have a merely empirical content, as held by antirealists, or also an ontological scope, as scientific realists believe. Mario Alai has already dealt with this question in the past (Alai 2005, 2006), that the constraints of experience over models are such that we may consider theories as on the one hand grounded on experience, and on the other hand as at least approximately faithful to reality. Within the present project he will develop those researches by discussing some aspects of the contemporary debate on scientific realism, especially as opposed to Van Fraassen's constructive realism.
The goal is probing the so called "no-miracle argument" of Boyd (1983), Putnam (1978), and others, by asking if the realist hypothesis can be confirmed by experience (i.e., by the success of theories). Various objections by (van Fraassen (1980), Ghins (2002), etc.) will be considered. One of the most important was advanced by Laudan (1981b), and newly argued by Lyons (2002). According to Laudan falsification of most past theories, included the empirically successful ones, blocks the attempt to explain success by the truth of theories. In fact, this is just a new version of the antirealists arguments based on scientific revolutions (Kuhn 1962) and on the consequent "pessimistic meta-induction" (Putnam 1978). We shall ask whether these objections can be stalled by "deployment realism" (Kitcher 1993, Psillos 1999), according to which we often can isolate some true claims within false theories as an explanation of their empirical success. But we shall have to deal with Lyon's paper, claiming that in many historical cases (such as Rankine's thermodynamics) a number of empirically confirmed predictions have been deduced from false components. If so, deployment realism is doomed, but a problem is left open: for one cannot claim that the truth of some empirical consequences of models is explained by the falsity of the theoretical claims from which they were deduced. The whole question must then be examined in detail and in relation to the case studies involved. Here Alai will cooperate with collegues of our research unit (Fano, Afriat e Tarozzi on the problems of theoretical physics, Tassani on historical problems, De Palma on epistemological aspects), and other scholars in Italy (Massimo Dell'Utri of the Sassari unit) and abroad (Michel Ghins of Lovain-la-neuve), who have already debated these questions with him.
From the point of view of the relations between experience and models, Enzo Fano has studied (1996, 2002) how to physical theories relate to perceptual experience. Now he will focus on how this relation changes when passing from the phenomenological physics of the ancients to modern mathematical and abstract physics, to contemporary physics, in some ways more analogous to pre-theoretic experience. With the help of De Palma, and in connection with Alai's work on realism, he will try to give an exact account of the reality criteria for theoretical models emerging from sense experience.
A touchstone for these discussions is offered by the physical and metaphysical nature of space-time: this will be a common topic for the whole unit, on which Raspa's work on continumm, Mancuso's study of diachronic continuity, and Afriat's research (see below) will also converge. The old metaphysical debates on the substantial vs. merely relational nature of space and time (such as the Leibniz-Clarke debate), which are obviously grounded first of all on perceptual and pre-theoretic experience (see Giannini 2006), today are confronted with the findings of relativistic cosmology, as discussed in (Fano, Tassani 2002) and (Macchia 2006); on the former connection Fano will work especially with Giulia Giannini and Vittorio De Palma, who has studied the "phenomenological analysis of science" (2001) and the "phenomenological constitution of scpace" ("La costituzione fenomenologica dello spazio", in print). On the former connection Fano will cooperate with Giovanni Macchia e Alexander Afriat.
In particular, Afriat will move from the idea that the reality of gravitational waves and the cosmological constant support Newton and the substativists, while complicate matters for Leibniz, Mach and their followers. Machians would like to claim that "matter (i.e. the stress-energy tensor T) determines spacetime geometry". But T determines the Einstein tensor, more or less determines Ricci tensor, and underdetermines Riemann tensor. The crucial point is that many Riemann tensors correspond to the same T. The Machian has to argue that the mathematical freedom (in Riemann tensor with respect to T) is illusory, merely mathematical. The substantivist, in turn, would have to claim that the overdetermination is physically significant, not just empty mathematics.
Is the underdetermination physical? Are gravitational waves real? We have yet to discover them experimentally. In principle they contribute to the "guidance" (Weyl speaks of Fuehrung) of massive objects, and could do a number of other things (Earman speaks of lightbulbs, boiling water etc.). If there were a decent law of conservation of energy in general relativity, one could argue that as binary stars lose kinetic energy as they spiral inwards around their common centre, the lost energy gets "radiated" in the form of gravitational waves (in fact, Hulce and Taylor won a Nobel prize using this argument). The trouble is that there isn't a decent conservation law, because the covariant derivative isn't integrable, etc.
Summing up: a genuine experimental discovery of gravitational waves would certainly favour Newton (i.e. spacetime substantivism), as would a satisfactory conservation law. One must remember that Leibniz spoke of the identity of indiscernibles: as long as gravitational waves are empirically indistinguishable from their absence, the relationist Machian can always claim that the effective geometry is completely determined by matter (T) (Hoefer 1996, 1998, 2000; Weinberg 1972).
The cosmological constant can also be determined empirically, and (a nonvanishing value) would also favour Newton, Earman etc.. In the absence of matter (T vanishes identically) the cosmological constant gives (empty) spacetime nonvanishing curvature, and hence causal powers: an intrinsic power to separate and accelerate objects which would be difficult to account for in purely relationist terms. It is as though the momentum gained by the objects came out of nowhere. All this apparently shows that even metaphysical problems may be discussed a posteriori, and even experimentally. If this sounds somehow surprising, it should be noticed that some of us (Tarozzi, Fano, Tassani, Giannini) have studied in various ways the connections between the conceptual structures of contemporary theories of physics and their hidden metaphysical presuppositions. More precisely, they analyzed the observer's role in quantum measurement (Tassani, 2004; Fano, Tassani, 2007; Tarozzi, Tassani, 2001; Tassani, 2005, 2005a, 2006) and the presuppositions of relativistic theories, with particular concern to time and space (Fano, Tassani, 2002; Fano, Minazzi, Tassani, 2007, Fano, Tassani, 2007; Tassani, 2002; Tarozzi, Tassani, 2007, Giannini 2006).
In particular, Tarozzi worked on metaphysical theses as empirically and theoretically equivalent interpretations of the mathematical structures of physics, and as conceptual presuppositions or definitions involved by science (Tarozzi 1988). In a number of articles he has shown that the metaphysics implicit in physical theories may be subjected to experimental tests and thus be confirmed, or disconfirmed, or found empty and irrelevant, or relevant and endowed with physical content. In particular, he has stressed the fundamental role of the reality principle of Einstein Podolsky Rosen (1935. Henceforth: EPR) and of its subsequent probabilistic generalizations proposed by himslef as necessary conditions in the proof of Bell's theorem. He also discussed the experimental discrimination between between the realistic and the subjectivist interpretation of the wave function, the implications of the measurement paradoxes for the mind-body problem, and (in two recent papers with Afriat) the problems concerned with quantum nothing.
Within the present project he will go on by trying turn a mental experiment, proposed with Gennaro Auletta (Tarozzi, Auletta, 2004a, 2004b) and showing the incompatibility between two realistic interpetaitons of quantum mechanics (the local realism of EPR and the realistic interpretation of the wave function), into a real interferometry experiment; the latter might either refute the predictions of quantum mechanics upholding the local realism of EPR, or confirm them, but with them also a realistic interpretation of the wave function. Moreover, together with Afriat, Auletta and Fano, Tarozzi will study the possibility of a quantum computer using the interferometric apparatus of the above experiment, where Wheeler's (1978) delayed choice may take place. Originally, the latter was a non verifiable operation modifying a non recorded past event; but in our case it becomes a verifiable operation, since it may modify a recorded past event. On some of these problems Tarozzi and co-workers will debate also with Orilia of Macerata, who discussed them in (Orilia 2006).
On the other hand, Isabella Tassani will work in a mainly historic perspective, accounting for the philosophical and cultural context in which quantum mechanics was born, under the various influences of neopositivism, Lebensphilosophie, neokantism, scientific psychology and phenomenology. Contemporarily, she plans to study the impact of scientific theories on epistemology, by exploring the reactions to quantum mechanics by Popper (1982) and the "new philosophers of science" (Feyerabend, 1968, 1969; Hanson, 1958, 1959, 1963; Kuhn, 1978; Laudan, 1981a, 1990): their approach to quantum mechanics will work as a litmus paper for a better understanding both of their epistemologies and of the underlying metaphysical conceptions.