El propósito del presente trabajo consiste en abordar la pregunta por la ontología de la química cuántica. Para ello nos concentraremos en el concepto de enlace químico desde la perspectiva de los dos enfoques a través de los cuales la ecuación de Schrödinger se aplica a los sistemas químicos moleculares: la teoría del enlace de valencia (EV) y la teoría del orbital molecular (OM). Sobre la base de la presentación de ambos enfoques y su comparación, señalaremos que, a pesar de (...) su denominación tradicional, no pueden considerarse estrictamente como teorías científicas, sino que se ajustan mejor a la noción de modelo; en particular, son modelos que incorporan conceptos y leyes tanto del ámbito de la mecánica cuántica como del de la química estructural. Estas consideraciones nos permitirán argumentar que la química cuántica no posee un referente ontológico autónomo, sino que se trata de un ámbito científico cuya vigencia descansa sobre su éxito práctico en el cálculo y la predicción. Finalmente, indicaremos de qué modo los enfoques EV y OM del enlace químico abren una nueva perspectiva respecto de la noción misma de modelo en ciencias empíricas. (shrink)

In this paper we will address the problem of the existence of orbitals by analyzing the relationship between molecular chemistry and quantum mechanics. In particular, we will consider the concept of orbital in the light of the arguments that deny its referring character. On this basis, we will conclude that the claim that orbitals do not exist relies on a metaphysical reductionism which, if consistently sustained, would lead to consequences clashing with the effective practice of science in its different branches.

In the problem of the relationship between chemistry and physics, many authors take for granted the ontological reduction of the chemical world to the world of physics. The autonomy of chemistry is usually defended on the basis of the failure of epistemological reduction: not all chemical concepts and laws can be derived from the theoretical framework of physics. The main aim of this paper is to argue that this line of argumentation is not strong enough for eliminate the idea of (...) a hierarchical dependence of chemistry with respect to physics. The rejection of the secondary position of chemistry and the defense of the legitimacy of the philosophy of chemistry require a radically different philosophical perspective that denies not only epistemological reduction but also ontological reduction. Only on the basis of a philosophically grounded ontological pluralism it is possible to accept the ontological autonomy of the chemical world and, with this, to reverse the traditional idea of the ‘superiority’ of physics in the context of natural sciences. (shrink)

An Aristotelian philosophy of nature rejects the modern prejudice in favor of the microscopic, a rejection that is crucial if we are to penetrate the mysteries of the quantum world. I defend an Aristotelian model by drawing on both quantum chemistry and recent work on the measurement problem. By building on the work of Hans Primas, using the distinction between quantum and classical properties that emerges in quantum chemistry at the thermodynamic or continuum limit, I develop a new version of (...) the Copenhagen interpretation, a version that is realist, holistic, and hylomorphic in character, allowing for the attribution of fundamental causal powers to human observers and their instruments. I conclude with a critique of non-hylomorphic theories of primitive ontology, including Bohmian mechanics, Everettianism, and GRW mass-density. (shrink)

Chemistry deals with substances and their transformations. School chemistry provides a picture of this in terms of small balls called atoms and ball-and-stick structures called molecules which, despite its crudity, has been taken to justifiably reflect a reductionist conception of macroscopic concepts like the chemical substances and chemical reactions. But with the recent interest in chemistry within the philosophy of science, an extensive and determined criticism has developed of the idea that the macroscopic world has been, or is likely to (...) be, reduced to microscopic theory. From this perspective, it is of interest to see macroscopic ontology treated autonomously. I try to take a first few steps towards spelling this out. It involves recognising entities falling into two broad categories: continuants-things which can have different properties at different times — and processes — things whose temporal parts may have different features, but which themselves stand in contrast to continuants in this respect. The character of each and their interrelations depends on their mereological structure of parts, the exploration of which is one of the prime purposes of the paper. (shrink)

The paper addresses a problem for the unification of quantum physics with the new Aristotelianism: the identification of the members of the category of substance. I outline briefly the role that substance plays in Aristotelian metaphysics, leading to the postulating of the Tiling Constraint. I then turn to the question of which entities in quantum physics can qualify as Aristotelian substances. I offer an answer: the theory of thermal substances, and I construct a fivefold case for thermal substances, based on (...) the irreversibility of time, the definition of thermodynamic concepts, spontaneous symmetry breaking, phase transitions, and chemical form. (shrink)

Despite all the criticism showered on Nagel’s classic account of reduction, it meets a fundamental desideratum in an analysis of reduction that is difficult to question, namely of providing for a proper identification of the reducing theory. This is not clearly accommodated in radically different accounts. However, the same feature leads me to question Nagel’s claim that the reducing theory can be separated from the putative bridge laws, and thus to question his notion of heterogeneous reduction. A further corollary to (...) the requirement that all the necessary conditions be incorporated in an adequate formulation of the putative reducing theory is that the standard example of gas temperature is not reducible to average molecular kinetic energy. As originally conceived, Nagel’s conception of reduction takes no account of approximate reasoning and this failure has certainly restricted its applicability, perhaps to the point of making it unrealistic as a model of reduction in science. I suggest approximation can be accommodated by weakening the original requirement of deduction without jeopardizing the fundamental desideratum. Finally, I turn to briefly consider the idea sometimes raised of the ontological reducibility of chemistry. (shrink)

The aim of the present paper is to analyze the problem of the relationship between chemistry and physics, by focusing on the widely discussed case of the atomic orbitals. We will begin by remembering the difference between the physical and the chemical interpretation of the concept of orbital. Then, we will refer to the claim made in 1999 that atomic orbitals have been directly imaged for the first time. On this basis, we will analyze the problem from a new approach, (...) by comparing the concept of orbital used in physics with the concept of orbital used in chemistry. Such an analysis will allow us to argue for an ontological pluralism that admits the coexistence of different ontologies without priorities or metaphysical privileges. From this philosophical framework, the concepts of chemical orbital and physical orbital correspond to two different ontologies. As a consequence, chemical orbitals are real entities belonging to the ontology of molecular chemistry, and can be observed like any other entity not belonging to the quantum mechanical ontology. DOI:10.5007/1808-1711.2010v14n3p309. (shrink)

The analysis of the concept of orbital allows us to argue that—in opposition to a recent position in philosophy of science—it is impossible to defend the autonomy of the chemical reality in regard to physical reality, appealing to the idea that there is a conceptual rupture among a chemical interpretation and a quantuminterpretation of the concept. This is the case because there are not two different interpretations of the concept of orbital. On the contrary, the concept involved in structural chemistry (...) and in quantum chemistry comes from quantum mechanics.El análisis del concepto de orbital permite argumentar—en oposición a una propuesta reciente en filosofía de la química—que no es posible defender la autonomía ontológica de la realidad química respecto de la física, sobre la base de una ruptura conceptual entre una interpretación química del concepto y otra propia de la mecánica cuántica. Esto es así porque no existen tales interpretaciones distintas del concepto de orbital, sino que, por el contrario, este concepto en química cuántica y en química estructural proviene de la mecánica cuántica. (shrink)