This simulation study is a fuzzy model-based neural network control method. The basic idea is to consider the application of a special type of neural networks based on radial basis function, which belongs to a class of associative memory neural networks. The novelty of this approach is the use of an RBF neural network controller in a model reference adaptive control architecture, based on a one-step-ahead Takagi–Sugeno fuzzy model. The objective is to control the concentration in a continuous stirred-tank reactor (...) highly non-linear system and to assure its stability by limiting the temperature rise generated from the irreversible exothermic reaction. This contribution will help to reduce environmental impact of chemical waste. (shrink)

By comparing chemistry to art, chemists have recently made claims to the aesthetic value, even beauty, of some of their products. This paper takes these claims seriously and turns them into a systematic investigation of the aesthetics of chemical products. I distinguish three types of chemical products - materials, molecules, and molecular models - and use a wide variety of aesthetic theories suitable for an investigation of the corresponding sorts of objects. These include aesthetics of materials, idealistic (...) aesthetics from Plato to Kant and Schopenhauer, psychological approaches of Ernst Gombrich and Rudolf Arnheim, and semiotic aesthetics of Nelson Goodman and Umberto Eco. Although the investigation does not support recent claims, I point out where aesthetics does and can play an import role in chemistry. Particularly, Eco's approach helps us understand that and how aesthetic experience can be a driving force in chemical research. (shrink)

A general equation is derived describing the concentration of all possible complexes of a central molecule with a set of ligands bound to the central molecule. This deduction allows the reaction rate constants for the binding of a given molecule to the central molecule to depend on the species of molecules already bound and the location of the molecules already bound. The model thus allows for structural alteration of the central molecule by binding. Functions describing the concentration dependence of any (...) effect whatever depending on the distribution of complexes are deduced. Possible applications and methods of application are indicated.II est dérivé une équation qui décrit la concentration des toutes les complexes d'une molécule centrale avec une collection de ligands connectés à la molécule centrale. La déduction montre comme les coefficients de la rapidité de reaction entre la molécule centrale et les molécules de la collection dépend de l'espèce et de la location des molécules déjà connectées.La modèle dérivée de l'équation montre les changements structurelles par la connection. Les functions qui décrivent la dependence de chaque effet à la concentration, sont dérivés. Ces effects dépendent aussi à la distribution des complexes. Des applications et des méthodes sont indiqués.Eine allgemeine Vergleichung hat man bekommen welche die Konzentration aller möglichen Komplexen eines zentralen Moleküles mit einer Reihe von „Ligands” verbunden mit dem zentralen Molekül beschreibt. Diese Folgerung gestattet dass die Reaktiongeschwindigkeit Konstanten für die Bindung eines gegebenen Moleküles mit dem zentralen Molekül abhÄngt von den Arten schon gegebenen Molekülen und die Ortsbestimmung der schon gebundenen Molekülen. Das Model zeigt die strukturelle Änderungen des zentralen Moleküls durch Bindung. Funktionen, die die Konzentrationband jedes Effektes beschreiben dass abhÄngt von der Distribution der Komplexen, sind abgeleitet.Mögliche Anwendungen und Methoden von Anwendung sind dargelegt. (shrink)

Long-standing neglect of the chemical senses in the philosophy of perception is due, mostly, to their being regarded as ‘lower’ senses. Smell, taste, and chemically irritated touch are thought to produce mere bodily sensations. However, empirically informed theories of perception can show how these senses lead to perception of objective properties, and why they cannot be treated as special cases of perception modelled on vision. The senses of taste, touch, and smell also combine to create unified perceptions of flavour. (...) The nature of these multimodal experiences and the character of our awareness of them puts pressure on the traditional idea that each episode of perception goes one or other of the five senses. Thus, the chemical senses, far from being peripheral to the concerns of the philosophy of perception, may hold important clues to the multisensory nature of perception in general. (shrink)

Initially, models of chemical systems displaying oscillatory behavior were judged successful if they could show how such behavior was even possible. Recently, however, reaction mechanisms for chemical oscillators have been subjected to more stringent experimental tests. I examine strategies for model testing that flow from theoretical considerations, in particular, the types of feedback relations between chemical species required to produce oscillatory behavior in mechanistic models. These theoretical considerations allow chemists to work around important practical considerations (...) such as an inability to measure certain species in the experimental system. These sorts of testing strategies illuminate chemists' desiderata for a "good model.". (shrink)

The regulation of chemicals is undergoing drastic changes with the use of computational models to predict environmental toxicity. This particular issue has not attracted much attention, despite its major impacts on the regulation of chemicals. This raises the problem of causality at the crossroads between data and regulatory sciences, particularly in the case models known as quantitative structure–activity relationship models. This paper shows that models establish correlations and not scientific facts, and it engages anew the way (...) regulators deal with uncertainties. It does so by exploring the tension and problems raised by the possibility of causal explanation afforded by quantitative structure–activity relationship models. It argues that the specificity of predictive modelling promotes rethinking of the regulation of chemicals. (shrink)

From the perspective of successive events, chemical reactions are expressed or thought about, in terms of the cause-effect category. In this work, I will firstly discuss some aspects of causation and interaction in chemistry, argue for the interaction, and propose an alternative or complementary representation scheme called “interaction diagram”, that allows representing chemical reactions through a geometric diagram. The understanding of this diagram facilitates the analysis of reactions in terms of the interaction, or reciprocal action, among the participating (...) entities. Secondly, I will describe the model and provide examples and finally, I will discuss the scope and limitations of the current development status of the model. (shrink)

Roald Hoffmann and other theorists claim that we ought to use highly idealized chemical models (“qualitative models”) in order to increase our understanding of chemical phenomena, even though other models are available which make more highly accurate predictions. I assess this norm by examining one of the tradeoffs faced by model builders and model users—the tradeoff between precision and generality. After arguing that this tradeoff obtains in many cases, I discuss how the existence of this (...) tradeoff can help us defend Hoffmann's norm for modelling. (shrink)

Models as Make-Believe offers a new approach to scientific modelling by looking to an unlikely source of inspiration: the dolls and toy trucks of children's games of make-believe.

This open access book is a systematic update of the philosophical and scientific foundations of the biopsychosocial model of health, disease and healthcare. First proposed by George Engel 40 years ago, the Biopsychosocial Model is much cited in healthcare settings worldwide, but has been increasingly criticised for being vague, lacking in content, and in need of reworking in the light of recent developments. The book confronts the rapid changes to psychological science, neuroscience, healthcare, and philosophy that have occurred since the (...) model was first proposed and addresses key issues such as the model’s scientific basis, clinical utility, and philosophical coherence. The authors conceptualise biology and the psychosocial as in the same ontological space, interlinked by systems of communication-based regulatory control which constitute a new kind of causation. These are distinguished from physical and chemical laws, most clearly because they can break down, thus providing the basis for difference between health and disease. This work offers an urgent update to the model’s scientific and philosophical foundations, providing a new and coherent account of causal interactions between the biological, the psychological and social. (shrink)

Modern science is, to a large extent, a model-building activity. But how are models contructed? How are they related to theories and data? How do they explain complex scientific phenomena, and which role do computer simulations play here? These questions have kept philosophers of science busy for many years, and much work has been done to identify modeling as the central activity of theoretical science. At the same time, these questions have been addressed by methodologically-minded scientists, albeit from a (...) different point of view. While philosophers typically have an eye on general aspects of scientific modeling, scientists typically take their own science as the starting point and are often more concerned with specific methodological problems. There is, however, also much common ground in middle, where philosophers and scientists can engage in a productive dialogue, as the present volume demonstrates. To do so, the editors of this volume have invited eight leading scientists from cosmology, climate science, social science, chemical engeneering and neuroscience to reflect upon their modeling work, and eight philosophers of science to provide a commentary. (shrink)

This paper surveys some ways in which the chemical realm can be described and outlined in terms of the concept of supervenience. The particular contours of general chemical theory provide a ready basis for interpretation of determination, covariance, and nonreduction—the characteristic metaphysical facets of the supervenience relation—in mutual terms. Building on this, the extent to which chemically characterized properties and entities can be described in terms of a supervenience-scaffolded structure represents a particularly vivid application that philosophers in general (...) interested in supervenience would do well to attend to. In addition, the model of chemical supervenience given here can be used as a rubric on which to decide on issues already raised by philosophers of chemistry. (shrink)

Travelling waves crossing the nervous networks at mesoscopic/macroscopic scales have been correlated with different brain functions, from long-term memory to visual stimuli. Here we investigate a feasible relationship between wave generation/propagation in recurrent nervous networks and a physical/chemical model, namely the Belousov–Zhabotinsky reaction. Since BZ’s nonlinear, chaotic chemical process generates concentric/intersecting waves that closely resemble the diffusive nonlinear/chaotic oscillatory patterns crossing the nervous tissue, we aimed to investigate whether wave propagation of brain oscillations could be described in terms (...) of BZ features. We compared experimentally detected oscillations during the spontaneous activity of the brain with BZ-like concentric waves simulated by a recently introduced artificial network. The observed overlap and agreement between simulated and measured oscillatory patterns suggests that changes in cortical areas’ neural activity might be described in terms of a recognizable diffusion pattern. We describe biological plausibility, benefits and limits of our approach and discuss the relationship among BZ-like networks, Pandemonium-like architectures and the spontaneous activity of the brain. ER -. (shrink)

If chemistry is to be taught successfully, teachers must have a good subject matter knowledge (SK) of the ideas with which they are dealing, the nature of this falling within the orbit of philosophy of chemistry. They must also have a good pedagogic content knowledge (PCK), the ability to communicate SK to students, the nature of this falling within the philosophy and psychology of chemical education. Taking the case of models and modelling, important themes in the philosophy of (...) chemistry, an interview-based study was conducted into the SK and PCK of a sample of teachers in Brazil. This paper focuses on the results of the university chemistry teacher sub-sample in that enquiry, analyses their SK and PCK, and speculates on the implications of this for the education of school teachers. Finally, it suggests approaches to the professional development of university chemistry teachers that place an emphasis on the philosophy of chemistry. (shrink)

This article provides a theoretical policy-making model of chemical sunset that gradually substitutes green alternatives for persistent toxic substances within a finite timeframe. The technological inflexibility of these substances is a tough obstacle to a chemical sunset, because a chemical sunset seeks to ultimately stop, within a short period of time, the risky businesses of these substances that are highly entrenched into our society. In wrestling with this obstacle, the intelligent precautionary “polluter pays” principle integrates three policy (...) tools: a “precautionary `polluter pays' principle,” “intelligent trial and error,” and democratic “regulatory negotiation.” It is designed to promote technological pluralism and strong democracy, as well as to create either trust or mutual adjustment among relevant groups. (shrink)

In recent years the Chemical Revolution has become a renewed focus of interest among historians of science. This interest isshaped by interpretive strategies associated with the emergence anddevelopment of the discipline of the history of science. The disciplineoccupies a contested intellectual terrain formed in part by thedevelopment and cultural entanglements of science itself. Threestages in this development are analyzed in this paper. Theinterpretive strategies that characterized each stage are elucidatedand traced to the disciplinary interests that gave rise to them. (...) Whilepositivists and whigs appropriated the history of science to thejustificatory and celebratory needs of science itself, postpositivistslinked it to philosophical models of rationality, and sociologists ofknowledge sought its sociological reconstruction. Since none of thesestrategies do justice to the complexity of historical events, a modelof the Chemical Revolution is outlined which upholds the autonomyand specificity of history and the methods used to study it. (shrink)

Models underlying the use of similarity considerations, dimensionless numbers, and dimensional analysis in chemical engineering are discussed. Special attention is given to the many levels at which models and ceteris paribus conditions play a role and to the modeling of initial and boundary conditions. It is shown that both the laws or dimensionless number correlations and the systems to which they apply are models. More generally, no matter which model or description one picks out, what is (...) being modeled is itself a model of something else. Instead of saying that the artifact S models the given B, it is therefore better to say that S and B jointly make up B and S. (shrink)

The recent rapid development of information technology, such as sensing technology, communications technology, and database, allows us to use simulation experiments for analyzing serious accidents caused by hazardous chemicals. Due to the toxicity and diffusion of hazardous chemicals, these accidents often lead to not only severe consequences and economic losses, but also traffic jams at the same time. Emergency evacuation after hazardous chemical accidents is an effective means to reduce the loss of life and property and to smoothly resume (...) the transport network as soon as possible. This paper considers the dynamic changes of the hazardous chemicals’ concentration after their leakage and simulates the diffusion process. Based on the characteristics of emergency evacuation of hazardous chemical accidents, we build a mixed-integer programming model and design a heuristic algorithm using network optimization and diffusion simulation. We then verify the validity and feasibility of the algorithm using Jinan, China, as a computational example. In the end, we compare the results from different scenarios to explore the key factors affecting the effectiveness of the evacuation process. (shrink)

Two different models for chemical bond were developed almost simultaneously after the Schrödinger formulation of quantum theory. These are known as the valence bond (VB) and molecular orbital (MO) theories. Initially chemists preferred the VB theory and ignored the MO theory. Now the VB theory is almost dropped out of currency. The context of discovery and Linus Pauling’s overpowering influence gave the VB theory its initial advantage. The current universal acceptance of the MO theory is due to its (...) ability to provide direct interpretation of many different types of experiments now being pursued. In current research both localized bonds and delocalized charge distributions play important roles and the MO theory has been successful in giving a good account of both. (shrink)

In learning chemistry at the entry level, many learners labor under misconceptions about the subject matter that are so fundamental that they are typically never addressed. A fundamental misconception in chemistry appears to arise from an adding of existing phenomenal concepts to newly-acquired chemical concepts, so that beginning learners think of chemical entities as themselves having the very same ‘macro’ properties that we observe through the senses. Those who teach or practice chemistry never acquire these misconceptions because they (...) were able to naturally pick up the nature of the subject to begin with. But as a result, they remain unaware of the foundational assumptions and understanding that they operate with and that many beginning learners persistently lack. Thus, a systematic picture of the workings of chemical theory as they relate to observable phenomena needs to be elucidated so that the attention of chemical educators is drawn to the fundamental understanding of the subject that they already possess and that beginning learners of chemistry lack, so that beginning learners can be given the opportunity to gain an understanding of how chemical explanations are in general related to observable phenomena. The ‘layered’ way in which chemical and physical entities are related to each other within chemical theory can also be clarified in this way. To afford this picture, the philosophical concepts of supervenience and emergence are explained and applied to chemistry, as philosophers of chemistry have already done. The result provides a model for teaching chemistry that, if consistently applied, has the potential to greatly enhance fundamental understanding of the subject matter. (shrink)

The concepts of atoms and bonds in molecules which appeared in chemistry during the nineteenth century are unavoidable to explain the structure and the reactivity of the matter at a chemical level of understanding. Although they can be criticized from a strict reductionist point of view, because neither atoms nor bonds are observable in the sense of quantum mechanics, the topological and statistical interpretative approaches of quantum chemistry (quantum theory of atoms in molecules, electron localization function and maximum probability (...) domain) provide consistent definitions which accommodate chemistry and quantum mechanics. (shrink)

Kinetic models using enzyme kinetics are developed for the three ways that Louie proved that Rosen’s minimal (M-R)-System can be closed to efficient cause; i.e., how the “replication” component can itself be entailed from within the system. The kinetic models are developed using the techniques of network thermodynamics. As a demonstration, each model is simulated using a SPICE circuit simulator using arbitrarily chosen rate constants. The models are built from SPICE sub-circuits representing the key terms in the (...) chemical rate equations. The models include the addition of an ad hoc semi-permeable membrane so the system can achieve steady state fluxes and also to illustrate the need for all the efficient cause agents to be continually replaced. Comments are made about exactly what is being simulated. (shrink)

I apply James Woodward’s interventionist theory of causation to organic chemistry, modelling three different ways that chemists are able to manipulate the reaction conditions in order to control the outcome of a reaction. These consist in manipulations to the reaction kinetics, thermodynamics, and whether the kinetics or thermodynamics predominates. It is possible to construct interventionist causal models of all of these kinds of manipulation, and therefore to account for them using Woodward’s theory. However, I show that there is an (...) alternate, more illuminating way of thinking about the third kind of reaction control, according to which chemists are thought of as manipulating which causal system is instantiated. I show that our ability to manipulate which system is instantiated is an important part of our ability to control the world, as is therefore especially relevant to interventionism. Thus, considering examples from organic chemistry leads to the identification of an important extension to Woodward’s theory. Finally, this investigation into reaction control in organic chemistry also has a more general implication: it suggests that interventionism results in a version of pragmatism about causation. (shrink)

The ArgumentThe relation between alchemy and early chemistry is still open to debate. How did what is now often dismissed as a pseudo-science contribute to the emerging science of chemistry, a subject that by the late eighteenth century, was often held up as a model for other sciences? Alchemy may have bequeathed to chemistry some processes and apparatus; more fundamental, however, was a transformation in mentality. It was in the seventeenth century that much of this transformation took place.A study that (...) was deeply anthropomorphic, making constant use of allegories and symbolism, and with a language rejoicing in mystery and concealment, gradually became depersonalized, much more objective, and more open. Poetic descriptions, a moral dimension, and a hierarchical view of matter all disappeared. Practical considerations required a concern for greater purity of materials, necessary for the successful replication of experiments. A study of the series of seventeenth-century French textbooks of chemistry from Beguin to Lemery reveals a growing desire for practical results and plain speaking. Robert Boyle was particularly influential in urging the necessity of plain language. The creation of a suitable language to denote and differentiate among different chemical species was a crucial step in the development of early chemistry, thus preparing the way for the systematic names introduced in the following century and the full organization of the science on rational lines. (shrink)

This collection of essays deals with three clusters of problems in the philo sophy of science: scientific method, conceptual models, and ontological underpinnings. The disjointedness of topics is more apparent than real, since the whole book is concerned with the scientific knowledge of fact. Now, the aim of factual knowledge is the conceptual grasping of being, and this understanding is provided by theories of whatever there may be. If the theories are testable and specific, such as a theory of (...) a particular chemical reaction, then they are often called 'theoretical models' and clas sed as scientific. If the theories are extremely general, like a theory of syn thesis and dissociation without any reference to a particular kind of stuff, then they may be called 'metaphysical' - as well as 'scientific' if they are consonant with science. Between these two extremes there is a whole gamut of kinds of factual theories. Thus the entire spectrum should be dominated by the scientific method, quite irrespective of the subject matter. This is the leitmotiv of the present book. The introductory chapter, on method in the philosophy of science, tackles the question 'Why don't scientists listen to their philosophers?'. (shrink)

In contrast to the conventional homogeneous kinetics, there is no conception of a simple reaction in the solid-state reaction kinetics. The geometric-probabilistic phenomenology currently in use is not adequate for describing the interplay between the chemical mechanism and the observed kinetic behaviour. An attempt is made to formulate a conception of simple reaction in the solid state as a basis for constructing kinetic models of involved reactions.

Molecular models are typical topics of chemical research depending on the technical standards of observation, computation, and representation. Mathematically, molecular structures have been represented by means of graph theory, topology, differential equations, and numerical procedures. With the increasing capabilities of computer networks, computational models and computer-assisted visualization become an essential part of chemical research. Object-oriented programming languages create a virtual reality of chemical structures opening new avenues of exploration and collaboration in chemistry. From an epistemic (...) point of view, virtual reality is a new computer-assisted tool of human imagination and recognition. (shrink)

During the second half of the nineteenth century, electronegativity has been one of the most relevant chemical concepts to explain the relationships between chemical substances and their possible reactions. Specifically, EN is a property of the substances that allows them to attract external electrons in bonding situations. The problem arises because EN cannot be measured directly. Indeed, the only way to measure it is through different properties that do can be directly measured, for instance enthalpy, ionization energies or (...) electron affinities. What is particularly troubling about this case in quantum chemistry is that the different models used to describe and quantify EN are incompatible but, in a certain sense, equivalent because the same EN scale results in all of them. By analyzing Linus Pauling’s and Robert Mulliken’s models of EN, it will be argued that, if we remain cling to a traditional representative conception of models, we cannot understand the meaning of the information provided by those models. Indeed, if we do not want to adopt an instrumentalist point of view concerning chemical knowledge, we should reconsider by virtue of what a model represents the system, or, in other words, which the factors that determine the representative power of a model are. I will propose a new perspective that incorporates the role of experimental techniques in the very notion of representation; this perspective allows us to understand how supposedly incompatible models of the same target system can be both simultaneously representative. (shrink)

The dissemination of models across disciplinary lines has become a phenomenon of interest to philosophers of science. To account for this phenomenon, philosophers have invented two units of analysis. The first identifies to the thing that transfers, model templates. The second identifies the thing to which transferable templates apply, landing zones. There exists a dynamic between the thing that is transferred and the thing to which transferrable templates apply. The use of a transferable template in a new domain requires (...) reconception of domain-specific phenomena. This paper examines two cases of model transfer, the use of the ideal gas law in biology by R.A. Fisher and the use of the virial theorem in chemistry by Richard Bader. These two stories of model transfer in biology and chemistry indicate a dimension to conceptual progress related to this dynamic. Using discourse on model transfer affords philosophers a novel approach for depicting the invention of, for instance, chemical concepts and resulting disputes. (shrink)

Mental model construction is supposed to be a useful cognitive devise for learning. Beyond human capacity of constructing mental models, scientists construct complex explanations about phenomena, named scientific or theoretical models. In this work we revisit three vissions: the first one concern about the polisemic term “model”. Our proposal is to discriminate between “mental models” and “explicit models”, being the former those “imaginistic” ideas constructed in scientists’—o teachers—minds, and the latter those teaching devices expressed in different (...) languages that tend to communicate any “scientific model”. From this point of view, the class is considered a place where teachers’ mental models should be learned by novice students by decoding their teaching devices which are expressed in different languages. Other proposal of this work claims to distinguish the term “representation” with respect to its artistical or instrumental origin, highlighting that they are types of teaching devices and that artistical representations are always analogies. Finally, data about the construction of freshmen’s wrong mental models related to the use of the analogy between the chemical combustion and the global process of cellular respiration from glucose is presented to reinforce previous epistemological reflections. (shrink)

This article explores the use of model organisms in studying the cognitive phenomenon of decision-making. Drawing on the framework of biological control to develop a skeletal conception of decision-making, we show that two core features of decision-making mechanisms can be identified by studying model organisms, such as E. coli, jellyfish, C. elegans, lamprey, and so on. First, decision mechanisms are distributed and heterarchically structured. Second, they depend heavily on chemical information processing, such as that involving neuromodulators. We end by (...) discussing the implications for studying distinctively human decision-making. (shrink)

We discuss potential biorisks from large language models (LLMs). AI assistants based on LLMs such as ChatGPT have been shown to significantly reduce barriers to entry for actors wishing to synthesize dangerous, potentially novel pathogens and chemical weapons. The harms from deploying such bioagents could be further magnified by AI-assisted misinformation. We endorse several policy responses to these dangers, including prerelease evaluations of biomedical AIs by subject-matter experts, enhanced surveillance and lab screening procedures, restrictions on AI training data, (...) and access controls on biomedical AI. We conclude with a suggestion about future research directions in bioethics. (shrink)

The dissemination of models across disciplinary lines has become a phenomenon of interest to philosophers of science. To account for this phenomenon, philosophers have invented two units of analysis. The first identifies to the thing that transfers, model templates. The second identifies the thing to which transferable templates apply, landing zones. There exists a dynamic between the thing that is transferred and the thing to which transferrable templates apply. The use of a transferable template in a new domain requires (...) reconception of domain-specific phenomena. This paper examines two cases of model transfer, the use of the ideal gas law in biology by R.A. Fisher and the use of the virial theorem in chemistry by Richard Bader. These two stories of model transfer in biology and chemistry indicate a dimension to conceptual progress related to this dynamic. Using discourse on model transfer affords philosophers a novel approach for depicting the invention of, for instance, chemical concepts and resulting disputes. (shrink)

The dissemination of models across disciplinary lines has become a phenomenon of interest to philosophers of science. To account for this phenomenon, philosophers have invented two units of analysis. The first identifies to the thing that transfers, model templates. The second identifies the thing to which transferable templates apply, landing zones. There exists a dynamic between the thing that is transferred and the thing to which transferrable templates apply. The use of a transferable template in a new domain requires (...) reconception of domain-specific phenomena. This paper examines two cases of model transfer, the use of the ideal gas law in biology by R.A. Fisher and the use of the virial theorem in chemistry by Richard Bader. These two stories of model transfer in biology and chemistry indicate a dimension to conceptual progress related to this dynamic. Using discourse on model transfer affords philosophers a novel approach for depicting the invention of, for instance, chemical concepts and resulting disputes. (shrink)

This paper aims to develop an account of the pursuitworthiness of models based on a view of models as epistemic tools. This paper is motivated by the historical question of why, in the 1960s, when many scientists hardly found QSAR models attractive, some pharmaceutical scientists pursued Quantitative Structure–Activity Relationship (QSAR) models despite the lack of potential for theoretical development or empirical success. This paper addresses this question by focusing on how models perform their heuristic functions (...) as epistemic tools rather than as potential theories. I argue that models perform their heuristic function by “constructing” phenomena from data in the sense that they allow the model users who interact with the medium of the models to recognise the phenomena as such. The constructed phenomena assist model users in identifying which conditional hypotheses that are focused on low-level regularities concerning entities such as chemical compounds are more “testworthy,” a concept that links the costs associated with hypothesis testing with the fertility of the hypothesis. (shrink)

The covalent bond, a difficult concept to define precisely, plays a central role in chemical predictions, interventions, and explanations. I investigate the structural conception of the covalent bond, which says that bonding is a directional, submolecular region of electron density, located between individual atomic centers and responsible for holding the atoms together. Several approaches to constructing molecular models are considered in order to determine which features of the structural conception of bonding, if any, are robust across these (...) class='Hi'>models. Key components of the structural conception are absent in all but the simplest quantum mechanical models of molecular structure, seriously challenging the conception’s viability. †To contact the author, please write to: Department of Philosophy, University of Pennsylvania, 433 Cohen Hall, Philadelphia, PA 19104‐6304; e‐mail: [email protected]. (shrink)

This paper argues for the theoretical and practical validity of similarity as a useful epistemological tool in scientific knowledge generation, specifically in chemistry. Classical analyses of similarity in philosophy of science do not account for the concept’s practical significance in scientific activities. We recur to examples from chemistry to counter the claim of authors like Quine or Goodman to the effect that similarity must be excluded from scientific practices . In conclusion we argue that more recent conceptualizations of the notion (...) of similarity, particularly Giere’s one, are appropriate for a philosophical analysis that considers scientific practices on equal terms with scientific theory. (shrink)

In this paper it is performed a historical account of the theoretical roots that grounded the following four key basic ideas of chemical equilibrium: ‘incomplete reaction’, ‘reversibility’, ‘equilibrium constant’ and ‘molecular dynamics’. These notions developed in nineteenth-century as a consequence of the evolution of the concept of chemical affinity. The discussion begins with the presentation of the earliest affinity table [‘Table des rapports’] published in 1718 by Geoffroy. Afterwards, it is examined Bergman’s compilation. The theory supporting this arrangement (...) assumed that chemical displacement reactions were complete and could not be reversed. It is analysed how Berthollet’s model showed the inadequacy of this view. His new conceptual considerations established that the amount of the substances involved in a reaction was an essential factor determining its direction, which accounted for the early concepts of incomplete reaction and reversibility. Guldberg and Waage specified the role of mass in chemical equilibrium reactions as they considered the concentrations of the chemicals involved, formulating the first chemical equilibrium mathematical equation that approximates what is called nowadays chemical equilibrium constant. Finally, it is presented how Pfaundler was the first to consider the kinetic theory in the interpretation of the macroscopic properties of equilibrium reactions. (shrink)

Diagrams can serve as representational models in scientific research, yet important questions remain about how they do so. I address some of these questions with a historical case study, in which diagrams were modified extensively in order to elaborate an early hypothesis of protein synthesis. The diagrams’ modelling role relied mainly on two features: diagrams were modified according to syntactic rules, which temporarily replaced physico-chemical reasoning, and diagram-to-target inferences were based on semantic interpretations. I then explore the lessons (...) for the relative roles of syntax, semantics, external marks, and mental images, for justifying diagram-to-target inferences, and for the “artefactual approach” to scientific models. (shrink)

This thesis focuses on models of conceptual change in science and philosophy. In particular, I developed a new bootstrapping methodology for studying conceptual change, centered around the formalization of several popular models of conceptual change and the collective assessment of their improved formal versions via nine evaluative dimensions. Among the models of conceptual change treated in the thesis are Carnap’s explication, Lakatos’ concept-stretching, Toulmin’s conceptual populations, Waismann’s open texture, Mark Wilson’s patches and facades, Sneed’s structuralism, and Paul (...) Thagard’s conceptual revolutions. -/- In order to analyze and compare the conception of conceptual change provided by these different models, I rely on several historical reconstructions of episodes of scientific conceptual change. The historical episodes of scientific change that figure in this work include the emergence of the morphological concept of fish in biological taxonomies, the development of scientific conceptions of temperature, the Church-Turing thesis and related axiomatizations of effective calculability, the history of the concept of polyhedron in 17th and 18th century mathematics, Hamilton’s invention of the quaternions, the history of the pre-abstract group concepts in 18th and 19th century mathematics, the expansion of Newtonian mechanics to viscous fluids forces phenomena, and the chemical revolution. I will also present five different formal and informal improvements of four specific models of conceptual change. I will first present two different improvements of Carnapian explication, a formal and an informal one. My informal improvement of Carnapian explication will consist of a more fine-grained version of the procedure that adds an intermediate, third step to the two steps of Carnapian explication. I will show how this novel three-step version of explication is more suitable than its traditional two-step relative to handle complex cases of explications. My second, formal improvement of Carnapian explication will be a full explication of the concept of explication itself within the theory of conceptual spaces. By virtue of this formal improvement, the whole procedure of explication together with its application procedures and its pragmatic desiderata will be reconceptualized as a precise procedure involving topological and geometrical constraints inside the theory of conceptual spaces. My third improved model of conceptual change will consist of a formal explication of Darwinian models of conceptual change that will make vast use of Godfrey-Smith’s population-based Darwinism for targeting explicitly mathematical conceptual change. My fourth improvement will be dedicated instead to Wilson’s indeterminate model of conceptual change. I will show how Wilson’s very informal framework can be explicated within a modified version of the structuralist model-theoretic reconstructions of scientific theories. Finally, the fifth improved model of conceptual change will be a belief-revision-like logical framework that reconstructs Thagard’s model of conceptual revolution as specific revision and contraction operations that work on conceptual structures. -/- At the end of this work, a general conception of conceptual change in science and philosophy emerges, thanks to the combined action of the three layers of my methodology. This conception takes conceptual change to be a multi-faceted phenomenon centered around the dynamics of groups of concepts. According to this conception, concepts are best reconstructed as plastic and inter-subjective entities equipped with a non-trivial internal structure and subject to a certain degree of localized holism. Furthermore, conceptual dynamics can be judged from a weakly normative perspective, bound to be dependent on shared values and goals. Conceptual change is then best understood, according to this conception, as a ubiquitous phenomenon underlying all of our intellectual activities, from science to ordinary linguistic practices. As such, conceptual change does not pose any particular problem to value-laden notions of scientific progress, objectivity, and realism. At the same time, this conception prompts all our concept-driven intellectual activities, including philosophical and metaphilosophical reflections, to take into serious consideration the phenomenon of conceptual change. An important consequence of this conception, and of the analysis that generated it, is in fact that an adequate understanding of the dynamics of philosophical concepts is a prerequisite for analytic philosophy to develop a realistic and non-idealized depiction of itself and its activities. (shrink)