Scientific Models in Philosophy of Science

1 Scientific Models

I    in this book to present views on models across philosophy of science. This is done with the view to highlight philosophical issues that arise when thinking about scientific modeling. To orient the reader, I begin with an outline of my position of what a scientific model is in section 1.1. In section 1.2, I present results from interviews with scientists from various disciplines to illustrate what scientists think scientific models are. In section 1.3, I briefly discuss methodological difficulties of a philosophical study of models, and in section 1.4, I give an outline of the whole book. 1.1 What I Take Scientific Models To Be I consider the following as the core idea of what constitutes a scientific model: A model is an interpretative description of a phenomenon that facilitates access to that phenomenon. (“Phenomenon” refers to “things happening”—more on this in chapter 7.) This access can be perceptual as well as intellectual. If access is not perceptual, it is often facilitated by visualization, although this need not be the case. Interpretative descriptions may rely, for instance, on idealizations or simpli fications or on analogies to interpretative descriptions of other 1 S C IENTIFIC M OD E L S M EC H ANIC AL MOD EL S AN AL OGY THEORIE S PARAD IGM S AND M ETAPH ORS THE S EM ANTIC VIE W AND THE S TUDY OF SC IEN TIFIC PR ACTIC E PH EN OM EN A , DATA , AND DATA MODE L S REPRE SE NTATION CONCL USION 1 2 3 4 5 6 7 8 9 Bailer CH1:Layout 1 7/5/09 2:02 PM Page 1 phenomena. Facilitating access usually involves focusing on specific aspects of a phenomenon, sometimes deliberately disregarding others. As a result, models tend to be partial descriptions only. Models can range from being objects, such as a toy airplane, to being theoretical, abstract entities, such as the Standard Model of the structure of matter and its fundamental particles. As regards the former, scale models facilitate looking at something by enlarging it (for example, a plastic model of a snowflake) or shrinking it (for example, a globe as a model of Earth). This can involve making explicit features that are not directly observable (for example, the structure of DNA or chemical elements contained in a star). The majority of scientific models are, however, a far cry from consisting of anything material, like the rods and balls of molecular models sometimes used for teaching; they are highly theoretical. They often rely on abstract ideas and concepts, frequently employing a mathematical formalism (as in the big bang model, for example), but always with the intention to provide access to aspects of a phenomenon that are considered to be essential. Bohr’s model of the atom informs us about the configurations of the electrons and the nucleus in an atom, and the forces acting between them; or modeling the heart as a pump gives us a clue about how the heart functions. The means by which scientific models are expressed range from the concrete to the abstract: sketches, diagrams, ordinary text, graphs, and mathematical equations, to name just a few. All these forms of expression serve the purpose of providing intellectual access to the relevant ideas that the model describes. Providing access means giving information and interpreting it and expressing it efficiently to those who share in a specific intellectual pursuit. In this sense, scientific models are about empirical phenomena, whether these are how metals bend and break or how man has evolved.₁ Models come in a variety of forms—that is, they employ different external representational tools that need not exclude each other. One form is that of ordinary language sentences written on a piece of paper. Take the following example of the hydrostatic equilibrium model of main sequence stars. Due to this equilibrium, such stars do not shrink or expand. According to the model, the gravitational pressure exerted 2 Scientific Models Bailer CH1:Layout 1 7/5/09 2:02 PM Page 2 by the very large interior mass of the star would pull the exterior layers of the star inward and would cause the star to collapse if this pressure was not resisted by the gas pressure (and/or radiation pressure) of the stellar material inside...