Idealization and the structure of biological theories (original) (raw)
Related papers
In this paper we present a new framework of idealization in biology. We characterize idealizations as a network of counterfactual and hypothetical conditionals that can exhibit different “degrees of contingency”. We use this idea to say that, in departing more or less from the actual world, idealizations can serve numerous epistemic, methodological or heuristic purposes within scientific research. We defend that, in part, this structure explains why idealizations, despite being deformations of reality, are so successful in scientific practice. For illustrative purposes, we provide an example from population genetics, the Wright-Fisher Model.
The challenges and scope of theoretical biology
Journal of Theoretical Biology, 2011
Scientific theories seek to provide simple explanations for significant empirical regularities based on fundamental physical and mechanistic constraints. Biological theories have rarely reached a level of generality and predictive power comparable to physical theories. This discrepancy is explained through a combination of frozen accidents, environmental heterogeneity, and widespread non-linearities observed in adaptive processes. At the same time, model building has proven to be very successful when it comes to explaining and predicting the behavior of particular biological systems. In this respect biology resembles alternative model-rich frameworks, such as economics and engineering. In this paper we explore the prospects for general theories in biology, and suggest that these take inspiration not only from physics, but also from the information sciences. Future theoretical biology is likely to represent a hybrid of parsimonious reasoning and algorithmic or rule-based explanation. An open question is whether these new frameworks will remain transparent to human reason. In this context, we discuss the role of machine learning in the early stages of scientific discovery. We argue that evolutionary history is not only a source of uncertainty, but also provides the basis, through conserved traits, for very general explanations for biological regularities, and the prospect of unified theories of life.
Formalization and the Meaning of “Theory” in the Inexact Biological Sciences
Biological Theory, 2012
ABSTRACT Exact sciences are described as sciences whose theories are formalized. These are contrasted to inexact sciences, whose theories are not formalized. Formalization is described as a broader category than mathematization, involving any form/content distinction allowing forms, e.g., as represented in theoretical models, to be studied independently of the empirical content of a subject-matter domain. Exactness is a practice depending on the use of theories to control subject-matter domains and to align theoretical with empirical models and not merely a state of a science. Inexact biological sciences tolerate a degree of “mismatch” between theoretical and empirical models and concepts. Three illustrations from biological sciences are discussed in which formalization is achieved by various means: Mendelism, Weismannism, and Darwinism. Frege’s idea of a “conceptual notation” is used to further characterize the notion of a form/content distinction.
Models in philosophy of biology: a pragmatic approach
The term model in philosophy of biology points at a number of non-coincident concepts. Such a multiplicity - I argue - can hinder debates, especially those in which multiple, heterogeneous elements are eligible as models. I argue that the goal of defining shared and uniform criteria for the identification of models in biology seems not achievable, and thus suggest a pragmatic approach: I propose the choice of model concept to be shared, contextual and functional to the single discussion in philosophy of biology; I also recommend as much clarity as possible about the local intended meaning of the term model. The model notion was brought “in centre stage” in philosophy of biology in the 1980s by authors (mainly Lloyd, Beatty, and Thompson) within the “semantic view of theories”. The concept of a model, strictly understood as meta-mathematical, was seen on the one hand as an improvement - relative to the logical empiricist “received view” (e.g. Suppe 1977) - for specifying the axiomatic structure of theories, on the other hand as a particularly appropriate description of the mathematical core of evolutionary biology. i.e. population genetics (e.g. Lloyd 1988), especially through the “state spaces” approach (Van Fraassen 1980). The semantic view and the model concept were also presented as resources for characterizing biology rightfully as a science, meeting some of its peculiarities such as the lack of “universal laws”. In the years that followed, the concept of model remained central in philosophical accounts of biology, but while the semantic view stood as an inclusive “big tent” (Godfrey-Smith 2006) the model concept diversified, drifting away from the primal logic-mathematical formulation (e.g. Downes 1992). Very soon, for instance, the variety of degrees of abstractions of models and the contextual nature of their relationships with the world were acknowledged (Giere 1988). Besides mathematical models, philosophers of biology began to consider and define other kinds of scientific models, like e.g. experimental laboratory systems or simulations, coming up to include among models even museum specimens and collections (Griesemer 1990). Recent works (Morgan & Morrison 1999) pointed out the heterogeneity of scientific models, the absence of general rules for their building, and their partial autonomy from both “world” and theories. Despite such a multiplication, the concept of model often appears in philosophical debates with insufficient specification, or without an agreement fitting with the discussed phenomena. As an instance, I conducted an analysis of the recent debate on “fitness landscapes” (Wright 1932) in evolutionary biology (e.g. Provine 1986; Ruse 1992; Skipper 2004; Kirkpatrick & Rousset 2005; Pigliucci & Kaplan 2006, 2008; Reiss 2007; Calcott 2008; Wilkins & Godfrey-Smith 2009). The analysis shows how diverging conceptions of model can confuse the debate, or prevent it from reaching issues by bending it towards general clarifications about models. Cases like this are particularly complex in that they offer different elements as potential candidates to the role of model (mathematical equations, diagrams with multiple interpretations, verbal descriptions, and more) and also potentially alternative terms like “theory” and “metaphor”. At present it is difficult to require, for the model category, universal criteria - whether they concern peculiar building strategies, particular relationships with world or theory, constitutional requirements or whatever else. It seems more promising to adopt a pragmatic approach (e.g. Plutynski 2004) that considers the scientific context to establish, case by case, “what counts as a model and how”. From such an approach stems a precautional request of clarification, agreement, and functionality of the meaning of model in debates in philosophy of biology.
Scientific Understanding and the Explanatory Use of False Models
2015
In model-based sciences, like biology, models play an outstanding explanatory role. In recent times, some authors have shown how the notion of understanding could shed light on the analysis of explanation based on models. This notion has attracted growing attention in philosophy of science. Three important questions have been central in the debate: (1) What is scientific understanding?; (2) is understanding factive, i.e., does understanding presuppose or imply truth?; and (3) can understanding be objective? I will outline and assess the main answers to these questions and I will support my personal contribution to question number 2 and 3.
The predictive capacity of biological theories
There have been intense debates since the 1950’s about the possibility to use the theory of natural selection to derive predictions. Most of the discussions about the predictiveness of biology (the “predictiveness thesis”) involved arguments about the status of biological theories, the presence of laws in biology, and so on. But few comments have been made on the different kinds of predictions and on the specific status of predictions in biology. I focus on this issue, and maintain that it is not necessary to claim that biological and physical theories have identical status and realize predictions in the same way to support the predictiveness thesis.
THE IMPASSE OF ENCOMPASSING MODERN BIOLOGICAL THEORIES
Within scholarly disciplines the use of concepts is usually embedded in a theoretical view of reality. The latter hides the problem of what is given in an ontic sense or viewed as theoretical constructs. Particularly in respect of living entities there is a general tendency not to distinguish between the multi-faceted nature of living entities and the biotic function of such entities. Leading neo-Darwinian biologists do realize that since molecules are not alive it is mistaken to speak about "molecular biology." This fact motivated the physicist Erwin Schrödinger, to publish a work on the physical aspect of the cell. He explained the apparent mysterious ability of living entities to increase biotic order within themselves by showing that organisms feed on negative entropy. Von Bertalanffy generalized the second main law of thermodynamics to open systems in order to account for the dynamic "Fliessgleichgewicht" (flowing equilibrium) found in living entities. With reference to the nucleoplasmic index a few remarks are made in respect of the quantitative, spatial and kinematic properties of a cell. These remarks depend upon an insight into the modal universality of the various aspects of reality. It also opens the way to distinguish between modal (aspectual) laws and type laws -where the former hold for all classes of entities with the latter only for a limited class of entities. The big bang theory presupposes the first two laws of physics as well as the irreducibility of number, space, movement and energy-operation as modes of explanation. These laws render the attempt of Hawking to argue that the law of gravity would create the universe meaningless -illustrated by a brief analysis of the law of gravity. This raises the question if physical entities, such as atoms, molecules and macro-molecules, can account for the origin of living entities. Dobzhansky considers the origin of "life" and of "man" as two crises in the "flow of evolutionary events." Pierre Durand recently claims that the problem of the "origin of life" is solved by explaining it through the accidental formation of RNA (Ribonucleic Acid) strings. However, since living entities require proteins and nucleic acid (DNA), the assumption is that initially protein and DNA had to be present at once. The vicious circle is that without nucleic acids (DNA) the cell lacks the ability to construct proteins and without proteins the cell cannot function as a living unit. Invoking the idea of millions of years does not help, because the truly critical point is condensed into a unique, abrupt moment: before a specific moment the constellation was still non-living and the next moment it became alive. Von Bertalanffy ridicules the physicalist idea that molecules could be alive when he states that one DNA molecule, protein, enzyme or hormonal process is as good as another; each is determined by Vol. 74 | No. physical and chemical laws, none is better, healthier or more normal than the other. Producing specified information from purely physical or chemical precursors has never been shown to be possible. Gould refers to Dobzhansky who posed the key question of organic form and taxonomy: "why do organisms form discrete and clearly nonrandom 'clumps' in populating morphological space? Why does the domain of mammalian carnivores contain a large cluster of cats, another of dogs, a third of bears, leaving so much unoccupied morphological space between?" The central problem of evolution, according to Dobzhansky, is the origin of discontinuity among species. Emergent-evolutionism wants to have it both ways: continuity in descent and discontinuity in existence. Rensch and Wright revert to assigning "protopsychical" properties to matter. Wright argues that if mind is totally absent in the non-living universe its appearance will be inexplicable -the emergence of mind from no mind at all is sheer magic. Perhaps the most prominent neo-Darwinian biologist questioning the continuity postulate in biology (actually going back to Leibniz) is Stephen Gould who wrote that these stories begin from the same foundational fallacy and then proceed in an identically erroneous way. They start with the most dangerous of mental traps: a hidden assumption, depicted as selfevident, if recognized at all-namely, a basic definition of evolution as continuous flux. Surely, the impasse exposed in this article will continue to pose a serious challenge to future biological thought.
Theory is as Theory Does: Scientific Practice and Theory Structure in Biology
Biological Theory, 2012
Using the context of controversies surrounding evolutionary developmental biology (EvoDevo) and the possibility of an Extended Evolutionary Synthesis, I provide an account of theory structure as idealized theory presentations that are always incomplete (partial) and shaped by their conceptual content (material rather than formal organization). These two characteristics are salient because the goals that organize and regulate scientific practice, including the activity of using a theory, are heterogeneous. This means that the same theory can be structured differently, in part because theory presentations (as idealizations) intentionally depart from different features known to be present in a theory. Since there are diverse and potentially Love, A.C. (in press) "Theory is as theory does: scientific practice and theory structure in biology", Biological Theory.