"Models, Laws, and Theories in Population Dynamics"

DÍAZ, MARTÍN; LORENZANO, PABLO

Encuentro; 2017 Meeting. International Society for the History, Philosophy and Social Studies of Biology (ISHPSSB) & Associação Brasileira de Filosofia e História da Biologia (ABFHiB); 2017

International Society for the History, Philosophy and Social Studies of Biology (ISHPSSB) & Associação Brasileira de Filosofia e História da Biologia (ABFHiB)

One of the most discussed branches of ecology is thatof population ecology, in particular population dynamics. Due to the fact thatit was the first branch of ecology which made an intensive use of numericalmathematics, it was thought that that area was appropriate for achievingquantitative laws or theories (Turchin, 2001). After almost one hundred years ofexistence, different equations, or models, representing the dynamical behaviorof populations along time (logistic, exponential, predator-prey, etc.) wereestablished. Out of this fact, it has been discussed the issue of the existenceof laws in ecology. While some authors claim that ecology doesn?t have empiricallaws, because of the use of mathematics transformed population ecology into anabstract science, whose models don?t have any connection to reality and,therefore, do lack of empirical value (Cooper, 2003), others sustain thatpopulation ecology does haveempirical laws similar to the laws of physics (Berryman, 2003; Colyvan, 2003,Turchin, 2001). Among the latter are also ecologists, who argue that theexponential law of population growth, derived from Malthus? equation, is the generallaw of population dynamics (Berryman, 2003; Ginzburg, 1986; Turchin, 2001).The aim of this presentation is to analyze thestatus of the exponential law of population growth, and other well-knownequations or models of population dynamics. The analysis will be carried outwith the tools of one version of the semantic view of theories, namely, that ofmetatheoretical, or Sneedian, structuralism (Balzer, Moulines & Sneed1987), especially those of model, fundamental law, and theory-net, having as abackground a rational reconstruction of population dynamics ? sketched in this communication?  made within the framework of such ametatheory. Our analysis will show that: 1) there is a reasonable sense inwhich we can speak of a fundamental law of population dynamics, different fromthe exponential law of population growth, which can be seen as a special law ofpopulation dynamics; 2) the distinct heterogeneous models of populationdynamics can be accommodated under one theory-net, namely, the theory-net ofpopulation dynamics; and 3) the last situation is what confers to populationdynamics its great unifying power, similar to that of theories belonging toother scientific disciplines, such as Classical Particle Mechanics.