Causality, Teleology, System: Laws in the Special Sciences from Frank to Nagel

The special sciences, so the usual characterization goes, do not possess laws of the same kind as physics and are based on concepts that cannot be reduced to physical ones. This makes, so the argument continues, the disunity of science a plausible working hypothesis. In recent years, this argument has been properly countered by invoking Otto Neurath’s starkly different conception of unity of science that made possible to integrate the special sciences into the Encyclopedia of Unified Sciences as long as their representatives remained committed to an empiricist outlook and followed a physicalist language in the wider sense, mainly by avoiding metaphysical terms and a metaphysical reading of scientific formalism. Complementing recent works on the special sciences in the Encyclopedia (Hofer 2013) and the criticism against metaphysics by the emerging philosophy of science (Uebel 2011), my paper looks at the first aspect and investigates the influence of the concept of causality on the debates about the special sciences. Emphasis will be placed on the discussions in the 1920s and 1930s, mainly on Philipp Frank’s book The Law of Causality and Its Limits, and Ernest Nagel’s post-war attempts to develop a system-property account of teleology and functional explanation. The basic idea is this: For an empiricist who rejects a metaphysical disunity of science that introduces entelechies or wholenesses (Ganzheiten) distinct from physical science – there exists a trade-off between the concept of causality and the concepts of system or teleology used in describing characteristic – though not exclusive – features of biology and psychology. While a liberal notion of causality like Mach’s – who avoided the word altogether – allows one to integrate most allegedly teleological features into a unified concept of functional dependency, more narrowly conceived notions of causality require the additional specification of characteristic features of teleological behavior or the existence of a system state. In Mach, functional dependence between the determining elements was both applied to the description of such processes that were commonly called causal and those in which an allegedly teleological feature was present. The stability of a network – or system – of such dependencies guaranteed the integrity of a fact. Frank, in 1932, thus wondered why all the system and Ganzheit talk was considered as genuinely biological. Similar features existed throughout mechanics. The main problem in the 1930s was however the notion of statistical law. Once again, Mach’s liberal notion of causality permitted Frank and others to consider statistical laws as genuine laws. Yet some physicists – when comparing classical causality with quantum mechanics – diagnosed a return of spontaneity in the quantum realm and considered the integrity of the experimental set-up emphasized by the Copenhagen Interpretation as a new Ganzheit. Frank again insisted that these features could be accommodated by a suitably understood law of causality, relegating the remainder of such talk to metaphysics. Nagel instead departed from a narrower conception of causality that integrated statistical laws into explanation, but was not as broad as Mach’s functional dependences. In the Structure of Science he adapted Bertalanffy’s system theory to serve as a model of systemic causality and in ‘Teleology Reviseted’ he considered the concept of a homeostat as the paradigm for a system-property approach of teleological explanation. In contrast to recent work by Jeffrey McDonough (2008) I emphasize that Nagel’s approach differs from Leibniz’s formal teleology by searching for an empiricist complement to causal explanation, not an independent concept of teleology.