Physics Approach to Theistic Science

Dispositions in Nature and Physics

In order to advance Theistic Science, we need to discuss several key concepts and ideas concerning nature and physics. Only then can see see how theism and physics form a unified picture. 

These ideas are 

  1. that natural objects can have real dispositions, 
  2. that it is coherent to talk of 'dispositions according to what is actual', 
  3. that meaning can be given to the term ' derivative disposition'.
Explanations therefore start with the meaning of the term 'disposition', and the observation that dispositional properties can never be reduced to entirely static or formal structural properties. Their explanation must always involve some irreducibly 'causal' feature of some kind: some dynamic (rather than static) property. 

Dispositions, and their categorical irreducibility

I will be using the terms 'power', 'potential', 'capability', 'capacity', 'propensity' and 'cause' as examples in the category of dispositional properties of objects[11]. The power of an acid to dissolve a metal, for example, is a dispositional property. It says what would happen if certain circumstances occurred, namely that the acid was put in contact with the metal at a suitable temperature. The electric and gravitational potentials are measures of capacities to exert forces, should a suitable test particle be present. We normally believe the the dissolving powers of acid and the potentials of electric charges are still present even if metals or test particles are not present, and then seek to explain these dispositional properties in terms of some feature of the object (acid or electric charge) that gives rise to them. 

We must note, however, that this explanation of dispositional properties only explains or reduces them to other dispositions, and not to entirely static or structural properties. For suppose that the exact shape and size of a pencil were known, along with all the shapes and sizes of all its atomic parts, but no information about the dispositions of these parts. We would still know nothing about how the pencil would change with time or on interactions. In fact, if it and its parts had no dispositional properties, as Hume wants to argue, then we have his conclusion that any actions or changes (apart perhaps from uniform motion) would be entirely inexplicable: there would be nothing about the pencil that could lead to these changes rather than any others. This categorical irreducibility of dispositions was seen clearly by Aristotle and Leibniz, and has been explained at some length recently by Leclerc[ 3], Taylor[12], Mellor[ 13], Harre & Madden[10], and Emmet[ 14]. According to Shoemaker[15], the continued identity of objects also depends on their causal properties. There seems no way to avoid[16] the conclusion that something like dispositions are a fundamental part of any physical explanation. Therefore, for the purposes of this paper, I take the reality of dispositional properties to be philosophically plausible, even though their exact features are not deducible a priori, and must be the subject of empirical (scientific) investigations. 

Dispositions in Physics

Dispositions first appear in physics as the macroscopic features of observable objects that we wish to explain. Dispositional properties are largely those which cannot be explained purely by the location and shape of these objects, but require causal kinds of ascriptions and analyses, as explained above, in terms of causal powers. Thus the elasticity of a solid, for example, is explained in terms of the attractions between the electrons and their neighbouring atoms. Note that it is not enough to say that the elasticity can be explained simply in terms of the 'electronic structure', as purely structural properties cannot explain dispositional features without assuming some dispositions (such as charge, mass etc.) inherent in the electrons themselves. This irreducibility of causal explanation in physics has been discussed in detail elsewhere[9]. 

Physics should contain not only a phenomenological description of causes[17], but also a mathematical foundation that determines causes according to actualities. In Newtonian physics 'according to what is actual' means 'according to the spatial shape and configuration of the atomic particles'. In quantum mechanics 'actuality' means 'the quantum numbers of the most elementary particles, and also the definite past events that determine the current quantum state'. 

A distinction is being made between the 'Principal Cause' (that disposition which operates), and the 'Instrumental Cause' (that circumstance by means of which dispositions operate). Principal causes operate according to instrumental causes. Both are necessary for any action, for example, when a stone is let fall: the principal cause is the earth's gravitational attraction, and the instrumental cause is our action of letting go. Its hitting the ground is thus caused by our letting go, but only as an instrumental cause. Many common uses of 'cause' refer to instrumental causes rather than principal causes, as it is only in the instrumental sense that events can be said to be causes. The distinction between principal and instrumental causes will be very important, as thestic science will claim that God is the original principal cause of all events. Principal causes cannot operate without suitable conditions and actual circumstances (i.e. without suitable instrumental causes), and theistic science will want to see that the selection of which principal causes can operate must depend on which instrumental causes are actually present. 
 

Dispositions, Tendencies and Propensities

Dispositions is a general class, of which tendencies are 'sure fire' examples, and 'propensities' are probabilistic dispositions. 
 

Further Discussion


The essential role of dispositions (potentials, forces, propensities, etc) in physics is argued further in my article Real Dispositions in the Physical World published in British Journal for the Philosophy of Science, Vol 39, pp 67-79 (1988).