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Reduction and Elimination in Philosophy and the Sciences

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On <strong>the</strong> Characterization of Objects by <strong>the</strong> Language of Science<br />

Paul We<strong>in</strong>gartner, Salzburg, Austria<br />

1. The Objects Described by <strong>the</strong> Laws of a<br />

Scientific Discipl<strong>in</strong>e<br />

In <strong>the</strong> natural sciences we usually make use of a twofold<br />

picture for <strong>the</strong> description of <strong>the</strong> observed phenomena: <strong>the</strong><br />

objects of experience <strong>and</strong> <strong>the</strong> laws of nature, where <strong>the</strong><br />

behaviour of objects is governed by <strong>the</strong> laws of nature. To<br />

give some examples: Newton’s laws of motion describe<br />

<strong>the</strong> spatio-temporal behaviour of mass po<strong>in</strong>ts. Kepler ’s<br />

laws determ<strong>in</strong>e <strong>the</strong> trajectories of planets <strong>in</strong> <strong>the</strong> solar system.<br />

The fundamental law of Quantum Mechanics, <strong>the</strong><br />

Schröd<strong>in</strong>ger equation, governs objects like atoms, electrons,<br />

neutrons … etc. Mendel’s laws rule <strong>the</strong> transmission<br />

of genes <strong>in</strong>to <strong>the</strong> next generation.<br />

These objects (mass po<strong>in</strong>ts, planets, electrons,<br />

genes … etc.) <strong>the</strong> behaviour of which is described by <strong>the</strong><br />

laws of nature cannot be <strong>in</strong>dividualised. For <strong>in</strong>stance mass<br />

po<strong>in</strong>ts are not <strong>in</strong>dividualised objects, but st<strong>and</strong> for any<br />

object possess<strong>in</strong>g mass; also <strong>the</strong> trajectories of Kepler ’s<br />

laws are not <strong>in</strong>dividualised, <strong>the</strong>y st<strong>and</strong> for any trajectory<br />

belong<strong>in</strong>g to a certa<strong>in</strong> category which obeys certa<strong>in</strong><br />

conditions like be<strong>in</strong>g periodical <strong>and</strong> hav<strong>in</strong>g a certa<strong>in</strong> type<br />

of stability 1 ; fur<strong>the</strong>r <strong>the</strong> objects like neutrons or electrons<br />

cannot be <strong>in</strong>dividualised by <strong>the</strong> Schröd<strong>in</strong>ger equation,<br />

s<strong>in</strong>ce this equation describes <strong>the</strong> behaviour of k<strong>in</strong>ds of<br />

elementary particles for example of electrons <strong>and</strong> of<br />

neutrons. Similarly Mendel’s laws do not dist<strong>in</strong>guish<br />

between <strong>in</strong>dividual genes transmitted but are concerned<br />

with classes or categories of genes.<br />

From this consideration it seems to follow that <strong>the</strong><br />

objects of science which are governed by <strong>the</strong> laws are<br />

always <strong>in</strong>complete <strong>in</strong> <strong>the</strong> sense of Me<strong>in</strong>ong. Even if this is<br />

correct, we have to po<strong>in</strong>t out however, that <strong>the</strong><br />

<strong>in</strong>completeness is only relative here.<br />

These objects are <strong>in</strong>complete w.r.t. to <strong>the</strong><br />

<strong>in</strong>dividualised object, but <strong>the</strong>y are not <strong>in</strong>complete w.r.t.<br />

what laws of nature describe. Thus for example it holds for<br />

<strong>the</strong> laws of Quantum Mechanics (for Schröd<strong>in</strong>ger’s<br />

equation) that <strong>the</strong>y are permutational symmetric<br />

(<strong>in</strong>variant). That means that “different <strong>in</strong>dividual” particles<br />

of <strong>the</strong> “same k<strong>in</strong>d” are treated identical by <strong>the</strong> law. Thus<br />

<strong>the</strong> laws <strong>and</strong> <strong>the</strong> respective physical reality described by<br />

<strong>the</strong>se laws rema<strong>in</strong> <strong>the</strong> same if we <strong>in</strong>terchange any two<br />

particles of <strong>the</strong> same k<strong>in</strong>d, for example two electrons. The<br />

same holds for protons, neutrons, neut<strong>in</strong>os <strong>and</strong> photons.<br />

Concern<strong>in</strong>g physical systems or states permutational<br />

<strong>in</strong>variance holds only for bosons not for fermions because<br />

<strong>the</strong> latter obey Pauli’s exclusion pr<strong>in</strong>ciple.<br />

What has to be underl<strong>in</strong>ed here is, that <strong>in</strong>variance<br />

properties of laws of nature are just <strong>the</strong> essential<br />

characteristics of what a law is. So let us move fur<strong>the</strong>r to<br />

<strong>the</strong> most important <strong>in</strong>variance of laws of nature: It is that<br />

<strong>the</strong> laws of nature are space time <strong>in</strong>variant. That means<br />

that <strong>the</strong> laws do not change with time, i. e. <strong>the</strong>y abstract<br />

from any particular po<strong>in</strong>t of time (translational <strong>in</strong>variance or<br />

translational symmetry) <strong>and</strong> <strong>the</strong>y do not change from one<br />

space po<strong>in</strong>t to ano<strong>the</strong>r, i. e. <strong>the</strong>y abstract from any<br />

1 For a detailed discussion of <strong>the</strong> conditions for dynamical (<strong>and</strong> also: statistical)<br />

laws see Mittelstaedt-We<strong>in</strong>gartner (LNt, 2005) ch. 7.<br />

particular space po<strong>in</strong>t. 2 From this it follows that laws of<br />

nature do not describe <strong>in</strong>dividualised objects. However a<br />

dynamical law describes <strong>the</strong> time development from an<br />

<strong>in</strong>dividual state of <strong>the</strong> system at t1 to an <strong>in</strong>dividual state of<br />

<strong>the</strong> system at t2. But this <strong>in</strong>dividual state at t2 is only<br />

derivable from <strong>the</strong> law (as a special solution of <strong>the</strong><br />

differential equation) if <strong>the</strong> state at t1 is known <strong>and</strong><br />

<strong>in</strong>stantiated; i.e. <strong>the</strong> later state is a def<strong>in</strong>ite function of <strong>the</strong><br />

earlier. In <strong>the</strong> case of statistical laws even this is not<br />

possible. Individual microstates cannot be used as an<br />

<strong>in</strong>stantiation: Statistical laws describe <strong>and</strong> predict only <strong>the</strong><br />

states of <strong>the</strong> whole system, <strong>the</strong> macrostates, which can be<br />

realised by a huge number of different microstates; i.e. no<br />

particular <strong>in</strong>dividual microstate is required, anyone of <strong>the</strong><br />

huge number will do. This means also that although <strong>the</strong><br />

microstates cause <strong>the</strong> macrostate, no particular microstate<br />

is a necessary condition for <strong>the</strong> macrostate.<br />

The result of this section is that <strong>the</strong> objects<br />

described by laws of nature 3 are not objects which satisfy<br />

uniqueness <strong>in</strong> <strong>the</strong> sense of Russell. Relative to <strong>in</strong>dividual<br />

objects satisfy<strong>in</strong>g uniqueness <strong>the</strong>y are <strong>in</strong>complete. But<br />

<strong>the</strong>y are not <strong>in</strong>complete w.r.t. laws, s<strong>in</strong>ce laws have to<br />

have <strong>in</strong>variance (or symmetry) properties as <strong>the</strong>ir essential<br />

characteristics. The question whe<strong>the</strong>r real particular<br />

objects of modern physics are complete <strong>in</strong> <strong>the</strong> sense of<br />

Me<strong>in</strong>ong or are <strong>in</strong>dividualised <strong>in</strong> <strong>the</strong> sense of satisfy<strong>in</strong>g<br />

uniqueness, will be treated below.<br />

2. Russell’s Ontological Presuppositions<br />

Concern<strong>in</strong>g <strong>the</strong> Objects of Reference <strong>in</strong> <strong>the</strong><br />

<strong>Sciences</strong><br />

2.1<br />

Names directly designate an <strong>in</strong>dividual (object) which is its<br />

mean<strong>in</strong>g. 4 That is <strong>the</strong> relation of denot<strong>in</strong>g, designat<strong>in</strong>g or<br />

referr<strong>in</strong>g is a two-place relation <strong>and</strong> reference is identified<br />

with mean<strong>in</strong>g. Russell drops <strong>the</strong> middle part of <strong>the</strong> Medieval<br />

Theory (also adopted by Me<strong>in</strong>ong):<br />

2.2<br />

name concept reference<br />

description conceptual construction object<br />

mean<strong>in</strong>g, content<br />

In Russell's underst<strong>and</strong><strong>in</strong>g, <strong>the</strong> relation of denotation (designation)<br />

or reference is <strong>the</strong> same if <strong>the</strong> objects of reference<br />

are ma<strong>the</strong>matical (conceptual) entities or physical<br />

objects; i.e. this relation is <strong>in</strong>dependent of whe<strong>the</strong>r <strong>the</strong><br />

relata are conceptual objects (which are nei<strong>the</strong>r spatial,<br />

nor temporal) or physical objects /(<strong>in</strong> space <strong>and</strong> time).<br />

2 If <strong>in</strong>stead of space po<strong>in</strong>t we speak of <strong>in</strong>variance w.r.t. mov<strong>in</strong>g reference<br />

systems <strong>the</strong> th<strong>in</strong>gs get more complicated. For details see Mittelstaedt-<br />

We<strong>in</strong>gartner (2005, LNt) ch. 6.<br />

3 For a detailed discussion see Mittelstaedt-We<strong>in</strong>gartner (2005, LNt) ch. 10.<br />

4 Cf. <strong>the</strong> quotation from Russell (1919, IMP), p. 174, note 3.<br />

383

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