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REGULARITY THEORIES OF CONSTITUTION COMPARED 127
(2007, 83) and Mandik (2011) seem to identify the notion with supervenience, i.e. a
relationship between classes of properties.
The most detailed definition of the term ‘mechanistic constitution’ has so far been developed
by Harbecke (2010) and Couch (2011), who independently of each other have defended a
regularity theory of mechanistic constitution. 1 The central idea of these approaches lies in the
assumption that mechanistic constitution can be defined in extensional language. The
authors transfer instruments successfully deployed in regularity theories of causation to the
definition of mechanistic constitution.
The current paper examines the precise relationship between the two regularity theories of
mechanistic constitution by analysing in detail their commonalities and differences.
Furthermore, an evaluation of strengths and weaknesses of the two alternatives is offered.
The investigation proceeds by the following steps: First the relevance of the problem for the
conceptual basis of neurobiological explanation is discussed (Section 2). Afterwards, the core
assumptions of Couch’s and Harbecke’s theories are presented (Section 3 and 4), before the
commonalities (Section 5) and differences (Section 6) of the approaches are investigated.
Section 7 contains an evaluation of the theories against the background of the preceding
investigations. Section 8 summarizes the results and makes some suggestions concerning
possible future research on regularity theories of mechanistic constitution.
2. On the Relevance of the Problem and the Method of Analysis
The general philosophical project in which regularity theories of mechanistic constitution are
embedded applies a particular methodology, which aims to establish philosophical
conclusions on the basis of a logical analysis of prototypical explanations in neuroscience. It is
then attempted to develop a structural model of successful explanations in neuroscience,
which is descriptively adequate as well as normatively binding. The contributions to this
project therefore typically reconstruct pertinent results of neuroscientific research and reflect
them philosophically. Harbecke reports a widely accepted theory of the localisation of the
cognitive function of spatial representation in the brain of rats (cf. T. Bliss und T. Lømo 1973;
Lømo, T. 2003; R. Morris 1984; R. Morris, E. Anderson, G. Lynch and M. Baudry 1986).
According to this theory, spatial representation in rats is constituted through a ‘neuronal
map’ in the hippocampus, which again is constituted by a long term-potentiation (LTP) of
pyramidal cells in area CA1 of the hippocampus, where the LTP of these cells is constituted
essentially through the activation of the NMDA-receptors at their synapses. The theory is
supported by various experiments, which have shown a correlation of an impairment of
spatial orientation - indicated through disorientation and ineffective food searching in an
experimental environment - and the blockade of NMDA-receptors or simply the surgical
removal of the hippocampus.
In this sense, the celebrated neuroscientific explanation of spatial representation in rats uses
the following four theoretical terms, whose referents are linked by mechanistic constitution:
1. Spatial Representation
2. Generating a neuronal ‘map’ in the hippocampus
3. LTP of pyramidal neurons
4. Activation of NMDA – receptors
1
Harbecke’s definition uses the term ‘mechanistic constitution’, whilst Couch chooses the notion of
‘constitutive relevance’. However, it is clear that both authors wish to define the same kind of relation.