Biology Reference
In-Depth Information
on the observation that many cases - perhaps most in the biomedical sciences -
lie somewhere in the middle between these two poles.
To make this picture more precise, he explicitly recognizes a temporal com-
ponent. We begin with the original reduced and reducing theory, or model, T
R
and T
B
. These are associated with their respective, 'corrected' versions, T
R
∗
and
T
B
∗
. For reduction to occur, four general conditions must then be in place:
(1) Connectability. The primitive terms of the reduced theory T
R
∗
must be
'associated with' terms within the reducing theory T
B
∗
.
(2) Derivability. The principles of T
R
∗
must be derivable from T
B
∗
, perhaps
supplemented with new correspondence rules.
(3) Enhanced precision. T
R
∗
should make more precise predictions than did T
R
;
and, perhaps, T
B
∗
makes more accurate predictions in the domain of T
R
than
did T
R
itself.
(4) T
R
and T
R
∗
are 'strongly analogous', and so even when T
R
is replaced by T
R
∗
,
given derivability, there is a clear sense in which T
R
is explained by T
B
∗
.
Models of reduction with a similar import, though differing significantly in
details, have been elaborated by Clifford Hooker (1981) and John Bickle (1998).
It is often worthwhile to make general models concrete. When we further
focus on
E. coli
in Section 3, the case of the
lac
operon will be a case in point as
a splendid exemplar of a mechanistic model within the biological sciences. And,
among others, Schaffner treats it that way. It is what he calls a 'theory of the
middle range' (1993, p. 98). Theories of the middle range are really paradigms
for what has since been called 'mechanistic' models. These are typically models
which describe a process. They explain the process in terms of the behavior and
organization of components, and they do so in dynamic terms. These models
are, moreover, idealized, and implicate entities at more than one level.
Having elaborated his model for the reduction of theories of the middle range,
here is what Schaffner says concerning the
lac
operon model:
Though reduction was not the aim of Jacob and Monod's work, significant
progress toward a complete chemical explanation of enzyme induction has been a
consequence of their research.
(1993, pp. 481-482)
Indeed, Schaffner is not always so modest, claiming later that 'the kind of
reduction exemplified by the operon theory' is a 'paradigm of the reduction of
biology to physics and chemistry' (1993, p. 487; cf. Schaffner, 1993, pp. 76-82,
160-165, 481-487). Similarly, Sarkar, in an insightful series of essays concerned
with reduction and reductionism in biology, describes the
lac
operon as a 'superb
example of strong reduction' (1998, p. 140; cf. pp. 55ff.). In cases of strong
reduction, explanations of systemic behavior can be constructed entirely on
