Experimental Discovery, Data Models, and Mechanisms in Biology: An Example from Mendel’s Work - Mechanism and Causality in Biology and Economics - page 112

hypotheses. Therefore, producing the need and the motive to discover mechanisms
is an important function of experimental discovery .
Look at Mendel's case. Mendel himself postulated the existence of “elements”
to explain his experimental results. The speculation or imagination of elements
suggested an underlying mechanism in which elements engage in certain activities
to produce a fixed ratio in the number of offspring. Yet Mendel did not realize what
those elements were. Nonetheless, his speculation, based on his experimental
results, envisaged the need to disclose a hidden mechanism, and that need led
ensuing biologists to interpret his paper from the view of hard heredity. Explaining
data models of the formation of hybrids involves the transmission of traits, because
“hybrid” and “true breeding” are defined by the combination and recombination of
traits. This indicates that the search for a mechanism is a later step in the process
from Mendel's discovery to the development of Mendelian genetics. People can
thus recognize Mendel's findings as a genuine experimental discovery that is prior
to the discovery of Mendelian mechanism of heredity.
There are various characterizations of mechanisms in the philosophy of science.
The one I adopt was proposed by Peter Machamer, Lindley Darden, and Carl Craver
(hereafter MDC):
Mechanisms are entities and activities organized such that they are productive of regular
changes from start or set-up to finish or termination conditions. (MDC 2000 ,p.3)
In subsequent works, Darden and Craver have articulated the notion of mecha-
nism and have developed a philosophical theory, taking molecular biological and
neurobiological cases as examples (Craver and Darden 2001 ; Craver 2001 , 2002 ,
2005 ; Darden 2002 , 2005 , 2006 ). For the relation between mechanism and phe-
nomenon that is one of the central concerns of this chapter, MDC presented a
preliminary connection: “To give a description of a mechanism for a phenomenon
is to explain that phenomenon, i.e., to explain how it was produced,” and “The
organization of these entities and activities determines the ways in which they
produce the phenomenon” (MDC 2000 , p. 3). As for the meaning of phenomena,
Craver and Darden (2001, p. 122) advocated Bogen and Woodward's ( 1988 , p. 317)
argument that phenomena should not be confused with data. They agreed that a
phenomenon can be understood as follows: “We think of phenomena as relatively
stable and repeatable properties or activities that can be produced, manipulated, or
detected in a variety of experimental arrangements” (2001, p. 114). Craver and
Darden further pointed out that “different experimental arrangements reveal differ-
ent aspects of the phenomenon” (2001, p. 122). In addition, in discussing
“constraints on the organization of mechanisms,” Darden and Craver identified
“the characterization of phenomena” as a constraint on the search for mechanisms.
They concluded (2001, p. 123):
Characterizing the higher-level phenomenon to be explained is a vital step in the discovery
of mechanisms. Characterizing the phenomenon prunes the hypothesis space (since the
mechanism must produce the phenomenon) and loosely guides its construction (since
certain phenomena are suggestive of possible mechanisms).