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discovery, both Griffith and Driesch are discoverers. Based on the doctrine of
theory-ladenness of observation, however, neither Griffith nor Driesch is a
discoverer.
Furthermore, the Kuhnian view suggests that scientific discoveries usually occur
over a period of time and involve a number of scientists. Therefore, discoveries
should be regarded as collective rather than individual achievements. In this sense,
Griffith's experiment was nothing but part of the collective discovery of transfor-
mation and the “transforming principle,” and Driesch's was part of the collective
discovery of conditional specification. Such a view is plausible; however, it seems
to reject the concept of experimental discovery and indicates that neither Griffith
nor Driesch made a discovery by experiment. Yet it is not clear how much they
contributed to the two collective discoveries. From a historical perspective, we
want to know how to precisely assess their role in the related discoveries. From a
philosophical perspective, we wonder whether there are events or activities that can
be qualified as experimental discoveries. The answer to the historical question may
rely on the solution to the philosophical one.
3 Historical Controversies About Mendel's Discovery
Almost all textbooks of biology or genetics honor Mendel as the father of classical
genetics, because he was regarded as the discoverer of the first two fundamental
laws of heredity:
the law of segregation
(or
Mendel's first law
) and
the law of
independent assortment
(or
Mendel's second law
)
.
The fist law states that the two
copies of a gene segregate (or separate) from each other during transmission from
parent to offspring (Brooker
2009
, p. 23). The second law states that two different
genes will randomly assort their alleles during the formation of haploid cells
(Brooker
2009
, p. 27). However, almost every textbook provides different
formulations for the two laws.
6
Scientists have continued to rewrite them by adding
new terms and concepts from later theories of genetics (see Villee et al.
1989
;
Watson et al.
2004
; Hartl and Jones
2005
). How was Mendel supposed to discover
the two laws by his experiments on plant hybrids?
In the beginning, Mendel thought that “the value and validity of any experiment
are determined by the suitability of the means used as well as by the way they are
applied” (Mendel
1966
, p. 3). The experimental object, pea, was selected because it
possesses constant differing traits in the shape of the ripe seeds (round vs. wrin-
kled), in the position of flowers (axial vs. terminal), in the length of stem (long and
short), and so on. Mendel treated each plant having a distinct trait as a form and then
6
Take the formulations from Villee et al. (
1989
) as an example. In this textbook, the first law is
formulated as “when gametes are formed, the genes behave like particles, becoming separated so
that each sex cell (egg or sperm) contains only one member of each pair” (Villee et al.
1989
,
p. 242). The second law is formulated as “[A]lleles of two or more different loci are distributed
randomly with respect to one another during meiosis” (Villee et al.
1989
, p. 252).
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