Experimental Discovery, Data Models, and Mechanisms in Biology: An Example from Mendel’s Work - Mechanism and Causality in Biology and Economics - page 107

historians of biology may accept that Mendel did not discover the laws but insist
that he had an embryonic idea of the gene and therefore certainly played a key role
in classical genetics.
I accept that Mendel did not discover the two laws of heredity, nor did he have an
embryonic idea of the gene, but I argue that he definitely played a crucial role in the
research on heredity. Still, one may wonder, if Mendel had no embryonic idea of a
gene, in what sense can one say that Mendel's experimental work can be regarded
as a key? What did Mendel discover if he did not discover the laws? Could his
“discovery,” whatever it may be, be regarded as an experimental discovery?
4 What Did Mendel Discover?
I think that Alain Corcos and Floyd Monaghan ( 1993 ) convincingly analyzed
Mendel's discovery in their detailed explication of the entire text of Mendel's
“Verschue.” They first claimed:
A close study of his paper reveals that the laws of heredity, which are supposed to be there,
are not present. Instead, one finds a series of laws relating to the formation of hybrids,
which are entirely different from the traditional “Mendelian” laws of heredity. (Corcos and
Monaghan 1993 , p. xvi)
The two authors reconstructed the series of five laws from Mendel's original
text. However, one may find that they are more like “generalizations” than scientific
laws. Given also the fact that the notion of “a law” in biology is often questioned,
I will call Corcos and Monaghan's five laws “generalizations.” They are:
G1. The hybrid offspring of parents, each true-breeding for one of the contrasting
characters of a trait, are all alike and like one of the parents. No intermediate
types are formed. (Corcos and Monaghan 1993 , p. 81, p. 89, p. 97)
G2. Reciprocal fertilizations yield the same hybrid forms. That is, the hybrid trait
will be that of the dominating parent regardless of whether that is the seed
parent or the pollen parent. (Corcos and Monaghan, p. 81, p. 89, p. 97)
G3. When the hybrids are allowed to self-fertilize, the offspring always appear in
two classes: one class like the hybrids and like one of the original true-breeding
parents (the dominating); and one class like the parental character not visible in
the hybrid generation (the recessive). No intermediate forms are produced. The
two classes occur in the approximate ratio of 3 dominating to 1 recessive.
(Corcos and Monaghan, p. 89, p. 97)
G4. (a) When the recessive offspring of the hybrids are allowed to self-fertilize,
they always breed true. (b) When the dominating offspring of the hybrids are
allowed to self-fertilize, approximately one-third of them breed true while two-
thirds of them behave exactly like the hybrid generation. (Corcos and
Monaghan, p. 97)