Chemistry Reference
In-Depth Information
2 theories
are cognitive objects with iconic properties referring to picturable but
presently not observable entities like bacteria and X-ray stars, and
type 3 theories
are cognitive objects with mathematical properties which refer to non-picturable
and unobservable entities,
like neutrinos and quarks.
36
According to Harr
´
'
s
scheme Gomberg
s substance - particularly the solid - seems to belong to the
type 1 entities - at first sight. Taking a closer look we realize that this object-
centered view might lead to a distorted picture of the chemical stuff which this
substance is: the solid is observable but not a radical, the dissolved material is no
longer observable but might be (and is) described as radical. Thus, if we try to
address this entity which tentatively is assigned as radical we could denote it to the
type 2 entity kind, and the relation of the two Gomberg described as a chemical
equilibrium.
What seems to be peculiar for chemistry is the priority of entity-realism over
theory-realism: long before an appropriate theoretical representation was developed
chemists denoted their scientific objects as radicals. To put it in other words: the
discovery of “triphenylmethyl” has not been the result of theory-driven activities.
After the “anomaly period” initiated by Gomberg the whole community of
chemists slowly took over the belief in radicals both as
theory
(
truth
)
realists
and
as
entity realists
. Chemists began to believe in the existence of free radicals because
Gomberg and others could present evidence for a
single bond trivalency
of carbon
atoms in one very special case (and later for related or derived cases as well).
Trivalency alone of course is not a necessary condition for a radical configuration,
see the (to use modern terms) double and triple bonds in hydrocarbons and carbon
monoxide, CO. As to triphenylmethyl, however, trivalency must result in three
single bonds at the central carbon atom and this conclusion destructs the constant
valency concept. However, the growing belief of the chemical community did
indeed refer to the contemporary radical concept. This concept was dominated by
the valency theory in general and the quadrivalency doctrine in particular. At least
the trivalency part of Gomberg
'
s results, which was a surprising “amendment”
of the old point of view, has been accepted after many experiments and hard
discussions. There was no reason to skip quadrivalency in general, but after 1900
we observe a decreasing support of the former canonic view that carbon atoms
must
comprise four bonds in their molecules. Only very few worried about the “down-
grade” of their former belief which in fact was considered as an accommodation of
theory to empirical facts rather than a revolution.
37
If - in a Kuhnian sense - a part
of the described historical episode is to be called a
crisis
, it is the very part of the
difficulties to find a proper characterization for the reaction products. In retrospect,
it certainly was a breakthrough and after the new concept was established and new
research directions opened the old normal science proceeded. Although Gomberg
'
s
'
36
Harr´
1986
, 70-71. The author claims that the vast majority of scientific theories are of type 2.
37
A fact that lets the approach of constructive empiricism of Bas van Fraassen appear sympathetic,
because to care for empirical adequacy is less ambitious than to change his or her belief whenever
a theory develops or changes. Cf. van Fraassen
2001
.
