A comparative study of models for predation and parasitism

the model. The mathematical model refers to the equations or other relationships
that provide the quantitative predictions of the model. The material model is the
arrangement and interactions of fundamental particles, their fields and aggregates.
When a writer refers to the 'Bohr model of the hydrogen atom', he may have in
mind any or all of these aspects; the reader must select the aspects appropriate to
the context."
WALKER'S broad usage of the word includes, in later chapters of his book, the
MENDELIAN law of inheritance and the DARWINIAN theory of natural selection as
models. Clearly, the word 'model' in WALKER'S sense is used to categorize similar,
but distinctly different notions in a single, convenient, descriptive term. This catego.
rization may at times be needed in scientific communication, but I would rather use
the word in a much restricted sense in this paper, in order to emphasize the role of
a certain type of model that distinguishes itself from other similar notions, e.g.
'assumptions', 'hypotheses', 'theories', or 'descriptions' of laws and rules.
A dictionary (e. g. The WEBSTER's Third International Dictionary, 1968) treats
the word as a synonym for : Example, Pattern, Exemplar, Paradigm, Ideal, etc.; or it
is something perfect of its kind. The dictionary also states that a model is: a thing
that serves as a pattern or source of inspiration for an artist or writer; or an analogy
used to help visualize, often in a simplified way, something that cannot be observed
directly. The last definition is particularly important and most relevant to my investigation.
WALKER further stated that "the main purpose of a model is to make predictions",
and that "if a mathematical model predicts future events accurately, there is no necessity
for any interpretation or visualization of the process described by the equation."
These statements should be interpreted with caution, however. If they are taken
literally, it might be concluded that the purpose of an assumption, hypothesis, theory,
etc. is to predict but not to aid understanding of natural order: that is to say,
WALKER'S statement might be taken erroneously as synonymous with 'the aim of
science is predictions'. TOULMIN (1961) pointed out that the ancient Babylonian
astronomers who predicted the motion of stars amazingly accurately by arithmetic
means failed to understand underlying mechanisms, while the Ionian philosophers'
crude model of the universe eventually led to 20 th-century physics.
The understanding of natural order is achieved through the formation of new
concepts. SCHON (1967) emphasized the role of metaphor in the formation of a new
concept, through which a novel idea or discovery was made. He maintained that the
new concept would emerge by shifting already existing concepts to a new situation
by metaphor. That is to say, the old concepts, shifted to the new situation by metaphor,
are models for the new concept. If we use the word 'model' in a similar way,
and I am inclined to do so here, then some of WALKER'S examples should be excluded.
For example, the DARWINIAN theory can be a model if its principle is shifted