1 The Birth of Science - MSRI

154 6. The Hellenistic Scientific Method
), as Archimedes says, by deducing from them the planetary motions
actually observed.
The passage in Aristotle’s Physics that mentions natural selection22 is SL: make sure page range
is nontrivial
apparently similar in spirit to Aristarchus’. The “hypothesis” that animal
organs may in the beginning have had accidental shapes, like the
Aristarchan “hypothesis”, is not directly verifiable and appears at first
to flagrantly contradict observations — here the complex and functionally
well-adapted structures seen in animals. And yet, by drawing all the consequences
of that hypothesis, because only the more suitable forms would
have allowed survival and reproduction, one manages to explain much
more than through an appeal to final causes. Indeed, one can explain not
only the shapes of the organs based on their functions, but also why organs
are adapted to their functions, just as Aristarchus succeeded not only in
accounting for the apparent motion of fixed stars and the sun, but even in
explaining planetary retrogression.
6.4 Definitions, Scientific Terms and Theoretical Entities
Anyone who has used the term trapezium (or trapezoid) in school was never
in doubt that it describes a geometric figure rather than a concrete object.
Euclid’s students, to designate the same geometric figure, used the term
, from which we derive ours. But to them, the word was also part
of the ordinary language: it meant a stool or small table. The abstraction
process through which it came to designate a theoretical entity, therefore,
was necessarily more conscious and explicit. As Bruno Snell wrote:
The relation between language and the formation of scientific concepts
. . . can, strictly speaking, be observed only in Greek, because
only here did the concepts grow organically from the language. Only
in Greece . . . was there a native formation of scientific terms — all
other tongues fed on Greek, borrowed from it, translated from it or
depend on it in some less direct way. 23
To create a “scientific term” the Greeks resorted to one of two methods.
The first and more obvious to us was through a definition ().
In the history of thought, two profoundly diverse notions of definition
have alternated. According to the first, which we will call essentialist or Platonist
because we find it in Plato (though also in Aristotle), the purpose of a
22 See pages 137–138.
23 [Snell], p. 199.
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