1 The Birth of Science - MSRI

6.6 Postulates and the Meaning of “Mathematics” and “Physics” 169
to finding “hypotheses” capable of saving the phainomena; he does not
aspire to know the absolute truth, whose pursuit is left to the natural
philosopher (or “physicist”). This situation is, as we have already seen, a
necessary consequence of the scientific method (or mathematical method, page 216
as it would be called then). Indeed, if two theories, based on different hypotheses,
are both consistent and explain equally well what is observed,
the choice between them is not within the purview of the scientist as such.
This does not mean that scientists necessarily reject the existence of ultimate
truths or global explanations; they may accept such theses characteristic
of natural philosophy. But the scientific method, shared by scientists
regardless of philosophical outlook, has a different goal: to develop theoretical
frameworks useful in describing the phainomena and in advancing
technology.
This was still quite clear to Thomas Aquinas, who, taking up again Simplicius’
contrast between “physics” and “astronomy” and the example
about eccentrics and epicycles, writes:
Reason may be employed in two ways to establish a point: firstly,
for the purpose of furnishing sufficient proof of some principle, as
in natural science [physica], where sufficient proof can be brought
to show that the movement of the heavens is always of uniform
velocity. Reason is employed in another way, not as furnishing a sufficient
proof of a principle, but as confirming an already established
principle, by showing the congruity of its results, as in astronomy the
theory of eccentrics and epicycles is considered as established, because
thereby the sensible appearances of the heavenly movements
can be explained; not, however, as if this proof were sufficient, forasmuch
as some other theory might explain them. 72
Thomas Aquinas is obviously using the word physica still in the classical
sense of philosophy of nature. He still knows the ancient scientific
method. That ancient science renounces all claim to an unambigous identification
of true first principles establishes, in his eyes, its inferiority with
respect to natural philosophy and theology. page 217
72 Thomas Aquinas, Summa theologica, part I, question 32, article 1, reply to objection 2. The translation
is by the Fathers of the English Dominican Province (Benziger Brothers, 1947), except that
“astrology” has been replaced by “astronomy”.
Revision: 1.7 Date: 2002/09/14 23:17:37