Brief history
In his work ‘‘The History of Animals’’ the Greek philosopher Aristotle claimed
that men and women had a different number of teeth, and that their internal
organs were also different. These assertions were supported by long arguments.
No verification was sought and, indeed, Aristotle believed that none was
required, since the arguments were based on the author’s philosophy, which
was consistent and perfectly satisfactory. The possibility that these statements
might actually be wrong never occurred to Aristotle, nor did the thought that
careful observation and experimentation might be needed to decide the issue.
Early Greek philosophers (e.g. Thales of Miletus) noted that, in many
instances, Nature exhibits a regular behavior. Most noticeable among these
are, perhaps, the change of day into night and the progression of the seasons.
This eventually gave rise to the idea of natural phenomena being determined by a
set of rules, or by logical conclusions derived from these rules. The realization
that Nature is not driven by the whims of the gods marks the beginning of
science.
Accepting the existence of rules that describe the world around us, it is natural
to ask how can we best discover these rules. One possible method is to argue that
since the world around us can be explained by drawing conclusions from a set of
first principles, these first principles ought to be part of a coherent and logically
constituted philosophy. So all we have to do is guess the right philosophy, from it
the behavior of the whole of Nature can be deduced.
The notion that the properties of the world around us can be obtained from a
series of ideas, a philosophical edifice, is called the deductive method of reasoning.