Reasoning
Inductive Logic
One collects results from a number of experiments and
extracts a general rule.
The general rule is formed from experimental results only,
not by extrapolation of basic principles.
Sir Francis Bacon (1561 - 1626) was probably the best
known proponent of this method of reasoning. In fact he
thought that all human knowledge could be found by
inductive logic.
Reasoning
Newton employed a combination of both modes of reasoning.
He used observations to construct theories and then generalized
the theories to deduce possible new phenomena.
If subsequent observations did not support the prediction
he modified the theory.
Reasoning
Deductive Logic
One starts with some initial principle or theory and
logically argues that certain results must follow.
Experiments are only used to verify the results.
Rene Descartes (1596 - 1650) believed that one could
not entirely trust observations and that it was more powerful
to start with a few irrefutable principles and derive from
them new knowledge.