Science in its widest significance is sometimes defined as the
correlation of all knowledge. In this sense it would include
_philosophy_. In a more restricted and generally accepted sense, the
term is applied to the _systematized_ divisions of knowledge.
Science and philosophy _resemble_ each other in so far as they both have
to do with knowledge; but while the latter deals with the whole sum of
knowledge and goes back to generalized first principles, the former
takes up special branches of it. That is, a science is such in fact when
a sufficient number of interrelated facts are so arranged and classified
by referring them to the general truths and principles on which they are
founded that they constitute a well-certified and more or less complete
branch of knowledge.
From the present development of knowledge the separate entities of the
universe are five--namely, ether, matter, energy, life, and mind. The
first three are inseparable agents in the simplest phenomena that occur
in nature. They may ultimately be reduced to two, or, conceivably, to
one. It is with these that the various branches of science have to
deal--to observe, to experiment, to classify, to define.
CLASSIFICATION OF THE SCIENCES.--The sciences may be grouped in two
ways. _First_, from what has been said above, they may be divided into:
(a) the _physical_ sciences, which have to do with inorganic
nature--that is with the laws and properties of matter, energy, and
ether;
(b) the _biological_ sciences, which consider the laws of life; and
(c) the _psychical_ sciences, which deal with the phenomena of mind.
_Second._--Another, and probably more practical, division is that of (a)
_pure_ or _theoretic_ sciences, and (b) _applied_ or _practical_
sciences. The latter consist of those branches which deal with facts,
events, or phenomena as explained, accounted for, or produced by means
of powers, causes, or laws; the former as the knowledge of these powers,
causes, or laws, considered apart or as pure from all applications. To
the class of pure or fundamental sciences belong mathematics, physics,
chemistry, psychology, and sociology; to the applied or concrete belong
geology, mineralogy, botany, zoology, meteorology, geography, ethics,
politics, law, jurisprudence, logic, grammar, rhetoric, philology, and
political economy; navigation, engineering, and practical mechanics;
surgery, medicine, materia medica, etc.
METHODS OF SCIENCE.--The great method of scientific inquiry is
experiment--the laboratory. Contrasted with _experiment_ is
_observation_. But even in astronomy, emphatically an observational
science, experiment plays an important part. The dynamical knowledge
which Newton developed into the cosmic law of gravitation was founded on
experiment. Meteorology, again, has made great strides in these days by
appealing to laboratory experiments for elucidation of its phenomena.
Likewise in biology, botany, and zoology experiment has led to striking
discoveries; while such branches as embryology and bacteriology are as
truly experimental as chemistry itself.
In the psychical group of sciences the method of experimenting still
awaits development. The complexity of the problems presented, and the
manner in which they affect the welfare and happiness of humanity,
render social and political experimenting excessively hazardous. Such
sciences as those studied by the economist, the ethnologist, the
moralist, or the theologian are of necessity essentially observational.