If nothing happens by chance, but everything in nature follows a
definite order, and if the laws of nature embody that which we have been
able to learn about the order of nature in accurate language, then it
becomes very important for us to know as many as we can of these laws of
nature, in order that we may guide our conduct by them.
Any man who should attempt to live in a country without reference to the
laws of that country would very soon find himself in trouble; and if he
were fined, imprisoned, or even hanged, sensible people would probably
consider that he had earned his fate by his folly.
In like manner, any one who tries to live upon the face of this earth
without attention to the laws of nature will live there for but a very
short time, most of which will be passed in exceeding discomfort; a
peculiarity of natural laws, as distinguished from those of human
enactment, being that they take effect without summons or prosecution.
In fact, nobody could live for half a day unless he attended to some of
the laws of nature; and thousands of us are dying daily, or living
miserably, because men have not yet been sufficiently zealous to learn
the code of nature.
It has already been seen that the practice of all our arts and
industries depends upon our knowing the properties of natural objects
which we can get hold of and put together; and though we may be able to
exert no direct control over the greater natural objects and the general
succession of causes and effects in nature, yet, if we know the
properties and powers of these objects, and the customary order of
events, we may elude that which is injurious to us, and profit by that
which is favourable.
Thus, though men can nowise alter the seasons or change the process of
growth in plants, yet having learned the order of nature in these
matters, they make arrangements for sowing and reaping accordingly; they
cannot make the wind blow, but when it does blow they take advantage of
its known powers and probable direction to sail ships and turn
windmills; they cannot arrest the lightning, but they can make it
harmless by means of conductors, the construction of which implies a
knowledge of some of the laws of that electricity, of which lightning is
one of the manifestations. Forewarned is forearmed, says the proverb;
and knowledge of the laws of nature is forewarning of that which we may
expect to happen, when we have to deal with natural objects.
11. =Science: the Knowledge of the Laws of Nature obtained by
Observation, Experiment, and Reasoning.=
No line can be drawn between common knowledge of things and scientific
knowledge; nor between common reasoning and scientific reasoning. In
strictness all accurate knowledge is =Science=; and all exact reasoning
is scientific reasoning. The method of =observation= and =experiment= by
which such great results are obtained in science, is identically the
same as that which is employed by every one, every day of his life, but
refined and rendered precise. If a child acquires a new toy, he observes
its character and experiments upon its properties; and we are all of us
constantly making observations and experiments upon one thing or
another.
But those who have never tried to observe accurately will be surprised
to find how difficult a business it is. There is not one person in a
hundred who can describe the commonest occurrence with even an approach
to accuracy. That is to say, either he will omit something which did
occur, and which is of importance; or he will imply or suggest the
occurrence of something which he did not actually observe, but which he
unconsciously infers must have happened. When two truthful witnesses
contradict one another in a court of justice, it usually turns out that
one or other, or sometimes both, are confounding their inferences from
what they saw with that which they actually saw. A swears that B picked
his pocket. It turns out that all that A really knows is that he felt a
hand in his pocket when B was close to him; and that B was not the
thief, but C, whom A did not observe. Untrained observers mix up
together their inferences from what they see with that which they
actually see in the most wonderful way; and even experienced and careful
observers are in constant danger of falling into the same error.
Scientific observation is such as is at once full, precise, and free
from unconscious inference.
Experiment is the observation of that which happens when we
intentionally bring natural objects together, or separate them, or in
any way change the conditions under which they are placed. Scientific
experiment, therefore, is scientific observation performed under
accurately known artificial conditions.
It is a matter of common observation that water sometimes freezes. The
observation becomes scientific when we ascertain under what exact
conditions the change of water into ice takes place. The commonest
experiments tell us that wood floats in water. Scientific experiment
shows that, in floating, it displaces its own weight of the water.
Scientific =reasoning= differs from ordinary reasoning in just the same
way as scientific observation and experiment differ from ordinary
observation and experiment—that is to say, it strives to be accurate;
and it is just as hard to reason accurately as it is to observe
accurately.
In scientific reasoning general rules are collected from the observation
of many particular cases; and, when these general rules are established,
conclusions are deduced from them, just as in every-day life. If a boy
says that “marbles are hard,” he has drawn a conclusion as to marbles in
general from the marbles he happens to have seen and felt, and has
reasoned in that mode which is technically termed =induction=. If he
declines to try to break a marble with his teeth, it is because he
consciously, or unconsciously, performs the converse operation of
=deduction= from the general rule “marbles are too hard to break with
one’s teeth.”
You will learn more about the process of reasoning when you study
=Logic=, which treats of that subject in full. At present, it is
sufficient to know that the laws of nature are the general rules
respecting the behaviour of natural objects, which have been collected
from innumerable observations and experiments; or, in other words, that
they are inductions from those observations and experiments. The
practical and theoretical results of science are the products of
deductive reasoning from these general rules.
Thus science and common sense are not opposed, as people sometimes fancy
them to be, but science is perfected common sense. Scientific reasoning
is simply very careful common reasoning, and common knowledge grows into
scientific knowledge as it becomes more and more exact and complete.
The way to science then lies through common knowledge; we must extend
that knowledge by careful observation and experiment, and learn how to
state the results of our investigations accurately, in general rules or
laws of nature; finally, we must learn how to reason accurately from
these rules, and thus arrive at rational explanations of natural
phenomena, which may suffice for our guidance in life.