The Scientific Method
©2013 Robert Chuckrow
The Purpose of Science
The Purpose of Science is to explain, predict, and
establish cause and effect (e.g., forensics, medicine,
nutrition). Laws explain on a low level, and they
predict. Theories explain and predict laws, plus they
make additional, unexpected predictions.
The Verifiability Theory of Meaning:
• If a statement is incapable of being proven either true
or false, it has no meaning in the realm of science
and is inadmissible as a scientific statement.
• An example of a scientifically meaningless statement
(cannot be tested) is: “When I hold a stick in a northsouth direction it has one length. When I hold it in an
east-west direction, it doubles in size.” This statement
cannot be tested because to measure the stick in
each direction requires a ruler, which would also
change correspondingly and show no change.
Scientific Terms
• Hypothesis. A hypothesis is a tentative statement. If
the hypothesis is corroborated, conclusions may be
drawn from it. If the hypothesis is shown to be false, it
is abandoned or modified—or conclusions may be
drawn based on its falsity.
• Law: A law is a generalization, often in mathematical
form, about the behavior of a class of natural
phenomena. The statement, “Copper is shiny,”
though true, is not general enough to be a law.
Additional Scientific Terms
• Theory: A theory is collection of suppositions to
which analytic reasoning is applied for the purpose of
predicting and explaining one or more laws. Theories
start with postulates, which are assumptions that are
assumed to be true without a need for direct proof.
The truth of the postulates is borne out by the
success of the theory in explaining and predicting not
only the law but new phenomena. Theories are not
thought of as true or false. If the theory is useful it is
accepted, and if it is not useful it is not accepted.
• Postulate: A postulate is a statement that serves as
a basic assumption of a theory. Its truth can be
verified only indirectly, through consequent
predictions by the theory. A postulate is an
assumption that does not have be directly testable
but, combined with other such postulates and
mathematical reasoning, gives rise to assertions that
are directly testable.
A Statistical Study is Insufficient to
Establish Cause and Effect.
Statistical studies, if not erroneously done or purposely manipulated, only show a relationship worthy
of further investigation. For example, initial studies on
smoking during the 1960s showed a link between
smoking and lung cancer but lacked a mechanism
and, thus, did not establish a cause-and-effect relationship. Such a link is called constant conjunction
(think of other examples of constant conjunction).
Question: Can you think of explanations for the link
in the above example other than that smoking causes
lung cancer?
A Causal Relationship Requires
more than Constant Conjunction
• One requirement is to demonstrate mechanisms for
the link (e.g., later studies demonstrated evolving
lung-cell pathology in smokers and specific substances in tobacco smoke that produced such pathology.
• Another requirement is the ability to insert additional
links as more becomes known.
• Finally, the mechanisms must fit together with no
gaps or missing links.
Examples of Statistical Studies
• A study of shoppers in supermarkets concluded that
shoppers who use a shopping cart buy more than
those who don’t. Can you come up with an alternative
conclusion?
• A study concluded that people using credit cards
spend an average of 35% more than those who don’t.
Can you come up with an alternative conclusion?
• Another study: “Students who go to schools that
have a smaller number of students per class and are
taught by higher-paid teachers end up with higherpaying jobs than those who don’t.” Your comment?
Less-Obvious Pseudo Science
• The French drink lots of red wine and have a lower
incidence of heart disease. Red wine has
antioxidants, which protect the heart. Therefore, you
should drink red wine to prevent heart attacks.
• Discuss! See
http://www.chuckrowtaichi.com/RedWine.html.
Early Ideas about Matter
Around 450 BC, the ancient Greeks believed that that
everything was made up of earth, water, air, and fire.
Later Aristotle suggested that there was a fifth
element, aether, because the stars could not be
made out of earthly elements. This theory explained
but did not predict.
Non-Science Systems
• Astrology, while not a science, does explain
and makes predictions that seem to be
surprisingly accurate to many people.
• Traditional Chinese Medicine (TCM) is based
on 5,000 years of trial and error. It uses herbs
(thousands are used) and acupuncture to
improve the flow of ch’i, digestion, circulation,
and the immune system. In recent years, the
Chinese have been endeavoring to use
science to confirm its validity.