1.2. The Scientific Method http://www.ck12.org
In ancient Greece, the basic approach to answering questions about the world was through discussion and debate.
There was very little gathering of information, and it was believed that the best way to answer fundamental questions
was through reasoning and talking. As a result, several ideas about matter were put forth, but these ideas could
not really be proven or disproven. For example, Thales of Miletus (~625-545 B.C.) believed that water was the
fundamental unit of matter, whereas Anaximenes (~585-525 B.C.) felt that air was the basic unit. Empedocles
(~490-430 B.C.) argued for the idea that matter was composed of earth, air, fire, and water. Each of these men had
reasons they could offer to support their theories, but there was no way to prove who was right.
The first major philosopher to gather data through observation was Aristotle (384-322 B.C., shown inFigure1.10).
He recorded many observations about the weather, the life and behaviors of plants and animals, physical motions,
and a number of other topics. Aristotle could potentially be considered the first “real” scientist, because he made
systematic observations of nature before trying to understand what he was seeing.
Although Aristotle contributed greatly to Greek knowledge, not all of his observations led to correct theories.
Leucippus (~480-420 B.C.) and his student Democritus (~460-370 B.C.) proposed some theories about matter that
Aristotle later opposed. Since Aristotle’s influence was so great, others chose to reject these theories in favor of
Aristotle’s ideas. However, it turned out that Aristotle was wrong and Leucippus and Democritus were right, but
at the time there was no method for proving or disproving these opposing theories. It took almost 2000 years for
people to reconsider this issue since Aristotle was held in such high regard by scholars.
FIGURE 1.
AristotleInductive and Deductive Reasoning
Two approaches to logical thinking developed over the centuries. These two methods areinductive reasoning
anddeductive reasoning. Inductive reasoning involves making specific observations, and then drawing a general
conclusion. Deductive reasoning begins with a general principle and a prediction based on this principle; the
prediction is then tested, and a specific conclusion can then be drawn.
The first step in the process of inductive reasoning is making specific observations. In the periodic table of elements,
which we will discuss later, there is a group of metals with similar properties called the alkali metals. The alkali
metals include elements such as sodium and potassium. If I put sodium or potassium in water, I will observe a very
violent reaction every time. I draw a general conclusion from these observations: all alkali metals will react violently
with water.
In deductive reasoning, I start with a general principle. For example, say I know that acids turn a special material
called blue litmus paper red. I have a bottle of vinegar, which I believe is an acid, so I expect the litmus paper to
turn red when I immerse it in the vinegar. When I dip the litmus paper in the vinegar, it does turn red, so I conclude
that vinegar is in fact an acid. You can see that in order for deductive reasoning to lead to correct conclusions, the