The Nature of Science 5logic of the scientific method. Science is not about final truth or “facts”; it is only about con-
tinually testing and trying to falsify our hypotheses until they are extremely well supported.
At that point, the hypothesis becomes a theory (as scientists use the term), which is a well-
corroborated set of hypotheses that explain a larger part of our observations about the world.
Some well-known and widely accepted theories are the theory of gravitation, the theory of
relativity, the germ theory of disease, and of course, the theory of evolution.
As people, scientists must use common speech as well. An observation or explanation
that is extremely well supported is a fact in everyday language (even though we technically
cannot use the term within science). As we will discuss below, the evidence supporting the
hypothesis that life has evolved (and is still evolving now) is so overwhelming that it is a
fact in popular parlance. But the bigger problem is the different usages of the word “theory.”
As we just explained, to a scientist, a theory is an extremely well-supported framework of
hypotheses that explains a large part of nature. But the public uses the word entirely differ-
ently to describe some sort of wild idea or harebrained guess or conjecture, such as theories of
how and why John F. Kennedy was assassinated, or how aliens landed in Area 51 in Nevada
or Roswell, New Mexico, and the entire episode was covered up by the U.S. government.
This confusion between the scientific and vernacular use of the same word has been a
common problem with misunderstanding what evolution is about. As Isaac Asimov put it,
“Creationists make it sound as though a ‘theory’ is something you dreamt up after being
drunk all night.” For example, then-presidential candidate Ronald Reagan (speaking about
FIGURE 1.2. Not all swans are white. This is the Australian black swan. (Photo by the author)