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Why We Believe: Fostering Scientific Thought
because of the pronouncements of authorities. This type of material is useful when students
learn about the development of theory and the need to base it on empirical data.
According to Peirce (1877), astute thinkers and observers can go beyond using authority
to fix their beliefs. Such people “cannot help seeing that it is the mere accident of their
having been taught as they have, and of their having been surrounded with the manners
and associations they have, that has caused them to believe as they do and not far differently”
(¶ 28).
The a Priori Method
Sometimes people establish beliefs because those beliefs seem to make the most sense or are
“agreeable to reason.” Unfortunately, as Peirce (1877) pointed out, the beliefs arise in the
absence of fact. The fixing of such belief leads to induction, but at its basis, its assumptions
are based on convention or on the current fashion of thought. As such, Peirce said, this
method resembles that of authority, although perhaps without the forced compliance.
One example involves the question of why people catch colds. The popular belief is that
exposure to cold weather causes colds; the scientific view is that viruses are to blame.
Classic research has shown no link between temperature and colds (e.g., Douglas, Lindgren,
& Couch, 1968), and medical personnel appear confident that exposure to the cold does
not lead to colds: “That question has been answered many times. Chilling does not hinder
your immunity as long as you aren’t so cold that your body defenses are destroyed” (Mirkin,
2007, ¶ 3).
Some recent research (Johnson & Eccles, 2005) has suggested a link between having
one’s feet chilled in cold water and catching a cold, but those who developed colds reported
catching more colds to begin with, so it is not clear whether the cold water was instrumen-
tal in their development of symptoms. Based on the published evidence, there seems to be
as much evidence against the cold–cold link as for it.
In fact, a good critical thinking question involves why there is so little evidence for a
link between temperature and catching a cold if there is, in fact, a connection. Several
studies show no association; they could be victims of Type II errors—if an analysis has
insufficient power, for instance, a valid association may not be apparent. The one study
that shows the link may have arisen due to a Type I error—for unknown reasons, the par-
ticipants in the chilled group may simply have caught colds. Given the so-called file drawer
problem (Rosenthal, 1979), wherein researchers put nonsignificant results away in their
file drawers because of the publication bias toward significant effects, there may be any
number of studies that failed to find a cold–cold link.
The beliefs may be based on currently fashionable ideas and may show a degree of
consistency. But the a priori method is an insufficient basis for holding one’s knowledge.
The Scientific Method
Ultimately, the best approach to critical thought, at least as most psychologists suppose, is
the scientific method in which fact and evidence dominate. As Peirce (1877) described it,
“I may start with known and observed facts to proceed to the unknown (¶ 33).”