Beyond Feelings

188 PART THREE A Strategy
are harmful to humans. Numerous experiments seemed to have settled
the matter. Then anthropologist Patricia Draper studied a southwest
African tribe of hunter-gatherers, the !Kung bushmen. Though their
land offers ample space to spread out their settlements and huts, they
crowd their dwellings together and often sit in tight groups, literally
brushing against one another. Yet they have none of the medical conditions
(such as high blood pressure) usually associated with crowding. 3
This one fact has caused reexamination of a scientific truism.
Because the aim of inquiry is to produce evidence, it will be helpful to
recall the guidelines presented in Chapter 6 for determining when evidence
is sufficient:
1. Evidence is sufficient when it permits a judgment to be made with certainty.
Wishing, assuming, or pretending that a judgment is correct
does not constitute certainty. Certainty exists when there is no
good reason for doubt, no basis for dispute. The standard for conviction
in a criminal trial, for example, is “guilt beyond a reasonable
doubt.” Certainty is a very difficult standard to meet,
especially in controversial issues, so you will generally be forced
to settle for a more modest standard.
2. If certainty is unattainable, evidence is sufficient if one view of the issue
has been shown to have the force of probability. This means that the
view in question is demonstrably more reasonable than any competing
view. In civil court cases, this standard is expressed as “a
preponderance of the evidence.” Demonstrating reasonableness is,
of course, very different from merely asserting it, and all possible
views must be identified and evaluated before any one view can
be established as most reasonable.
3. In all other cases, the evidence must be considered insufficient. In other
words, if the evidence does not show one view to be more reasonable
than competing views, the only prudent course of action is to
withhold judgment until sufficient evidence is available. Such restraint
can be difficult, especially when you want a particular view
to be proved superior, but restraint is an important characteristic
of the critical thinker.
Exactly how much inquiry is enough depends entirely on the issue. In
some cases, a brief inquiry will be more than adequate. In others, an exhaustive
inquiry will be incomplete. However, although no absolute statement
can be made about the amount of inquiry required, you can be reasonably
sure your inquiries are complete when you have made a thorough and careful
effort to learn the relevant facts and to consult informed opinion in all
fields of study that have a direct bearing on the specific issue you are analyzing.
The number of fields to be researched will, of course, vary with the
nature of the issue. Here, for example, is a list of the fields that have a direct
bearing on three specific issues we identified in Chapter 16: