Chapter 7, page 157
How do you think the capital punishment supporter would respond? Two representative responses were:
It shows a good direct comparison between contrasting death penalty effectiveness. Using neighboring states
helps to make the experiment more accurate by using similar locations.It seems that the researchers studied a carefully selected group of states and that they were careful in
interpreting their results.Now—how would capital punishment supporters respond to the exact same study if the results were the
opposite, as shown here:
Palmer and Crandall compared murder rates in 10 pairs of neighboring states with different capital
punishment laws. In 8 of the 10 pairs, murder rates were higher in the state with capital punishment. This
research opposes the deterrent effect of the death penalty.Here are two representative responses by capital punishment supporters to this version of the study:
The evidence given is relatively meaningless without data about how the overall crime rate went up in those
years.There were too many flaws in the picking of the states and too many variables involved in the experiment as a
whole to change my opinion.The method of the study was unchanged. Only the results were different. And yet the responses were totally
different. Students found great fault with the study that opposed their views but found no problems with the
study that supported their views. The same pattern held for opponents of the death penalty: They found
flaws in the study when the results supported the death penalty and found no flaws in the study when the
results opposed the death penalty.
As this study illustrates, most people look hard for flaws in evidence that contradict their beliefs, but
they don’t look hard at all for flaws in evidence that support their beliefs (P. A. Klaczynski, 2000; Paul A.
Klaczynski, Schuneman, & Daniel, 2004; Kunda, 1990). In this way, their reasoning is biased rather than
fair-minded. Poor reasoners are biased in their evaluation of evidence. Good reasoners, on the other hand,
attempt to be more fair-minded in evaluating evidence (Chinn & Brewer, 1993).
Recall from Chapter 5 (prior conceptions), you learned about the various ways in which people
discount evidence that contradicts their beliefs. In doing this, people do not always evaluate evidence fair-
mindedly. Instead, they may evaluate evidence that contradicts their current beliefs with skepticism and
they may gloss over any possible flaws in evidence that supports their beliefs. As a teacher preparing
students to reason in the real world, one of your goals should be to promote more fair-minded reasoning.
The goal is for students to be able and willing to notice flaws in arguments that support their positions as
well as to avoid being too harsh in evaluating arguments against their positions.