EVALUATING REASONING: THE NECESSARY SKILLS

The skills discussed in this chapter need to be used together when assessing a passage of
reasoning. We need to consider whether the reasons, and any unstated assumptions, are
true; whether anything which we ourselves know, but which is not stated in the passage,
weakens or strengthens the conclusion; whether, if the passage relies upon an explanation,
we can think of equally plausible alternative explanations; and finally whether we can
identify flaws in the reasoning which show us that the conclusion is not well supported by
the reasons. We also need to consider whether the argument relies upon evidence from
anyone whose authority is questionable. This is discussed in detail in Chapter 4, which also
contains exercises on evaluating evidence and authorities. Meanwhile, here is a summary
of the skills discussed in this chapter, followed by an exercise in applying these skills to
some slightly longer arguments.
Summary: Using the skills of evaluation
1 Find the conclusion.
2 Find the reasons and any unstated assumptions.
3 Consider how far you can go in assessing the truth of the reasons and the
unstated assumptions. Think about how you would seek further information to
enable you to assess the truth of reasons.
4 Do you have any knowledge which strengthens or weakens the argument?
(Remember to subject your own ‘knowledge’ to the same standards of scrutiny
as you apply to the claims made by others!)
5 Does the passage contain any explanations? If so, are they plausible, and are
they the only plausible explanations of what is being explained?
6 If you believe that the conclusion is not well supported by the reasons and
assumptions, can you state the way in which the move from reasons to
conclusion is flawed?