166 ANSWERS, DISCUSSION, AND FURTHER ADVICE
and what we leave for the audience to accept or reject on their own. (See chapter
9.)
Chapter 6
Exercise 6.1
For conclusion a, one reason might be 'I want to improve my reasoning skills'. To
unpack this reason requires that you consider why reading a book on critical
thinking would help you to do this. In doing so, you address each of the issues
raised by the conclusion. For example (in the form 2+3+4 —> 1):
- I am reading a book on reasoning.
- I want to improve my reasoning skills.
- I cannot improve my reasoning skills without knowing more about
reasoning. - A book is an excellent source of knowledge about reasoning.
For conclusion b, an initial reason might be that 'thinking better stops you from
being tricked by clever advertising'. See how many different issues are involved that
are quite distinct from the conclusion? Each must be covered in some way in the
premises, for example (in the form 2+3+4+5 —> 1): - There are considerable benefits to be gained from studying how to
think better. - I do not want to be tricked by clever advertising.
- Clever advertising works by tricking you into buying products.
- Thinking clearly stops you being tricked by clever advertising.
- Studying how to think better does enable you to think clearly.
Exercise 6.2
a The premise 'there were many people waiting at the station' is irrelevant.
While trains crash for a variety of reasons (human error, sabotage, faulty
machinery, and so on), the number of people waiting at a station is rarely, if
ever, a cause of the crash. Even if the claim is true, it adds no greater
explanation to why the train crashed and thus is irrelevant.
b There are no irrelevant premises here. The second premise, concerning
competition, might seem to be irrelevant (given that the conclusion is about
privatisation); however, the first premise, with its connection between com-
petition and privatisation, makes it relevant.
c The premise 'politicians get too many benefits' is irrelevant (since there are no
further premises to make it relevant to the conclusion). Whether or not it is
true does nothing to make the conclusion more likely to be accepted. Now,
we may well wonder if there is another irrelevant premise. However, the