Thinking Skills: Critical Thinking and Problem Solving

2.5 Analysing arguments 41

R3 The news is all round the college.

R4 Rajinder spread a story that I told him

in confidence.

C Rajinder cannot be trusted to keep

a secret.

The first three reasons depend on each other.

Obviously, if I had told several people, or if

others had known besides Rajinder, it might

not have been Rajinder who was to blame; and

if the news hadn’t spread there would be no

reason to suggest Rajinder had told anyone the

secret. R4, on the other hand, does not have to

be true for the conclusion to follow from the

other three. Therefore, although R4 adds

strength to the argument, it is separate from

the other reasons: an additional reason for

inferring that Rajinder cannot be trusted.

As a diagram:

R1 & R2 & R3

R4 C

Don’t worry if you have structured the

sentences a little differently. For example,

some people might prefer to treat R4 as two

reasons: Rajinder spread the story; and R5, I

told it to him in confidence. These two reasons

would of course be dependent on each other,

so the alternative analysis would be:

R1 & R2 & R3

R4 & R5 C

You will find, as you work on more complex

arguments, that there can be some differences

in the way an argument is analysed. That is

Note that the first part-sentence, ‘Short-
range flights may have become cheap’, is not a
reason. In fact it is not part of the argument at
all. The fact that flying may be cheaper would,
if anything, be a reason for choosing to fly, so
obviously it does not support the conclusion.
What it does is show why an argument is
needed. The author is saying: ‘OK, there may
be a financial reason for going by air, but look
at these other reasons for travelling by train.’
In other words, this opening clause puts the
whole argument into the context of a
potential debate: ‘Which is better: plane or
train?’

Mixed arguments
In arguments with more than two premises
there may be some that function
independently, and others that combine forces.

Try rewriting the following argument in

standard form, and explaining its structure in

words or by means of a diagram:

[3] Rajinder cannot be trusted to keep a

secret. He was the only person apart

from me who knew about Jed and

Jill getting engaged. I haven’t said a

word to anyone, yet now the news is

all round the college. And he spread

another story about Jill that I told

him in confidence.

Activity

Commentary
Once again the first sentence is the
conclusion, but this time it is supported by
four or five reasons (depending on how you
choose to analyse them).

R1 Rajinder was the only person apart from

me who knew about Jed and Jill getting

engaged.

R2 I haven’t told anyone.