Argument in Critical reasoning

‘Argument indicator’ words
The language of reasoning can be very complex, but there are some relatively simple
linguistic clues which can signal that reasoning is taking place. Certain characteristic words
are used to indicate that someone is presenting a conclusion, the most commonly used
being ‘therefore’ and ‘so’. For example, the argument presented in the first paragraph of
this section could be written as:
He told us he was forty-two, but he has a daughter who is at least thirty years old.
So, he must be older than he says he is.
‘Hence’ and ‘thus’ can also function in the same way as ‘so’ and ‘therefore’, though they are
less commonly used. Other words may indicate the presence of a conclusion, for example,
‘must’, ‘cannot’. In the original version above, the word ‘must’ is used to show that the
reasons offered force us to draw the conclusion. The word ‘cannot’ could function in a
similar way, since the conclusion could have been expressed as follows: ‘He cannot be as
young as he says he is’. Sometimes the word ‘should’ can signal that someone is presenting
a conclusion, because arguments often make a recommendation. This is shown in two
of the examples above; the third, which recommends appearing confident in a job interview,
and the fourth, which recommends speaking two languages to babies. All of these
‘conclusion indicator’ words have other uses in addition to their function in
arguments, so their presence in a written passage does not guarantee that an argument is
being offered. However, they are useful indicators in assessing whether a passage contains
an argument.
Recognising arguments without argument indicator words
Some passages which contain arguments have no argument indicator words. In order to
recognise them as arguments, it is necessary to consider the relationships between the
statements in the passage, to assess whether some of the statements can be taken to
support a statement expressing a conclusion. For example, the following passage can be
construed as an argument:
Knowing the dangers of smoking is not sufficient to stop people from smoking.
One-third of the population still smokes. Everyone must know that smoking causes
lung cancer and heart disease.
This passage is clearly presenting as a statistical fact that one-third of the population
smokes, and as an obvious truth that everyone must know the dangers of smoking. It is
using these reasons to support the conclusion that knowing the dangers is not sufficient to
stop smokers from smoking.
Note that the only candidate for a conclusion indicator – the word ‘must’ – appears not
in the conclusion, but in one of the reasons. Yet, we can be clear that the last sentence is
not the conclusion, because no appropriate evidence (for example, that there have been
programmes to educate the public about the dangers) is offered. Note also that in this
example, as well as in our first example, the conclusion does not appear at the end of the
passage. We need to be aware that conclusions can appear anywhere within a passage, even
though it is possible for us to ‘tidy up’ an argument by writing out the reasons first and
ending with a conclusion introduced by ‘so’ or ‘therefore’.
We have now considered two things we might look for to identify the conclusion of an
argument:
• conclusion indicator words;
• the claim for which reasons appear to be offered.
Note that if we have identified a conclusion, we have also identified the passage as an
argument or as something which is intended to be an argument. If we have identified the
conclusion by finding conclusion indicator words, then it is reasonable to regard the
author as intending to present an argument. Earlier, we introduced the term ‘argument’ as
one way in which people use language when they are attempting to persuade or convince
others of the truth of something – that is to say, when they have a particular purpose.
However, when trying to assess whether a written passage presents an argument, we are
not solely trying to guess the purpose of the author in writing the passage. We can also
attempt to interpret the way in which this piece of language functions: this is what we are
doing when we identify the conclusion by the second method, that is to say by looking
for the claim for which reasons appear to be offered. If a passage can be written out as a
series of reasons supporting a conclusion, then it can be construed as an argument, even if
the author did not quite intend it in that way.

Nevertheless, it is often useful as a first step to consider the purpose of a passage when
trying to decide whether it is an argument. If you ask yourself, ‘What is the main point
which this passage is trying to get me to accept or believe?’, you can then underline the
sentence which you think expresses the main point. The next step is to check whether the
rest of the passage contains a reason or series of reasons which support the main point. You
do not need to worry too much at this stage about whether they give conclusive support,
because you are not yet attempting to evaluate the reasoning. Consider whether they are
relevant to the main point, and whether they support it, rather than counting against it.
Do they provide the kind of evidence or reasoning which one would need to present in
order to establish the truth of the main point? If you are satisfied on these matters, then
you can take it that you have identified a conclusion of an argument, and thereby decided
that the passage is an argument. You may find it useful to tidy up the argument by writing
it out as a series of reasons, followed by your chosen conclusion, introduced by ‘so’ or
‘therefore’.
Identifying conclusions
In this section are some examples in which we put these recommendations into
practice.
The new miracle drug Amotril has caused unforeseen side effects of a devastating
nature. Careful testing of the drug prior to its marketing could have prevented the
problems caused by these side effects. Therefore, no new drugs should be released
for public consumption without a thorough study of their side effects.
(Law School Admission Test, 1981)
This argument presents its conclusion in a straightforward way, and this helps to make
it an easy passage to analyse. We first notice that the word ‘Therefore’ introduces the last
sentence, so it is obvious that the conclusion we are being led to accept is:
no new drugs should be released for public consumption without a thorough study
of their side effects.
The reason given for this is that careful testing of Amotril before it went on sale could have
prevented the problems caused by its devastating side effects. In this case, we do not need
to tidy up the argument, since it is clear what claim is being made. Moreover, the reason
gives good support for the conclusion, provided we assume that one could not find out
about a drug’s side effects without thorough study, and that it is never worth taking the
risk of offering a drug for sale unless we are as certain as we can be that it has no serious
side effects.
Here is another example:
People who diet lose weight. Falstaff cannot have dieted. He hasn’t lost weight.