Re-working Exercise Argument

Read again the passage for Exercise 5 (p. 23). Identify its conclusion, reasons and unstated
assumptions. Compare the list which you originally wrote for Exercise 5 with the unstated
assumptions which you have now identified.
Parts of an argument
1 An argument offers a reason or reasons in support of a conclusion.
2 A conclusion may
• state a supposed fact (e.g. ‘It is dangerous to drive a car after drinking
alcohol’); or
• make a recommendation (e.g. ‘You ought not to drive your car’).
3 Some arguments introduce their conclusion with the word ‘so’ or the word
‘therefore’; some arguments do not contain the words ‘so’ or ‘therefore’.
4 A conclusion does not have to be the last statement in the argument.
Conclusions can appear anywhere in an argument.
5 An argument can have unstated assumptions, that is, items of information, or
ideas, which are not explicitly stated in the argument, but upon which the
argument relies in order to draw its conclusion.
6 Arguments can have many different structures, for example:
• one reason supporting a conclusion;
• two or more reasons which, taken together, support the conclusion;
• two or more reasons, each of which independently supports the conclusion;
• a reason, or reasons, which support an intermediate conclusion, which is
then used, either on its own or with other reasons, to support a main
conclusion.

Once we understand both the explicit and the implicit reasoning in a passage, we are in a
position to assess whether the reasoning is good. There are two questions involved in this
assessment:
• Are the reasons (and any unstated assumptions) true?
• Does the main conclusion (and does any intermediate conclusion) follow from the
reasons given for it?
The answer to both of these questions must be ‘yes’ in order for an argument to be a good
argument. Let us illustrate this with some simple examples. Here is the first one:
Everyone who exercises regularly in the gym has well-developed muscles. So if Mel
doesn’t have well-developed muscles, it can’t be true that she’s exercising regularly in
the gym.
In this argument, if the reason is false – that is, if it isn’t true that everyone who exercises
regularly in the gym has well-developed muscles – then the argument cannot establish that
someone without well-developed muscles does not exercise regularly in the gym. So it is
clear that we need to know whether the reason is true in order to know whether we should
accept the conclusion. If the reason were true, then, in this example, we would have a good
argument, since the reason supports the conclusion.
By contrast, in our second example the reason does not support the conclusion:
Everyone who exercises regularly in the gym has well-developed muscles. So if Mel
has well-developed muscles, she must be exercising regularly in the gym.
Here, even if the reason is true, the conclusion is not established, since the reason establishes
only that all those who exercise regularly in the gym have well-developed muscles,
and not that no-one else has well-developed muscles. This example illustrates that our
second question – as to whether the conclusion follows from the reasons given for it – is
also crucial to any assessment of an argument.