Thinking Skills: Critical Thinking and Problem Solving

34 Unit 2 Critical thinking: the basics

There are three possible candidates for the

conclusion of [2], if there is one. So, applying

the test, we have these possibilities:

[2a] Completed tax forms and payments must

be received by 31 July. Late payment

may result in a fine not exceeding $100.

Therefore your payment did not reach the

tax office until 12 August.

[2b] Late payment may result in a fine not

exceeding $100. Your payment did not

reach the tax office until 12 August. So

completed tax forms and payments

must be received by 31 July.

[2c] Completed tax forms and payments

must be received by 31 July. Your

payment did not reach the tax office

until 12 August. Therefore late payment

may result in a fine not exceeding $100.

In each rearrangement the attempt to use an

argument indicator sounds unnatural, which

indicates that none of the sentences is the kind

of claim that could follow from the others in

the way that a conclusion follows from

reasons.

Commentary

[3] is an argument. The conclusion, which is

at the end, is a recommendation. This also is a

useful clue: recommendations are often

accompanied by reasons. Here there are two:

the time of the train’s departure and the

possibility of a 40-minute journey to the

station. If they are both true, then clearly they

justify the conclusion.

[4] is also an argument. The conclusion is a

prediction that the police will (definitely)

suspect Raisa, firstly because she is the only

key-holder, and secondly because she was

alone in the building. The argument is

perhaps not quite as solid as [3]. Do police

always treat people as suspects in these

circumstances? The words ‘bound to.. .’ make

the conclusion a very strong claim. Even if

both premises are true, there may be other

Using the ‘therefore/so’ test, and the

definition of an argument as reasons and a

conclusion, decide which of the following

could be interpreted as arguments.

For those that are arguments, identify the

conclusion and note what kind of claim it is.

Lastly, discuss how well supported the

conclusion is, given the reasons.

[3] The Tokyo train leaves at 4.24. It

can take up to 40 minutes to get to

the station if the traffic is bad. We

should leave for the station by 3.40.

[4] Raisa is the only person with a key

to the safe. The police are bound to

treat her as a suspect. The money

Activity

went missing when she was in the

building on her own.

[5] You are likely to get a fine.

Completed tax forms and

payments must be received by 31

July and people who miss the

deadline are usually fined $100.

Your payment did not reach the

tax office until 12 August.

[6] From the 15th century European

sailors reached the lands of the east

by sailing west. Those who sailed

on and survived eventually arrived

back in Europe. When they

claimed they had sailed around the

world, few people believed them.

[7] There are only three possible causes

of the leak in your system: the pump

could be worn, a hose could be split

or one of the connections could be

loose. I’ve checked the hoses and

tightened all the connections, but

the machine still leaks.