An Introduction to Critical Thinking and Creativity - always yours

SOME NICETIES 101
Another method that is particularly useful in argument mapping is to follow these
two guidelines: 1
• The holding hands rule: Every key term appearing in a premise of an argument
but not in the conclusion must also appear in some other premise.
• The rabbit rule: Every key term appearing in the conclusion of an argument
must also appear in at least one of the premises.
These two rules are only guidelines because they have exceptions, but they are still
very useful in formulating arguments for which the reasoning from the premises
to the conclusion is made explicit. They are particularly useful in drawing argument
maps, and looking at an example will help us better understand how they
work and their rationale. Let us return to the last argument:
Homosexuality is unnatural.
I
Homosexuality is morally wrong.
The underlined phrases show that the argument violates both the rabbit rule
and the holding hands rule. The rabbit rule is violated because the concept of
something being morally wrong appears in the conclusion, but it cannot be found
anywhere in the premises. The motivation for the rabbit rule is to ensure that different
parts of the conclusion can be traced back to the premises. In general, if
a concept is present in the conclusion, some assumption must have been made
relating to the concept in question. The aim of the rabbit rule is to make these
assumptions explicit and show how the premises lead to the specific conclusion.
Otherwise it might not be clear how the conclusion comes about. When the conclusion
suddenly introduces something that has not been mentioned before, it is
like a magic trick, producing a rabbit out of a magician's hat!
On the other hand, the word unnatural is underlined to show that the holding
hands rule has been violated. The rationale for this rule is to ensure relevance. If a
concept appears in a premise but not the conclusion, we might wonder why that
concept is mentioned at all. What work does it actually do in the argument? Is it
really necessary? By requiring that the concept appears again in another premise,
we hope to ensure that the premises are linked together ("holding hands") in a
way that reveals the role of the concept in the reasoning process. Returning to our
example, consider the following modified argument map:
1 The rules came from a set of argument-mapping tutorials fromthe Australian company Austhink.