known to be true.
67
It may, however, reveal a conclusion of which people were
not conscious or which is not readily apparent from viewing the premises on
the surface. This can happen, for example, in complex mathematical reasoning.
Syllogisms take a number of forms. These include the following:
(1)
Propositional logic.
(2)
Logic of relations.
(3)
Predicate logic.
Propositional Logic
A common form of the syllogism based on propositional logic is known as
modus ponens. This is an abbreviation of modus ponendo ponens and means
a mode or method that affirms by affirming. It is often abbreviated to MP.
This syllogism involves whole sentences or clauses.
Modus ponens is the form taken by the syllogism for applying law to facts. As
indicated in earlier discussion, the major premise of this syllogism is a
conditional statement, which is the form of most legal rules. This syllogism
takes the following form:
Components
Relationships
Major Premise
If P occurs then Q occurs
Minor Premise
P occurs
Conclusion
Therefore Q occurs
Figure 5.1 Syllogism: Propositional Logic – Modus Ponens
Logic of Relations
A second form of syllogism expounds the relations or logic between
propositions. It is illustrated by the following syllogism, which is based on the
transitivity of stable preferences:
Components
Relationships
Major Premise
John prefers football to cricket.
Minor Premise
John prefers cricket to tennis.
Conclusion
Therefore John prefers football to tennis.
Figure 5.2 Syllogism: Logic of Relations
Predicate Logic
A third form of syllogism involves predicate logic. This labels derives from the
fact that this form of the syllogism manipulates subject and predicates. This is
the form that the alleged syllogism for interpreting law takes. This syllogism
___________________
67
As John Locke (1632-1704) said in his Essay Concerning Human Understanding
Book IV, Chapter XVII: “Syllogism does not discover ideas, or their connections.
Syllogism comes after knowledge, and then a man has little need of it”.
 |
 |
 |