Reasoning and General Intelligence – Syllogism
Syllogism is a Greek word that does mean ‘inference’ or ‘deduction’. The problems of syllogism are based on two parts:
- Proposition / Propositions
- Conclusion / Conclusions drawn from given propositions
WHAT IS A PROPOSITION?
Just consider the sentences given below:
All the sentences mentioned above give a relation between subject and predicate. Here, it is clear from the sentences that a subject is the part of a sentence something is said about, while a predicate is the term in a sentence which is related to the subject.
Now, let us define the proposition:
A proposition is a sentence that makes a statement giving a relation between two terms. It has three parts:
(a) the subject
(b) the predicate
(c) the relation between subject and predicate
WHAT IS A CATEGORICAL PROPOSITION?
Let us see the sentences given below:
“All M are P”
“No M are P”
“Some M are P”
“Some M are not P” .
What we notice in all above-Mentioned sentences that they are condition free. These type of sentences are called Categorical Propositions. In other words a categorical Propositions has no condition attached with it and it makes direct assertion. It is different from non-categorical proposition which is in the format “If M then P”
Types of space categorical proposition:
It can be understood by the diagram given below:
Therefore, it is clear, that universal propositions either completely include the subject (A type) or completely exclude it (E type). On the other hand, particular propositions either only partly include the subject (1 type) or only partly exclude the subject (O type). Now we can summarise the four types of propositions to be used while solving the problems of syllogism:
EXAMPLE:1. Every girl is beautiful.
[All girts are beautiful.]
Each of them is healthy.
[All (of them) are healthy.]
Any one could kill the lion.
[All can kill the lion.]
Further, let us see the sentences given below:
Thus, a positive sentence with a particular person as its subject is A type. Also, a sentence in the following format is A type:
“All girls except Reeta are healthy.”
- E type: Apart from ‘no’ this type of propositions starts from ‘no one’, ‘none’, ‘not a single’ etc.