Syllogism - Practice Questions & MCQ

Syllogism has been defined as “A form of reasoning in which a conclusion is drawn from two given or assumed propositions”. It is deductive reasoning rather than inductive reasoning. 

Let us begin by taking an example: All girls love to dress up.

There are two set here, (a) that of girls and (b) that of those who love to dress up. Note that in this case girls are a part of a bigger set of those who love to dress up. The concept becomes clearer with the help of Venn diagrams.

If the statement had been: Some girls love to dress up, it would mean that a part of the bigger set of girls would love to dress up. The diagrammatical representation would have been like:

In this diagram, the shaded area represents girls who love to dress up.

Now, if we have a statement like: Only girls love to dress up, it means that no one else can love to dress up. However, it does not mean that all girls love to dress up. The statement can be diagrammatically represented as:

Let us now move on to situations where there are two statements instead of one. Statements like: All boys love to play football, all girls love to play football. The diagrammatic representation of this will be:

As shown in the Venn diagram, you will see that boys and girls are parts or elements of a larger set of those who love to play football.' And also that boys and girls are two separate sets. As shown in the Venn diagram, you will see that boys and girls are parts or elements of a larger set of 'those who love to play football'. And, also that boys and girls are two separate sets.

Had the statement been, some boys love to dress up and some girls love to dress up, but no boy is girl and vice versa, it would have been represented as:

Let us now find out whether a third statement can be drawn or concluded from two given statements. All girls love to dress up. Some boys are girls. Let us again take the help of Venn diagrams to represented these.

Tips and Tricks to solve syllogism – questions:

1. Always represent the sentences diagrammatically with the use of Venn diagrams. This will help you be accurate and will save time once you are comfortable using this way to solve questions.
2. Commonly known facts have to be disregarded. So, even if the premise says all blue is red, the conclusion must be derived from the given information.
3. Do not assume any prior knowledge. The conclusion in a syllogism must be derived from the premises given, and not from any prior knowledge on the subject.
4. The conclusion must give some new information based on the two premises, and not simply reiterate the given facts.

5. One syllogism question can test the relationship among three elements only. This will help you in eliminating options and marking the right answers quickly.

6. Use initials to represented by H and C respectively. If there are two elements eg. hat and hair and comb, these can be represented by H and C respectively. If there are two elements eg. 'hat' and 'hair' avoid using a single alphabet or represent both. Instead use the abbreviation 'ht' for hat and 'hr' for 'hair' to avoid confusion while drawing the diagrams.