CAT Logical Reasoning: Format, Syllabus and types of Problem

Logical Reasoning

Logical Reasoning is our guide to good decisions. It is also a guide to sorting out truth from falsehood.

Like every subject, Logic has its own vocabulary and it is important that you understand the meanings of some important words/terms on which problems are usually framed in the Common Admission Test. Once you have become familiar with the vocabulary of Logic, it will be imperative that you also understand some rules/principles on which questions can be solved.

Some of the important types and styles of problems in logic are:

a. Problems based on ‘Propositions and their Implications’

These problems typically have a proposition followed by either a deductive or an inductive argument. An argument has a minimum of two statements — a premise and a conclusion, in any order.It may also have more than one premise (statement) and more than one conclusion. The information in the premise(s) either makes the conclusion weak or makes it strong. The examinee is usually required to:

i. identify the position of the premise(s) vis-à-vis the conclusion, that is, is the premise weakening or strengthening the conclusion

ii. identify if the conclusion drawn based on the premise(s) is correct or incorrect

iii. identify if only one conclusion follows, either conclusion follows, or neither conclusion follows, or both the conclusions follow (assuming the problem has two premises and two conclusions)

iv. identify an option in which the third statement is implied by the first two statements; this type of question is called a — Syllogism

v. identify the correct ordered pair where the first statement implies the second statement and both these statements are logically consistent with the main proposition (assuming, each question has a main proposition followed by four statements A, B, C, D)

vi. identify the set in which the statements are most logically related (assuming, each question has six statements and there are four options listed as —sets of combinations of three statements ABD, ECF, ABF, BCE etc.)

vii. identify the option where the third segment can be logically deduced from the preceding two (assuming, each question has a set of four statements and each of these statements has three segment, for example:

A.   Tedd is beautiful;
      Robo is beautiful too;
      Ted is Robo.
B.   Some apples are guavas;
      Some guavas are oranges;
      Oranges are apples.
C.  Tedd is beautiful;
     Robo is beautiful too;
     Tedd may be Robo.
D.  Apples are guavas;
     Guavas are oranges;
     Oranges are grapes.

(a) Only C    

(b) Only A    

(c) A and C    

(d) Only B

The answer to the above question is option (c)
The above is in no way an exhaustive list of problems on logic, but it gives a fair view of the types and styles of questions that one may face.