Deductive Reasoning and Inductive Reasoning for GMAT Critical Reasoning

‘Reason is the involuntary juxtaposition of thoughts to make up valid arguments.’ This reason or reasoning acts as our daily driver in making all our decisions. The stronger the reasoning the better the judgments.  An MBA graduate/Future Manager is supposed to make the best decisions for a company and hence he should be very strong at reason/logic. This is the reason that GMAT has a Critical Reasoning section.

Often test takers get confused between Inductive and Deductive reasoning, which are the branches of reasoning. Let’s take a closer look at these to evade ambiguity.

Deductive Reasoning, as the name suggests deduces something with a given premise or previously known fact. For example, if A is B and C is B then we can infer that A is C, i.e. The example taken above represents a classic case of ‘Syllogism’.

Let’s consider another example, all men are humans, Ravi is a man. Syllogism states that, from these statements, we can infer that Ravi is a human.

If you observe the pattern carefully in both the examples, we have reached to the final judgment only after looking at all the statements or premises, i.e., we have followed a top-down approach. If we consider Humans as a main class and men are a subclass, then a member of one subclass is also a member of the main class.

The figure below shows the diagrammatic representation of the example.

 

The conclusions drawn are said to be absolutely true, only when the premises and supporting statements are absolutely true i.e., A valid conclusion can be drawn only when the premises are considered true. If the facts are not correct, like for e.g. All aged men are bald, Ravi is bald. Hence Ravi is aged is a logically true statement, but an invalid deduction. This is because the considered fact that All aged men are bald is not an absolutely true statement.

Inductive reasoning, on the other hand, is a more bottom-up approach for knowing if the statement is logical. It makes a very generalized statement from the specific data. Even if the statements or the premises are all true there can be a possibility of the inferred statement (Conclusion) to be false. Let’s consider an example to understand more about inductive reasoning.

E.g. Ravi and Hemanth are both athletes. Both Ravi and Hemanth are tall. Therefore, all the athletes are tall. So, the induced or obtained statement that ‘All the Athletes are tall’ is taken from more specific statements considering Ravi and Hemanth which is false. Inductive reasoning is more open-ended on which theories can be built upon.

To sum up,

Deductive Reasoning

Inductive Reasoning

Valid conclusions can only be drawn when the arguments are absolutely true.

Strong conclusions can be drawn only when there are strong arguments supporting.   

If the premises are true, the concluded statement has to be true.

There is a chance of the conclusion to be false or invalid even if the arguments are true.

Top-down approach.

Bottom-up approach.

There is no strengthening of the conclusion and there is only a valid or an invalid conclusion.

Stronger arguments increase the probability of the conclusions being true.

As a manager of a company, one needs to have a bit of both Inductive and Deductive reasoning for a proper understanding of trends for drawing cogent conclusions.


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