Deductive and Inductive Reasoning | Logical Reasoning | NET Paper 1
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According to the Oxford Dictionary, Reasoning can be defined as “the action of thinking about something in a logical, sensible way.”
Merriam-Webster dictionary defines as “the process of thinking about something in a logical way in order to form a conclusion or judgment. Or, the ability of the mind to think and understand things in a logical way.”
We can say that reasoning is a process of using existing knowledge to draw conclusions, make predictions, or construct explanations in a logical way.
UNIT VI
– Logical Reasoning (Click below on the topic to read the study
notes)
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Deductive and Inductive Reasoning
There are two major types of reasoning, deductive and inductive. The third type of reasoning is abductive reasoning. We will discuss only the first two.
Deductive Reasoning
Deductive reasoning is an argument in which widely accepted truths are being used to prove that a conclusion is right. The truths can be the recognised rules, laws, theories, and others. In other words, deductive reasoning starts with the assertion of a general rule and proceeds from there to a guaranteed specific conclusion.
In practice, syllogism is the most basic form of deductive reasoning, where two premises that share some idea support a conclusion. It may be easier to think of syllogisms as the following theorem: If A=B and C=A, then B=C.
Deductive reasoning is meant to demonstrate that the conclusion is absolutely true based on the logic of the premises.
We will understand the deductive reasoning by comparing the following example of syllogisms:
Example A:
All musical instruments make sounds.
Airplanes make sounds.
Therefore, airplanes are musical instruments.
The example A contains two objectively true premises, but its conclusion is false. Because the airplanes and musical instruments to be totally separate entities while still having the same properties.
Example B:
All art is an imitation of nature.
Music is art.
Therefore, music is an imitation of nature.
In example B, the premises are overlapping, and this premises support and prove that a conclusive statement is definitely true.
You can more easily imagine the above arguments like this:
Inductive Reasoning
“Inductive reasoning is a method of argument in which the premises are viewed as supplying some evidence for the truth of the conclusion.”
Most of the dictionaries define inductive reasoning “as the derivation of general principles from specific observations.”
Inductive reasoning begins with observations which are specific and limited in scope and then proceeds to a generalised conclusion that is likely, but not sure, in light of accumulated evidence. You could say that inductive reasoning moves from the specific to the general.
Compare these inductive arguments:
Example A:
The cost of education has been increasing over the past several decades.
Therefore, higher taxes on the rich Indian are probably the best way to help middle class Indians.
Example B:
The past two Dabangg movies have been incredibly successful at the box office.
Therefore, the next Dabangg movie will probably be successful.
The reasoning in example A is weak while example B is strong. In example A, the two statements made are likely true on their own, but the first premise does not predict the second to be true. Since there is no obvious correlation between the two, the argument is weak.
In the example B, the premise identifies a pattern, and the conclusion provides a logical continuation of this pattern without exaggeration. Thus, the argument is strong
Evaluating and Distinguishing Two Reasoning
The followings are the differences between deductive and inductive reasoning:
| Basis for comparison | Deductive Reasoning | Inductive Reasoning |
|---|---|---|
| Approach | It follows a top down approach. | It follows a bottom-up approach. |
| Starts from | Deductive reasoning starts from Premises. | Inductive reasoning starts from the Conclusion. |
| Validity | The conclusion must be true if the premises are true. | the truth of conclusions does not guarantee by the truth of premises. |
| Usage | It is difficult to use, as we need facts which must be true. | It is fast and easy, as we need evidence instead of true facts. We often use it in our daily life. |
| Process | Theory – hypothesis – patterns – confirmation. | Observations – patterns – hypothesis – Theory. |
| Argument | Arguments may be valid or invalid. | Arguments may be weak or strong. |
| Structure | It reaches from general facts to specific facts. | It reaches from specific facts to general facts. |
| Qualitative /Quantitative | It is more precise and quantitative. | It is more general and qualitative. |
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