Lesson 8: Induction and Deduction, Tuesday 12th November 2013

What is induction and deduction, and what is the difference between them?


Induction is the reasoning from the particular/specific instances to the more general principles such as, metal “A” expands when heated, and so does metal “B” and “C”. Therefore, all metals expand when heated. Another example for induction could be in history, every human I’ve read about has died, and I’ve never heard of a human who has not eventually died, therefore all humans will die. In this example, we logically proceed from every human I’ve read about (specific) to all humans will die (generalisation).

However, in inductive reasoning, no matter how extensive or thorough a person has conducted their research, they can never reach absolute certainty using inductive reasoning. This is because some kind of generalisation is always made from the observed or the non-observed.

To make inductive reasoning reliable, there are some aspects to consider such as how much research or examples ma-

Confirmation bias: we tend to believe what we wants to believe or remember what fits the pattern, and ignore or forget what goes against it.

Deduction is the complete opposite of induction, and it is the reasoning from general principles to the more specific instances such as, all metal expands when heated. “A” is a metal, and therefore “A” expanses when heated. Another example for deduction could be, all organisms have RNA. This fruit “f” is an organism, and therefore “f” has RNA. 

However these definitions of induction and deduction can be misleading for several reasons such that,