Deduction vs Induction vs Abduction

2017-02-03

An engineer, a physicist, and a mathematician were on a train heading north, and had just crossed the border into Scotland.

The engineer looked out of the window and said "Look! Scottish sheep are black!"

The physicist said, "No, no. Some Scottish sheep are black."

The mathematician looked irritated. "There is at least one field, containing at least one sheep, of which at least one side is black."

Who is right? That depends on whether you use deductive, inductive, or abductive reasoning.

Deduction vs Induction

Deductive reasoning is strict. It prioritizes validity and soundness. When you think deductive reasoning, think Aristotle and classical logic.

Inductive reasoning is probabalistic. It is not guaranteed to be correct.

Abductive reasoning goes one step further than inductive reasoning. It is perhaps best summarized by Sherlock Holmes:

When you have eliminated the impossible, whatever remains, however improbable, must be the truth?