formal logic

American  

noun

1. the branch of logic concerned exclusively with the principles of deductive reasoning and with the form rather than the content of propositions.

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formal logic British  

noun

1. Also called: symbolic logic.  the study of systems of deductive argument in which symbols are used to represent precisely defined categories of expressions Compare philosophical logic

2. a specific formal system that can be interpreted as representing a fragment of natural argument

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Etymology

Origin of formal logic

First recorded in 1855–60

Example Sentences

Their method, which is based on the formal logic used by mathematicians and philosophers, captures the choices faced by a hacker who has access to the mobile phone and the PIN.

From Science Daily • Jan. 22, 2024

Pinker’s main focus is the sort of conscious, sequential reasoning that can track the steps in a geometric proof or an argument in formal logic.

From Washington Post • Oct. 7, 2021

Without even having to dip into formal logic, the long list of informal fallacies and extensive practice identifying them in real world discourse prepared me to be a discriminating adult.

From Slate • Sep. 3, 2015

This belief violates both common sense and formal logic.

From Salon • May 11, 2013

In formal logic and in mathematics, proof is something absolute.

From "Words Like Loaded Pistols" by Sam Leith