<*biography, history of philosophy*> British logician (1834-1923).
In Symbolic Logic (1881) Venn applied the insights of Boole,
Euler, and others in developing a diagrammatic method for
testing the validity of categorical syllogisms. He also
contributed to the development of modern theories of probability
in The Logic of Chance (1867) and The Principles of Empirical or
Inductive Logic (1889).

[A Dictionary of Philosophical Terms and Names]

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<*logic, mathematics*> John Venn's modern pictorial method
of representing and evaluating the validity of
categorical syllogisms. The classes designated by the
terms of a syllogism are represented by overlapping circles,
with shading and ×s indicating, respectively, the impossibility
and existence of their common members.
Recommended Reading: Sun-Joo Shin, The Logical Status of
Diagrams (Cambridge, 1994).

[A Dictionary of Philosophical Terms and Names]

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