Monday, 4 August 2014
John Venn, (4 August 1834 – 4 April 1923) was an English logician and philosopher. He is famous for introducing the Venn diagram, which is used in many fields, including set theory, probability, logic, statistics, and computer science. He was born on 4 August 1834 in Kingston Upon Hull, Yorkshire to Martha Sykes and Rev. Henry Venn, who was the rector of the parish of Drypool. His mother died when he was three years old. Venn was descended from a long line of church evangelicals, including his grandfather John Venn. He would follow his family lineage and become an Anglican priest, ordained in 1859, serving first at the church in Cheshunt, Hertfordshire, and later in Mortlake, Surrey.
He was educated by private tutors until 1853 when he went to Gonville and Caius College, Cambridge. In 1857, he obtained his degree in mathematics and became a fellow. In 1862, he returned to Cambridge University as a lecturer in moral science, studying and teaching logic and probability theory. In 1868, he married Susanna Carnegie Edmonstone with whom he had one son, John Archibald Venn. In 1883, he resigned from the clergy having concluded that Anglicanism was incompatible with his philosophical beliefs. In that same year, Venn was elected a Fellow of the Royal Society and was awarded a Sc.D. by Cambridge. He died on 4 April 1923.
A Venn diagram or set diagram is a diagram that shows all possible logical relations between a finite collection of sets. They are used to teach elementary set theory, as well as illustrate simple set relationships in probability, logic, statistics, linguistics and computer science. Venn diagrams were introduced in 1880 in a paper entitled On the Diagrammatic and Mechanical Representation of Propositions and Reasonings in the "Philosophical Magazine and Journal of Science", about the different ways to represent propositions by diagrams.
The use of these types of diagrams in formal logic, according to Ruskey and M. Weston, is "not an easy history to trace, but it is certain that the diagrams that are popularly associated with Venn, in fact, originated much earlier. They are rightly associated with Venn, however, because he comprehensively surveyed and formalized their usage, and was the first to generalize them".
Venn himself did not use the term "Venn diagram" and referred to his invention as "Eulerian Circles." For example, in the opening sentence of his 1880 article Venn writes, "Schemes of diagrammatic representation have been so familiarly introduced into logical treatises during the last century or so, that many readers, even those who have made no professional study of logic, may be supposed to be acquainted with the general nature and object of such devices. Of these schemes one only, viz. that commonly called 'Eulerian circles,' has met with any general acceptance..."
The first to use the term "Venn diagram" was Clarence Irving Lewis in 1918, in his book "A Survey of Symbolic Logic". Venn diagrams are very similar to Euler diagrams, which were invented by Leonhard Euler (1708–1783) in the 18th century. M. E. Baron has noted that Leibniz (1646–1716) in the 17th century produced similar diagrams before Euler, but much of it was unpublished. She also observes even earlier Euler-like diagrams by Ramon Lull in the 13th Century.