Today marks the 180th birthday of the English philosopher and mathematician John Venn, who is most famous for unleashing the eponymous Venn diagram onto the world.
While Venn was a pretty cool guy, truth be told, his "in-Venn-tion" is not that original. Venn diagrams are merely a subcategory of Euler diagrams, which predate Venn by a century.
Indeed, Venn himself never presumed to name the diagrams after himself, and called his figures Eulerian Circles. Furthermore, a case could be made that the diagrams predate Euler by several centuries as well. For example, the 13th century mystic Ramon Llull experimented with diagrams that explored interconnected concepts, such as the "Prima Figura" pictured below.
Regardless of who has the bragging rights, the aesthetic and educational value of Venn's specific riff on these established diagrams caught on big in time, so much so that genuine Euler diagrams are commonly mislabeled as Venn diagrams.
The big difference between the two is that the circles on Venn diagrams must intersect, demonstrating the common features of every demonstrated set. Euler diagrams are also represented with circles, but not every set has to intersect with the others. The figure below, for example, is a Euler circle rather than Venn diagrams.
But despite their differences, both Euler and Venn diagrams were developed for the same purpose: to help visualize the interrelationships between "propositions," one of the most slippery words in all of philosophy (and that is a competitive category).
The use of the diagram was further popularized by its induction into the "new math" movement of the 1960s. This pedagogical pivot was catalyzed by the Sputnik crisis, and was designed to get grade school kids acquainted with complex mathematical principles—like set theory—as early as possible, so they could invent fancy spaceships and beefed-up missiles like good little patriots.
But like the very concepts they aim to illustrate, Venn diagrams could not remain boxed into one constrictive circle. Educators of every stripe began to co-opt the figures for their own lesson plans, which is why you probably had to create them in pretty much every class at school.
Need to learn the commonalities of narrative points-of-view? Venn diagram.
Need to classify biological taxa? Venn diagram.
Want to point out random similarities between any two seemingly unrelated subjects? Venn diagram.
Finally, need to illustrate some of Motherboard's favorite topics to report on? Boom: Venn diagram.
In one of those bizarre twists that history loves to serve up, the launch of Sputnik directly enabled the Venn diagram to become one of the most widely recognized memes of all time. So happy birthday John Venn, quasi-inventor of the Venn diagram. And may all your intersecting circles be harmonious.