How Medieval Cathedrals Were Built Without Science, or Even Mathematics

Sci­ence and engi­neer­ing may be con­flat­ed to some degree in the pub­lic mind, but any­one who’s spent much time in an aca­d­e­m­ic depart­ment belong­ing to one or the oth­er of those branch­es of endeav­or knows how insis­tent­ly dis­tinc­tions can be drawn between them. Bill Ham­mack, a pro­fes­sor of engi­neer­ing at the Uni­ver­si­ty of Illi­nois Urbana-Cham­paign who’s been there since he was a mas­ter’s stu­dent in 1986, sure­ly has his own thoughts on the sub­ject. The video above from his pop­u­lar YouTube chan­nel Engi­neer­guy explains how cathe­drals were designed in the Mid­dle Ages, using the exam­ple of Sainte-Chapelle in Paris. Specif­i­cal­ly, it gets into how such a build­ing’s arch­es and sup­port­ing walls could have been engi­neered with­out the aid of sci­ence at all, or even the use of math­e­mat­ics.

Com­pared to today, the scope of knowl­edge human­i­ty com­mand­ed back in medieval times may have been impos­si­bly nar­row — to say noth­ing of the knowl­edge pos­sessed by any giv­en human, espe­cial­ly out­side the lit­er­ate elite. Yet what was then known proved more than suf­fi­cient to build struc­tures that still stand, and indeed impress, many cen­turies (and in some cas­es, more than a mil­len­ni­um) lat­er.

Ham­mack explains that, in the place of mak­ing cal­cu­la­tions, their builders would per­form actions. For instance, a medieval mason would have made a life-size chalk draw­ing of the arch, laid a rope along its form, and cut the rope’s length to match that of the arch. He could then use the rope to deter­mine just how thick the wall would need to be, between a fourth and a fifth of the arch’s span, with­out a num­ber ever being involved.

Ham­mack notes that the Romans, too, under­stood this nec­es­sary pro­por­tion for arch con­struc­tion. “The pro­por­tion­al rule does­n’t come from some sci­en­tif­ic analy­sis of stone and its prop­er­ties,” he says. “It comes from cen­turies of expe­ri­ence, from tri­al and error.” Such heuris­tics, or rules of thumb, con­sti­tute “an impre­cise method used as a short­cut to find a solu­tion to a prob­lem, often by nar­row­ing the range of pos­si­ble solu­tions.” They’re also employed in the engi­neer­ing method to “cause the best change in a poor­ly under­stood sit­u­a­tion using avail­able resources.” Its thor­ough­go­ing prac­ti­cal­i­ty would seem to have lit­tle to do with the dif­fer­ent sort of rig­ors that apply in sci­ence, where estab­lish­ing truth, or at least the absence of false­ness, is all. Belief in the engi­neer­ing approach to prob­lems like this does­n’t require faith in the reli­gious sense, but if you like, you can find proof of its effec­tive­ness in hous­es of wor­ship from Sainte-Chapelle to the Pan­theon to Hagia Sophia — or at least in their arch­es.

Relat­ed Con­tent:

Göbek­li Tepe: The 12,000-Year-Old Ruins That Rewrite the Sto­ry of Civ­i­liza­tion

The Cre­ation & Restora­tion of Notre-Dame Cathe­dral, Ani­mat­ed

An Ani­mat­ed Video Shows the Build­ing of a Medieval Bridge: 45 Years of Con­struc­tion in 3 Min­utes

Behold a 21st-Cen­tu­ry Medieval Cas­tle Being Built with Only Tools & Mate­ri­als from the Mid­dle Ages

How Design­ing Build­ings Upside-Down Rev­o­lu­tion­ized Archi­tec­ture, Mak­ing Pos­si­ble St. Paul’s Cathe­dral, Sagra­da Família & More

The Longest Con­struc­tion Projects in His­to­ry: Why Sagra­da Família, the Milan Duo­mo, Greek Tem­ples & Oth­er Famous Struc­tures Took Gen­er­a­tions to Com­plete

Based in Seoul, Col­in Marshall writes and broad­casts on cities, lan­guage, and cul­ture. He’s the author of the newslet­ter Books on Cities as well as the books 한국 요약 금지 (No Sum­ma­riz­ing Korea) and Kore­an Newtro. Fol­low him on the social net­work for­mer­ly known as Twit­ter at @colinmarshall.