Pho­to by Tamiko Thiel via Wiki­me­dia Com­mons

How can we know whether a claim some­one makes is sci­en­tif­ic or not? The ques­tion is of the utmost con­se­quence, as we are sur­round­ed on all sides by claims that sound cred­i­ble, that use the lan­guage of science—and often do so in attempts to refute sci­en­tif­ic con­sen­sus. As we’ve seen in the case of the anti-vac­cine cru­sade, falling vic­tim to pseu­do­sci­en­tif­ic argu­ments can have dire effects. So how can ordi­nary peo­ple, ordi­nary par­ents, and ordi­nary cit­i­zens eval­u­ate such argu­ments?

The prob­lem of demar­ca­tion, or what is and what is not sci­ence, has occu­pied philoso­phers for some time, and the most famous answer comes from philoso­pher of sci­ence Karl Pop­per, who pro­posed his the­o­ry of “fal­si­fi­a­bil­i­ty” in 1963. Accord­ing to Pop­per, an idea is sci­en­tif­ic if it can con­ceiv­ably be proven wrong. Although Popper’s strict def­i­n­i­tion of sci­ence has had its uses over the years, it has also come in for its share of crit­i­cism, since so much accept­ed sci­ence was fal­si­fied in its day (Newton’s grav­i­ta­tion­al the­o­ry, Bohr’s the­o­ry of the atom), and so much cur­rent the­o­ret­i­cal sci­ence can­not be fal­si­fied (string the­o­ry, for exam­ple). What­ev­er the case, the prob­lem for lay peo­ple remains. If a sci­en­tif­ic the­o­ry is beyond our com­pre­hen­sion, it’s unlike­ly we’ll be able to see how it might be dis­proven.

Physi­cist and sci­ence com­mu­ni­ca­tor Richard Feyn­man came up with anoth­er cri­te­ri­on, one that applies direct­ly to the non-sci­en­tist like­ly to be bam­boo­zled by fan­cy ter­mi­nol­o­gy that sounds sci­en­tif­ic. Simon Oxen­ham at Big Think points to the exam­ple of Deep­ak Chopra, who is “infa­mous for mak­ing pro­found sound­ing yet entire­ly mean­ing­less state­ments by abus­ing sci­en­tif­ic lan­guage.” (What Daniel Den­nett called “deep­i­ties.”) As a balm against such state­ments, Oxen­ham refers us to a speech Feyn­man gave in 1966 to a meet­ing of the Nation­al Sci­ence Teach­ers Asso­ci­a­tion. Rather than ask­ing lay peo­ple to con­front sci­en­tif­ic-sound­ing claims on their own terms, Feyn­man would have us trans­late them into ordi­nary lan­guage, there­by assur­ing that what the claim asserts is a log­i­cal con­cept, rather than just a col­lec­tion of jar­gon.

The exam­ple Feyn­man gives comes from the most rudi­men­ta­ry source, a “first grade sci­ence text­book” which “begins in an unfor­tu­nate man­ner to teach sci­ence”: it shows its stu­dent a pic­ture of a “wind­able toy dog,” then a pic­ture of a real dog, then a motor­bike. In each case the stu­dent is asked “What makes it move?” The answer, Feyn­man tells us “was in the teacher’s edi­tion of the book… ‘ener­gy makes it move.’” Few stu­dents would have intu­it­ed such an abstract con­cept, unless they had pre­vi­ous­ly learned the word, which is all the les­son teach­es them. The answer, Feyn­man points out, might as well have been “’God makes it move,’ or ‘Spir­it makes it move,’ or, ‘Mov­abil­i­ty makes it move.’”

Instead, a good sci­ence les­son “should think about what an ordi­nary human being would answer.” Engag­ing with the con­cept of ener­gy in ordi­nary lan­guage enables the stu­dent to explain it, and this, Feyn­man says, con­sti­tutes a test for “whether you have taught an idea or you have only taught a def­i­n­i­tion. Test it this way”:

With­out using the new word which you have just learned, try to rephrase what you have just learned in your own lan­guage. With­out using the word “ener­gy,” tell me what you know now about the dog’s motion.

Feynman’s insis­tence on ordi­nary lan­guage recalls the state­ment attrib­uted to Ein­stein about not real­ly under­stand­ing some­thing unless you can explain it to your grand­moth­er. The method, Feyn­man says, guards against learn­ing “a mys­tic for­mu­la for answer­ing ques­tions,” and Oxen­ham describes it as “a valu­able way of test­ing our­selves on whether we have real­ly learned some­thing, or whether we just think we have learned some­thing.”

It is equal­ly use­ful for test­ing the claims of oth­ers. If some­one can­not explain some­thing in plain Eng­lish, then we should ques­tion whether they real­ly do them­selves under­stand what they pro­fess…. In the words of Feyn­man, “It is pos­si­ble to fol­low form and call it sci­ence, but that is pseu­do­science.”

Does Feynman’s ordi­nary lan­guage test solve the demar­ca­tion prob­lem? No, but if we use it as a guide when con­front­ed with plau­si­ble-sound­ing claims couched in sci­en­tif­ic-sound­ing ver­biage, it can help us either get clar­i­ty or suss out total non­sense. And if any­one would know how sci­en­tists can explain com­pli­cat­ed ideas in plain­ly acces­si­ble ways, Feyn­man would.

Note: An ear­li­er ver­sion of this post appeared on our site in 2016.

Relat­ed Con­tent:

Carl Sagan’s “Baloney Detec­tion Kit”: A Toolk­it That Can Help You Sci­en­tif­i­cal­ly Sep­a­rate Sense from Non­sense

The Life & Work of Richard Feyn­man Explored in a Three-Part Freako­nom­ics Radio Minis­eries

How to Spot Bull­shit: A Man­u­al by Prince­ton Philoso­pher Har­ry Frank­furt (RIP)

Richard Feyn­man Presents Quan­tum Elec­tro­dy­nam­ics for the Non­Sci­en­tist

Josh Jones is a writer and musi­cian based in Durham, NC. Fol­low him at @jdmagness