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What does it mean to “trust science”?

Truth: why science doesn’t care about your opinion

Yves Laszlo, Professor of Mathematics at Université Paris-Saclay
On June 23rd, 2021 |
5 min reading time
Yves Lazlo
Yves Laszlo
Professor of Mathematics at Université Paris-Saclay
Key takeaways
  • The recent rise in mistrust of science questions scientific facts and risks hindering its progress.
  • It is characterised by a tendency to favour individual opinions, which are by definition subjective, rather than to the facts, which are objective.
  • However, the universality of facts, and consequently the reproducibility of experimental results, should help to reduce scepticism about science as an enterprise that aims to reach the truth.
  • Contrary to mistrust, doubt within the scientific community is beneficial to science because it allows us to refine knowledge by challenging that which we consider to be ‘true’.

The last few decades could be seen as a gold­en age for sci­ence. Indeed, it has the capac­i­ty to both describe and pre­dict the behav­iour of our world, allow­ing us to estab­lish ways to apply that under­stand­ing to our lives: the genom­ic rev­o­lu­tion, the quan­tum rev­o­lu­tion, the reign of the Inter­net, and the tri­umph of rel­a­tiv­i­ty, to name a few. As sci­ence pro­vides descrip­tion and mod­els, expec­ta­tions grow for tech­nol­o­gy to pro­vide the tools to tack­le the big glob­al chal­lenges we are facing.

Although, recent past has also proven us to be in a time of post-truth, where ‘alter­na­tive facts’ or fake news run ram­pant and mis­trust in sci­ence is rife. Often, the fin­ger is point­ed at the spread of social media as the cul­prit, but it must be said that it is not the only one.

Mis­in­for­ma­tion encour­ages a cul­ture of sus­pi­cion with regards to sci­en­tif­ic facts. How­ev­er, sim­ply point­ing it out as such is not the rem­e­dy to reverse mis­trust in sci­ence; con­fi­dence in sci­ence could be inter­pret­ed as a sub­jec­tive ‘opin­ion’ and, as such, could dri­ve the oppo­site effect fur­ther rein­forc­ing doubt in a ‘denier’. 

A sci­en­tif­ic fact dif­fers from opin­ion in that it must be described with­in a well-defined perimeter.

There­fore, this conun­drum begs the ques­tion of what can be done. Are we able to re-estab­lish trust in the sci­en­tif­ic method and the pur­suit of knowl­edge? Or are we doomed to fight against dis­be­lief and unrea­son­able doubt that goes beyond the required lev­el of crit­i­cal think­ing that is nec­es­sary for us to progress in our under­stand­ing of the universe? 

Per­haps a good place to start is to con­sid­er the dif­fer­ence in nor­ma­tive sta­tus between ‘sci­en­tif­ic fact’ and ‘opin­ion’. Apart from say­ing that sci­ence is what sci­en­tists are doing, which is part of its def­i­n­i­tion, sci­en­tif­ic facts also have a well-defined perime­ter of valid­i­ty and are uni­ver­sal in this set­up. This means they can be used to make pre­dic­tions of which the con­fi­dence of such is based on replic­a­ble tests or exper­i­ments defined a pri­ori and val­i­dat­ed a pos­te­ri­ori. Last but not least, the hypoth­e­sis test­ed by exper­i­ments are objec­tive­ly refutable – prob­a­bly one of the main dif­fer­ences between ‘sci­en­tif­ic fact’ with ‘opin­ion’.

Facts have well-defined boundaries

A sci­en­tif­ic fact dif­fers from opin­ion in that it must be described with­in a well-defined perime­ter; one can­not talk about things “just like that” with­out a min­i­mum of pre­ci­sion. For exam­ple, we can debate whether the sofa should go against the back wall or the left one. You may want it to go over there, because there is more nat­ur­al light in that spot. Where­as I may want it to go over here where it is most prac­ti­cal to move around. Both are valid opin­ions, but nei­ther are facts because we are both mak­ing our deci­sions based on our own (often, unde­fined) para­me­ters. More­over, the result wouldn’t be uni­ver­sal, mean­ing the results would depend on the own­er of the sofa own­er and his/her mood.

How­ev­er, if we agreed that the sofa should be placed where there is most nat­ur­al light –  which we could define by pre­scrib­ing an inten­si­ty dis­tri­b­u­tion of light at spe­cif­ic wave lengths – then we have a defined, mea­sur­able para­me­ter, which we can study in an objec­tive man­ner. As such, using dif­fer­ent meth­ods we can research the pre­cise loca­tion in the room where there is the most nat­ur­al light based on empir­i­cal mea­sures of UV rays, heat, time in the sun per 24 hours etc. Using those results we can define the perime­ter of a sci­en­tif­ic fact, math­e­mat­i­cal­ly mod­el the pre­cise, uni­ver­sal, sofa-own­er-inde­pen­dent loca­tion in the room where the most nat­ur­al light is found using the nec­es­sary ana­lyt­i­cal techniques. 

Scientific facts can be used to make predictions

Once we have defined those para­me­ters and the meth­ods used to study them, the mea­sures or exper­i­ments must be replic­a­ble. Replic­a­bil­i­ty is defined as “obtain­ing con­sis­tent results across stud­ies aimed at answer­ing the same sci­en­tif­ic ques­tion, each of which has obtained its own data1”. Hence, any­body should be able to repro­duce the same results by apply­ing the same pro­to­col to a sys­tem. In the instance of the sofa, per­haps this would not be so dif­fi­cult. When it comes to com­plex struc­tures like liv­ing sys­tems for instance, replic­a­bil­i­ty is a huge challenge. 

More­over, in order to be ‘true’, the fact must be uni­ver­sal – the same laws of grav­i­ta­tion are in place whether you are in Paris, New York or at the North Pole. In fact, they are even the same laws if you are on Earth or Mars because, whilst you may not expe­ri­ence grav­i­ty in the same way your­self, Einstein’s the­o­ry of rel­a­tiv­i­ty still applies wher­ev­er in the uni­verse you hap­pen to be.

So, tak­ing the first points into con­sid­er­a­tion, if sci­en­tif­ic facts are the same every­where and they are repro­ducible under the same con­di­tions then they can be used to make pre­dic­tions. If we know that every day the sun ris­es in the East and sets in the West, we can say with absolute cer­tain­ty that it will do so tomor­row and every day that fol­lows. And this will hap­pen regard­less of whether we believe it will: the sun does not, under any cir­cum­stances, care about our opin­ion of it. 

Theories are more often refined than refuted 

Once it is well-defined, has been test­ed repro­ducibly and can be used to pre­dict out­comes, the only thing left is to test the lim­its of the sci­en­tif­ic fact in ques­tion. In his motion the­o­ry, Isaac New­ton posit­ed that speed motion is always rel­a­tive and time is absolute, who­ev­er is com­put­ing it2. In one of his 19053 sem­i­nal papers, Ein­stein posit­ed than the light speed c in a vac­u­um is absolute – imply­ing in turn that time is rel­a­tive. This non-intrin­sic char­ac­ter of time is pre­cise­ly one way of a pos­si­ble ‘refu­ta­tion’ of the the­o­ry, but, for­tu­nate­ly, has not yet been. 

Even though Einstein’s rel­a­tiv­i­ty seems to bury New­ton­ian physics, he didn’t actu­al­ly refute his pre­de­ces­sors’ the­o­ries. Rather, he refined them. Both New­ton and Ein­stein were essen­tial­ly right: Newton’s physics is right for ‘slow’ speeds (bear­ing in mind that even a hyper­son­ic rock­et has a slow speed in this con­text!) but not for speeds close to c (the speed of light). For slow speeds, both Einstein’s and Newton’s the­o­ries coin­cide. Ein­stein sim­ply offered a more thor­ough expla­na­tion of the universe.

Anoth­er exam­ple would be genet­ics. When Mendel was study­ing hered­i­ty in pea plants, he knew that char­ac­ter­is­tics could be passed down through the gen­er­a­tions in a species. We then learnt of the exis­tence of DNA and that hered­i­ty is con­tained with­in the genes that par­ents trans­fer to their off­spring. So, for a while, sci­en­tif­ic fact had been that our genet­ic inher­i­tance was defined sole­ly by our DNA that was wired at birth. 

Even though Einstein’s rel­a­tiv­i­ty seems to bury New­ton­ian physics, he didn’t actu­al­ly refute his pre­de­ces­sors’ the­o­ries. Rather, he refined them.

More recent­ly, we dis­cov­ered epi­ge­net­ics: the exis­tence of mol­e­c­u­lar switch­es capa­ble of turn­ing genes on or off in a process that can hap­pen at any point over the lifes­pan of an organ­ism. Thus mean­ing that expe­ri­ences can influ­ence gene func­tions by mak­ing small adjust­ments to our DNA and, on top of that, these ‘acquired’ mod­i­fi­ca­tions can be trans­ferred to our off­spring through the gen­er­a­tions. Again, the role of DNA in hered­i­ty was not refut­ed; instead, it was our under­stand­ing of the big­ger pic­ture that matured.

These exam­ples show the fun­da­men­tal impor­tance of the sci­en­tif­ic ques­tion­ing dri­ven by the fruit­ful ‘col­lec­tive doubt’, oppo­site to peremp­to­ry asser­tions often sur­round­ing opin­ions or worse ‘alter­na­tive facts’.

Doubt is healthy, mistrust is not

It is this ‘col­lec­tive doubt’ that sci­en­tists share with one anoth­er, which allows that refin­ing process to hap­pen. Ques­tion­ing one anoth­er, chal­leng­ing the meth­ods used and adding new infor­ma­tion from oth­er sources helps sci­en­tif­ic facts flour­ish in a way that becomes extreme­ly dif­fi­cult to refute. Hence, rather than weak­en sci­en­tif­ic fact, sci­en­tif­ic doubt actu­al­ly serves to strength­en it. There­fore, in the end, it is actu­al­ly very rare that accept­ed sci­en­tif­ic fact is entire­ly thrown out to the trash when faced with new find­ings. Rather, sci­en­tif­ic facts tend to be refined. We rede­fine the out­lines and learn more about the para­me­ters or meth­ods used, allow­ing us to chis­el a clear­er image of the truth like that of a pix­e­lat­ed com­put­er screen, which becomes sharp­er as we add pix­els. After all, the goal of sci­ence is to per­sis­tent­ly improve the def­i­n­i­tion of the image we have of the universe.

2Philosophi­ae nat­u­ralis prin­cip­ia math­e­mat­i­ca, 1687
3Zur Elek­tro­dy­namik bewegter Kör­p­er, Annalen der Physik

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