What is Every Schoolboy Knows?

You would be amazed what every schoolboy knows. Anxious to secure acquiescence in their controversial claims, disputants solemnly assure their audiences that every schoolboy knows the

truth of what they are saying. The audience, not wishing to be ignorant of matters so widely understood by children, are supposed to keep silent about their doubts. Thus complex and dubious assertions are passed off unquestioned.

Every schoolboy knows that the rate of gene loss from a closed reproductive system is expressed by a simple and well-known formula.

(Indeed, this is the main topic of conversation over catapults and conkers.)


The tactic is fallacious. Its basic purpose is to appeal beyond the evidence to secure acceptance. The audience is invited to assent not from conviction but out of shame and fear of being thought less knowledgeable than a mere child. The merits of the point are meanwhile overlooked.

So widely used is the tactic that the hapless youth is now encumbered with several encyclopaedias of knowledge. There is scarcely anything which he does not know.


As my learned colleague is doubtless aware, every schoolboy knows that it was Rex v. Swanson which established in 1749 the precedents governing the use of coaching horns on the public highway.

(And you can be sure that the same gifted, if youthful, legal scholar is also aware of the judgment in Higgins v. Matthews 1807.)


The aforementioned schoolboy has an intuitive grasp of the obvious, and has been widely praised for this ability:


Why, it is obvious even to a mere child that interstellar dust clouds would long ago have been excited to incandescence and be emitting black-body radiation were it not for the expansion of the universe.

(It is not quite clear whether the mere child finds this obvious even before he becomes every schoolboy, or whether he picks it up after a few lessons.)

The fallacy is a special case of the more general fallacy of false advertisement, which consists of advance praising of your own views. Since you precede them by the information that they are known to every schoolboy and obvious to a mere child, you are scattering roses in their path. The fallacy may be perpetrated no less effectively by opening with ‘Obviously’ contentions which are by no means obvious.

We hold these truths to be self-evident.

(So anyone who doesn’t agree must be really stupid.)


To use the fallacy effectively, you should never enter an argument without taking half the kindergarten class along for the walk. As well as the mere child and every schoolboy, you will need even a half-wit, albeit a very knowledgeable one. Every beginner should be in your posse to instruct the experts, and for sheer range of vision you will need everyone.


‘Everyone can see that…’

(Even where no one else but you has such sharp eyes.)


When putting across a really controversial point, you might as well send the whole team into action:

Every schoolboy knows the description of the visitors in Ezekiel; and a half-wit realizes that ancient disasters were caused by cosmic disturbances. A mere child could work out that extraterrestrial forces involved, so it is obvious to everyone that Earth has been under attack for centuries. Now as even beginners to the study of UFOs know only well…

(By this time your schoolchildren and half-wits should have cleared everyone else off the field.)


Do beware of actual schoolboys though. If there is one in your audience, the smart alec is quite likely to step forward and contradict you with the facts. Some of them are too good.


The above article is from the book How To Win Every Argument by Madsen Pirie. The article is only for educational and informative purposes to explain and understand formal logic and logical fallacies. It is a great book, definitely worth a read!