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[ba-ohs-talk] Argument by rating

While rating systems do have merit, and we all use them informally based on what we hear and from whom, there are some problems with reliance on numbers or percentages of people who believe a proposition.


We see this in such things as “4 out of 5 doctors recommend …” or “99% of the experts agree …” and sometimes even more directly in the form “x-1 out of x agree that proposition Y is true – who are you to disagree?” This is the “10,000,000 Frenchmen can’t be wrong” argument.


In fact, the truth of a proposition is not dependent on the number of people who believe it (except for self-referential propositions such as “99% of the group believes that 99% of the group believes …)..


I think nearly everyone had the following conversation with their mother at some point (translate to your native language as needed).

(Since this response has been used nearly verbatim by early all mothers since time immemorial, it must be true.)

Me: “But Mom, everybody else is doing it!”

Mom: “I don’t care what *everyone* does, I care what you do. If *everyone* jumped off a cliff would you jump off too?”


In short the argument from preponderance of belief is a fallacy.


This is not to imply that there is not valuable information to be gained from knowing how the spectrum of belief in a proposition lays out, but as often used it is a variation on the argument from authority, except that the majority is taken to be the authority.


To make the point again:

You and I are esteemed members of the local chapter of <fill in choice>, and we have just signed up our 1000th member,

Further (can you believe it!?) we are all in attendance at the meeting.

I propose a resolution that to celebrate we all adjourn to the extremely expensive restaurant across the street for a lavish dinner, and that you should pay for all of it.

There are 999 of us who think this is a great idea. Why don’t you?




Garold (Gary) L. Johnson