Can 'Drink Eight Glasses a Day' Teach Anything?

Years ago, I pointed out a debunking of an easy-to remember (but wrong) bit of conventional wisdom that I'd never put much stock in anyway: Drink eight eight-ounce glasses of water every day.

I was, in part, naively hoping I wouldn't have to hear it much anymore.

Image by Joah Brown, via Unsplash, license.

I was wrong, if this morning's encounter with yet another debunking is any indication.

That silly rule is still around enough that debunking it for the millionth time will still constitute news for some people.

But rather than merely be annoyed with the persistence of this myth, perhaps it can serve a purpose -- as a ready-made example of a type of failure in how knowledge gets transmitted -- with its persistence keeping it relevant while also becoming part of its own cautionary tale.

In his recent book, Fossil Future, energy expert Alex Epstein devotes significant time to explaining the idea of a society-wide knowledge system, or way that knowledge is sought, disseminated, interpreted, and deployed. (Many people have a half-baked notion of this in the form of the idea of a "mainstream media." The press is indeed part of the knowledge system, but they aren't the whole, which also includes other institutions, like universities and other research institutions, certain government agencies, think tanks, and non-government agencies.

Relevantly, this system -- like any other -- is susceptible to human error.

For example, any error in epistemology (e.g., how people think we acquire knowledge and how they process new claims to knowledge) can lead to errors beyond simple mistakes. Mistaken ethical or political priorities can lead to biased or wrong presentations, interpretations, or applications of knowledge claims.

All of this sounds abstract, but some simple concrete examples might make it easier to understand that a knowledge system can easily cause widespread misconceptions.

That's where eight glasses a day comes in.

Everyone has heard this, and it's easy to explain where it came from and why it's such a tenacious myth, nearly a century after it started: Scientists determined that we need about 64 ounces of water a day. Sloppy reporting left out the bit about how most of that amount comes from food and other liquids already in a typical diet. Someone noticed that a typical glass of water is eight ounces, which, through the magic of division, led to a memorable rule. And our predilection for accepting rules from on high/not wanting to think too hard about such rules -- both thanks to widespread, implicit bad philosophical ideas -- caused the rule to catch on.

It's easy to debunk, and from there, one can ask, If so many people 'know' this falsehood about something so easily debunked, what other, more complex things might the conventional wisdom be wrong about? Or, If it's so easy to screw up something as simple as how much someone needs to drink every day, what else have people gotten wrong?

That question won't immediately change someone's mind (which is fundamentally impossible anyway), but it might help them start questioning things on their own, and that's what we should really be after, anyway.

Just like taking things on faith and not questioning authorities are holdovers from our culture's religious history, so is the pernicious idea that we need to "win" arguments all at once or gain huge numbers of converts (or even can, in any meaningful sense of the term).

Cultural change isn't as simple as getting crowds to dunk themselves into a river and profess allegiance to a cause that is meaningless beyond taking orders. Meaningful cultural change takes independent thinking and occurs one mind at a time.

-- CAV