What World War Z Can Teach You About Critical Thinking


“How did Israel know?”

The rest of the world had been taken over by a zombie apocalypse.

A virus had swept through the human population, turning people into the undead in seconds.

After being “turned,” the zombies would swarm wherever they could find enough humans. Whole streets would fill with rivers of zombies as they frantically tried to find a healthy human to bite. (Apparently, these are the “bite-and-forget” kind of zombies, not the ones that actually eat people).

The United States was almost completely overrun.

Entire continents had fallen.

And yet, ten days before the disaster struck, a tiny country on the West Bank had built a wall — Israel.

Not just any wall, but a towering concrete rampart that made it impossible for zombies to enter the city.

Israel had saved themselves and their citizens from the zombie apocalypse.

But how did they know?

Ten days before the apocalypse struck, they had received an email from an Indian general with the word “zombie.”

Of course, most of the Israeli intelligence officers scoffed at the idea and were prepared to ignore it. But there was one who was not.

The Tenth Man

To avoid unwanted surprises like The Yom Kippur war with Egypt and Syria in 1973, Israel had instituted a policy known as “the tenth man.”

It goes like this:

When nine people agree on something, it’s the tenth man’s responsibility to disagree no matter how improbable the idea.

When the email came through that zombies were on their way, the tenth man proposed that they prepare for a zombie invasion, no matter how ridiculous the idea seemed.

While this is obviously an extreme example, there’s an important lesson there that you can use to avoid fooling yourself.

Prove Yourself Wrong

If the tenth man hadn’t spoken, Israel would have been overrun by zombies like the rest of the world.

The tenth man forced Israel to consider an alternative view point, something we humans usually resist.

As Michael Shermer puts it in his book *[The Believing Brain](http://www.amazon.com/gp/product/B00D9TAAB8/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00D9TAAB8&linkCode=as2&tag=armlegsathl0b-20&linkId=W66EDCRVLB4MO4HT)*, the human brain is a “belief engine.”

We are pattern-seeking machines. We look for connections everywhere. We get things right a lot of times (lifting weights does help muscle growth3), but we often get things totally wrong (ketosis and fat loss).4

A better way to implement the “tenth man policy” would be as follows:

Whenever nine men agree on something, it’s the tenth man’s responsibility to present a case for an alternative view point — no matter how ridiculous the idea sounds.

If his evidence is still inferior and conflicts with the consensus of the other nine men, then they go through with their original plan. If the tenth man’s ideas prove to be superior, they explore his ideas further.

Luckily, this is how good researchers think and how good science is done.

[Credible authors](http://evidencemag.com/the-10-most-credible-health-and-fitness-bloggers-you-can-trust/) often list the limitations of their work and address possible explanations for strange results. They constantly try to disprove their ideas and destroy their beliefs. If their ideas hold up, then they’re probably close to the truth.

This is also why the peer-review process is so critical to research. It gets other people to critically examine the study. It gets many “tenth men” to question the ideas of a paper. According to Michael Shermer, science is the “ultimate bias-detecting machine.”2

How to Think Like the Tenth Man

Before accepting something as fact or getting attached to new beliefs, put yourself in the shoes of the tenth man.

When every other part of your brain is convinced that gluten is the enemy, fructose is a poison, and ketosis is the secret to effortless weight loss — before you make any change to your life — think like the tenth man.

Try to disprove your ideas with the best evidence you can find. If you find good evidence against the idea/intervention, then it’s worth waiting before making any drastic changes.

Here’s where the “tenth man” idea needs some work. In the movie, Israel assumes that the tenth man is right and they build a wall.

Instead, you need to assume that he’s wrong. You need to do what researchers call “rejecting the null hypothesis.” Whenever you’re presented with a new claim, especially a strange one that seems improbable, the burden of proof is on the person making the new claim.

Because humans are always looking for patterns and finding them where there are none, your tenth man should have some damn convincing evidence.

Here’s another important difference. Unlike Israel, you don’t have unlimited financial support from the United States to blow on building walls (or buying supplements). Point being — take the default position that whatever supplement/diet claim/workout program you’re looking at is wrong or ineffective until it’s proven to be correct or effective.

There are times when you don’t have great evidence available, but that doesn’t necessarily mean something is wrong, dangerous, or ineffective. In these cases, the risk of trying the intervention should be minimal, and you should still be able to find some plausible indirect evidence that you can use to justify trying it.

An Example of the Tenth Man in Action

Let’s say you see a new supplement being marketed as the ultimate recovery tool. Let’s say it’s called Surge Recovery®.

It promises that you can “…speed up your body’s ability to recover and build muscle by a minimum of one full day…” and that with their “… mix of nutrients post workout, the vast majority would make consistent, continual muscle-mass gains.”

It looks convincing enough, and the dude at the gym who drinks it is huge, so you start to pull out your credit card. Then the tenth man pipes up:

“Hold on there, bro. Are you sure this stuff is worth the money? What if it’s no better than chocolate milk? That’s cheap, tasty, and you drink it already.”

So your credit card snuggles back into place, and you find an article called “An objective comparison of chocolate milk and Surge Recovery,” by some guy named Alan Aragon. Alan devours their claims like a ravenous zombie, your tenth man turns out to be right — and you’re $50 bucks richer.5


*If you mess with a zombie, you better be prepared to do battle.
Photo via Alan Aragon*

If you can’t find good evidence to support making a decision that involves a high risk or cost, don’t do it.

“When you find yourself on the side of the majority, you should pause and reflect.”

– Mark Twain

A lot of people read that quote as “if you find yourself on the side of the majority then they’re obviously wrong because they’re part of conventional wisdom and Monsanto and big business and therefore my weird fringe idea with no supporting evidence must be correct.”

Or something like that.

The point of using the “tenth man” policy is not to do the opposite of what you think is right. It’s to constantly question your beliefs and force yourself to examine all of the evidence — not just the stuff that supports your ideas.

Granted, Israel ended up getting overrun when zombies started climbing over the walls, and millions of people still died, but you get the point — we still can’t stop all zombies. Maybe they should have thought a little harder about how to keep the zombies out instead of just building a wall.

You need to train your brain — at least a tenth of it — to act like an intellectual watch dog. That one tenth might be the most important part.

At least Brad Pitt got out alive. Whew.



> Did you enjoy this article? [Click here to check out my book, *Flexible Dieting](http://evidencemag.com/flexible-dieting-book)*. Want an even more in-depth education on how to lose weight, build muscle, and get stronger and healthier? [Join Evidence Mag Elite](http://evidencemag.com/elite) and get member’s-only reports and interviews.

### References

1. Pitt B, Enos M, Kertesz D. World War Z. (Foster M, ed.). 2013.

2. Shermer M. The Believing Brain. St. Martin’s Griffin; 2011.

3. Schoenfeld BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res. 2010;24(10):2857–2872. doi:10.1519/JSC.0b013e3181e840f3.

4. Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears B. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. Am J Clin Nutr. 2006;83(5):1055–1061. Available at: http://ajcn.nutrition.org/content/83/5/1055.long.

5. Aragon AA. An objective comparison of chocolate milk and Surge Recovery. The Alan Aragon Research Review. 2008:2–5.

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