How to Detect Charlatans: Taleb's Via Negativa Test

Here's a heuristic that catches charlatans almost every time: they give positive prescriptions. Experts give negative ones.

A charlatan says: "Do this. Follow these steps. Implement this framework. Here are ten things you need."

An expert says: "Avoid this. Stop doing this. Don't do this. Here's what kills you."

Why This Works

Positive prescriptions are easy to sell. People want to gain, not lose. "Do these ten things and you'll be rich" is a more appealing message than "Stop doing these things or you'll be poor."

Positive prescriptions are hard to verify. If I tell you "follow my ten-step system" and you fail, you can blame yourself for not following it correctly. The system is unfalsifiable.

Positive prescriptions from charlatans are consequence-free. The charlatan recommends and walks away. If the recommendation fails, the charlatan moves on to the next client. They bear no cost for being wrong.

Negative Prescriptions Are Different

Negative prescriptions are hard to sell. Nobody wants to hear what to avoid. It's boring. It doesn't promise transformation.

Negative prescriptions are easy to verify. If I tell you "stop eating refined sugar" and you get healthier, you know the advice worked. There's no ambiguity.

Negative prescriptions from experts carry accountability. An expert saying "stop doing this or you'll suffer" is implicitly willing to be judged on the outcome. They're confident enough to stake their credibility.

Domain Examples

Wealth: - Charlatan: "Buy this asset. Invest in this opportunity. Follow my trading system." - Expert: "Stop buying things you can't afford. Stop taking on debt. Stop paying fees."

Health: - Charlatan: "Take this supplement. Buy this device. Follow this protocol." - Expert: "Stop smoking. Stop being sedentary. Stop sleeping five hours."

Weight Loss: - Charlatan: "Do this workout. Eat these foods. Use this supplement." - Expert: "Stop eating seed oils. Stop eating refined sugar. Stop eating ultra-processed food."

Relationships: - Charlatan: "Use this technique. Say these words. Follow this framework." - Expert: "Stop being dishonest. Stop pretending. Stop prioritizing winning over connecting."

Business: - Charlatan: "Follow this business model. Implement this strategy. Use this framework." - Expert: "Stop cutting costs at the expense of quality. Stop taking on excessive debt. Stop trying to be everything to everyone."

Notice the pattern. Charlatans add. Experts subtract.

Why It Matters

This heuristic helps you avoid wasting time and money on fraudulent advice.

It also helps you find actual expertise.

When someone has real knowledge, they often lead with what's wrong and what to avoid. It's the knowledge they're confident about.

When someone is selling, they lead with what's right and what to do. It's the promise they're marketing.

The Edge Cases

Real experts sometimes give positive prescriptions. A doctor might say "Do this exercise to strengthen your back." This is still expert advice. How do you distinguish from charlatans?

Look for the foundation. Real positive prescriptions are built on negative knowledge. "Do this exercise because these other things will harm you. Stop doing those harmful things first, then do this."

Charlatans skip the foundation. "Do this exercise and you'll be strong." No explanation of why, or what to avoid first.

The Application

When evaluating advice:

Is it primarily positive prescription ("do this") or negative prescription ("avoid this")?
If positive, is there a foundation of negative knowledge underneath?
Does the advisor have skin in the game if the advice is wrong?
How much of the advice is about addition vs. subtraction?

The more an advisor leans on negative prescription (with credibility stakes), the more likely they know something.

The more they lean on positive prescription (with consequence-free marketing), the more likely they're selling.

The Deepest Version

Via negativa — defining things by what they're not — is actually more powerful than positive prescription even in legitimate contexts.

A good definition of health might be: "not sick, not injured, not fatigued, not in pain." This is more robust than "feeling good," which is vague.

A good definition of wealth might be: "not in debt, not dependent on a single income, not at risk of ruin." This is more robust than "having a lot of money."

The negative definition is harder to mislead yourself with.