Differential Diagnosis in Negotiations

Misdiagnosing in negotiations can have dire effects.

“They’re being unreasonable.”

I’ve heard that sentence in more negotiations than I can count.

And almost every time, it’s wrong.

I was recently watching The Pitt, where, as a teaching hospital, newly minted doctors are required to present not only a diagnosis, but a list of differential diagnoses.

In medicine, differential diagnosis is the process of identifying the cause of a patient’s symptoms by considering multiple possible explanations and systematically ruling them in or out.

At its core, it is the discipline of not settling on the first explanation.

What if we applied that same discipline to negotiation?

What if, instead of locking onto a single story, we generated multiple working explanations?

Most negotiators don’t do this.

They pick a story and start defending it.

If the story is wrong, everything that follows is wrong.

In medicine, a misdiagnosis can cost a life.

In negotiation, it can create confusion, escalate conflict, and damage relationships that didn’t need to break.

A differential approach to negotiation is simple in concept:

Generate multiple explanations for behavior and systematically test them before committing to one.

A case in point

Not too long ago, I was mediating a case where I was told the issue was money. There simply wasn’t enough to support the raises the union was proposing.

But once I caucused with each side, it felt like two different conversations were happening.

The employer focused almost entirely on budget constraints.

The union kept returning to shift assignments.

Both sides were frustrated. The employer assumed the union was being difficult. The union felt they weren’t being heard.

They weren’t wrong about what they were experiencing. But they were wrong about why it was happening.

What would have changed if, instead of locking onto one explanation, they had asked:

What could be driving this behavior on the other side?

Because the reality was more complex.

There were real financial constraints.

But there was also flexibility in how shifts were assigned, and that’s where much of the tension was coming from.

What looked like a disagreement about money was, in part, a conflict about working conditions.

And until that was understood, the conversation couldn’t move.

Start with a better question:

“What are all the plausible explanations for what I’m seeing in this negotiation?”

Instead of one story, you generate several:

• It’s about money

• It’s about internal politics

• It’s about fear of precedent

• It’s about loss of face

• It’s about miscommunication

• It’s about distrust of the process

But generating possibilities isn’t enough. You have to test them.

Just like in medicine, you don’t pick one and defend it. You probe the system.

You test by moving the system:

• You ask a question and watch what tightens

• You float a proposal and watch what breaks

• You shift the framing and watch what suddenly matters

What you’re looking for is simple:

Which explanation best fits the behavior?

A practical shortcut:

If, in real time, you can ask yourself:

“What are three other explanations for what I’m seeing?”

You’re doing what medicine calls differential diagnosis.

In negotiation, it’s something else:

Disciplined curiosity under pressure.

Most negotiators don’t get stuck because they lack skill.

They get stuck because they fall in love with their first explanation.

And once that happens, they stop seeing the room clearly.

The work is to stay open just a little longer than is comfortable.

Because that’s where the real problem reveals itself.