Sales in 2026
For far too long, sales has been a collection of tricks and techniques. But successful sales is not about selling harder. It is about a system that works.
Build your own sales organisation on the basis of Diagnostic Selling. An organisation that creates its own demand, understands why customers decide and consistently closes profitable agreements.
Diagnostic Selling is a sales method and design model for sales organisations in which the salesperson does not begin by persuading, presenting or quoting, but first systematically establishes which of three conditions for a responsible decision is missing: Stake, Trust or Urgency.
The diagnosis then determines the smallest justified next step — including the option to wait, to stop or to sell nothing.
Within the Greg Trinidad method, this way of deciding is carried through to the entire commercial organisation: from demand generation and qualification to connection, baseline measurement, confirmation, explicit agreement, contract, onboarding and aftersales.
The Fire Triangle
Every purchase — however complex — requires three elements to be present at the same time. The Fire Triangle makes visible which element is missing. That determines your next step, not your gut feeling.
Not the organisation’s problem, but how this person experiences it personally. Without that, nothing happens, however good your solution is.
“What changes for you personally once this is solved?”
If the answer stays vague, there is no stake. Then there is no point in carrying on.
Not whether you are likeable, but whether he can carry the risk of choosing you and being held accountable for it later.
“Who will be held accountable if it goes wrong?”
That is a question about him. The answer tells you whether he can handle the choice.
Waiting is the safest decision there is: if you do nothing, you are never proved wrong. That is why you cannot invent urgency with a deadline.
“What happens if you leave this as it is for another year?”
If the answer is "nothing", there is no urgency. And then he will not buy now.
The model is set out in De Vuurdriehoek, its application in sales in Diagnostisch verkopen (in Dutch). Both on vuurdriehoek.nl, where part I of each can be read free of charge.
How it works
Diagnostic Selling is not a script. It is a frame of thinking that helps you ask the right question at the right moment — and gives you the courage to sometimes do nothing.
The first phase is listening and observing. Not presenting. You ask questions to understand which of the three conditions is missing — and you are prepared to be honest about what you see.
Based on what you observe, you establish what is missing. Is Stake missing? Then your job is to inform, not to pitch. Is Trust missing? Then providing proof is the next step, not sending a proposal.
Not the biggest leap — the smallest step that is realistic given the diagnosis. Sometimes that is a follow-up. Sometimes it is waiting. And sometimes it is saying honestly: "This is not the right moment for you."
A salesperson who knows when to stop earns more trust than one who always keeps pushing. Diagnostic Selling explicitly recognises that selling nothing is sometimes the best diagnosis.
A real-world example
“I need to discuss this internally first.”
The same remark can have three different causes. And each cause calls for a different next step.
Possible explanation 1
The person in front of you does not yet see what it means for them. More product information will not help.
Possible explanation 2
They fear the risk, or need to be able to convince others. Then substantiation matters more than a new pitch.
Possible explanation 3
The situation can wait. Then agreeing a later moment is wiser than adding pressure.
The point: Diagnostic Selling does not decide in advance which explanation is right. You first establish what is really going on, and then choose the smallest justified next step.
The difference
Not consultative selling
Diagnostic Selling is often compared with consultative selling, SPIN Selling, the Challenger Sale and solution selling. They all start with questions rather than a pitch. That is why they look alike. But they ask a different question, and they allow a different outcome.
Consultative selling asks what the customer needs. Diagnostic Selling establishes why they are not yet deciding.
| Method | Central question | Possible outcome |
|---|---|---|
| Consultative sellingMack Hanan, 1970 | What does this customer need? | Fitting advice and a proposal |
| SPIN SellingNeil Rackham, 1988 | How do I get the customer to state the value of a solution themselves? | Commitment to a next step towards a purchase |
| The Challenger SaleDixon & Adamson, 2011 | Which new insight changes how the customer sees their situation? | The customer rethinks their approach and chooses whoever brought the insight |
| Solution sellingMichael Bosworth, 1980s | Which pain does our solution solve for this customer? | A solution that matches the customer's pain |
| Diagnostic SellingGreg Trinidad | Which condition for a responsible decision is missing: Stake, Trust or Urgency? | The smallest justified next step, including waiting, stopping or selling nothing |
This comparison shows the centre of gravity of each method. It is not a claim that these methods never look at decision-making. Asking questions and exploring needs is not, in itself, unique to Diagnostic Selling.
Frequently asked questions
No. Consultative selling maps the customer's needs in order to recommend the best-fitting solution. Diagnostic Selling first establishes which of three conditions for a responsible decision is missing: Stake, Trust or Urgency. The diagnosis determines the smallest justified next step, including the option to wait, to stop or to sell nothing.
No. SPIN Selling is a questioning technique that gets the customer to state the value of a solution themselves. The Challenger Sale revolves around a new insight with which the salesperson takes control. Solution selling looks for the customer's pain in order to offer a solution for it. Diagnostic Selling does not begin by persuading, presenting or quoting, but first establishes what is missing for a responsible decision. And it is not only a conversation technique, but also a design model for the entire sales organisation.
Because they all ask questions before proposing anything. The difference lies in what you want to establish with those questions, and in what you are allowed to do afterwards. A customer can have a clear need and still not decide. Diagnostic Selling finds out why.
No. A proposal can be the right step, but only once the diagnosis makes clear why it is the smallest justified next step.
Greg Trinidad. He links the method to his Fire Triangle model. The model is set out in De Vuurdriehoek, its application in sales in Diagnostisch verkopen, both on vuurdriehoek.nl.
There is no standard package and no price list. It depends on your current commercial situation and what you want to achieve. A first conversation is without obligation. If a more extensive sales diagnosis is needed, we agree in advance what it involves and whether there are costs attached.
Book a diagnostic call. We start with the diagnosis — not with the proposal.