Most PMF models describe symptoms (high demand). A causal model identifies the root cause: a pre-existing, blocked project a customer must complete. This "pull" is the force that shapes a successful product, not vague "pain points" or theoretical ROI.
The 'pull' from a customer's blocked project is not just a demand signal; it's an evolutionary pressure. This force dictates how the product must work, how customers want it priced, and what features are required. Successful startups are those that evolve to fit this external force.
It's possible to make sales without understanding why a customer is truly buying. To find the real 'pull,' challenge their interest by asking why their current solution isn't good enough. This forces them to articulate the core limitation they face, revealing the actual motivation.
At the pre-idea stage, common activities like making decks or extensive customer interviews often yield no paying customers. The most direct path to validation is to find one person in your target market and convince them to pay you to solve a problem manually. This proves real demand exists.
Startups with a few customers often serve different needs. To find a scalable model, analyze which customer 'pulled' the product out of your hands the fastest and with the least convincing. This demonstrated pull is a better indicator of a repeatable market than contract size or a customer's prestige.
To determine if you have real demand, analyze who drives the sales process. If you are constantly following up, offering pilots, and pushing for meetings, that's 'push.' If the potential customer is proactively scheduling next steps and asking for contracts, that's 'pull'—the only scalable force.