Design thinking: the process, its stages and its critics

What is it and where does it come from?

Nielsen Norman Group attributes the term to David Kelley and Tim Brown of IDEO, with Roger Martin, in the 1990s. The central idea is that design is not only aesthetics: it is a way of solving problems that can be applied to a service, an internal process or a product.

The best-known version is the one from the d.school at Stanford, which presents the approach as five modes: empathize, define, ideate, prototype and test. Its Design Thinking Bootleg is a deck of cards with tools for those modes, and its own introduction invites you to start wherever you like rather than in a fixed order.

The model has variants. NN/g uses six phases within an overall flow of three blocks (understand, explore and materialize), with implementation as the final phase, and states that each phase is meant to be iterative and cyclical rather than strictly linear. Interaction Design Foundation also mentions other models, such as AIGA’s Head, Heart and Hand or the Design Council’s Double Diamond.

Why does it matter to a designer?

Because it offers a shared language for teams that are not from design. NN/g recalls that companies historically used design “only to touch up a product’s aesthetics”, which produced products that missed customers’ real needs. A product manager and an engineer who understand the difference between defining and solving a problem make better decisions together. The approach also forces the team to see the problem before proposing the solution, something many teams skip.

And it makes research visible. Empathizing means going out and talking to people, and that stage provides the raw material for everything else. If that stage disappears, the process becomes a sticky-note brainstorm.

How do you apply it, step by step?

The order is a guide, but these are the typical activities of each stage:

1. Empathize. Interviews, observation and, if time allows, user interviews. The goal is to understand the context, not to validate your own idea.
2. Define. Group what you learned and write the problem as a concrete question, for example: “How can a parent with little time find out what their child spent this week?” A good definition limits the possible solutions without closing them off.
3. Ideate. Generate many ideas before choosing. Techniques such as crazy 8s help you move past the first idea.
4. Prototype. Build something low-fidelity to answer one concrete question. A sketch is enough if the goal is to test an idea.
5. Test. Put the prototype in front of users, watch what they do and decide what to change. This phase sends the team back to empathy, which is why the process is iterative.

The step that is most often forgotten is implementation. NN/g calls it the most important part of design thinking and the phase most often forgotten. A solution that never reaches production has solved nothing.

What are the criticisms?

The debate is serious and worth knowing.

• Norman: a public relations term. In the 2010 essay “Design Thinking: A Useful Myth”, Don Norman wrote that design thinking is “a public relations term for good, old-fashioned creative thinking”. The essay adds that designers can be creative, but “they are hardly unique”. He ends ironically: the term can live while it is useful and be put away once the transformation of design is complete.
• Sticky notes and formulas. Natasha Jen, a Pentagram partner, gave the talk “Design Thinking is Bullshit” at the 99U conference in 2017. According to Core77’s summary, she objects to Post-its, hexagons and oversimplification: distilling a complicated process into an easily replicable formula isn’t always possible.

Defenders argue that the principles (understand before solving, iterate, test with users) do not belong exclusively to one method. Norman, in the same essay, accepts the term as a useful myth that gets companies to take design seriously.

When should you NOT use it?

• When the problem is already well defined and what is missing is execution.
• When you have no access to users. Without empathy, the result is an opinion with a nice format.
• When the decision has already been made and the workshop only serves to look participatory.
• When you only want ideation. If there are no criteria or prototypes after the ideas, the exercise fades away.

In those cases, a more specific process, such as the double diamond or a design sprint, often produces better results.

Example

Illustrative example: a small bank wants to reduce calls from customers who do not understand their monthly statement. The team talks to ten customers and discovers that many are looking for one thing: whether a charge is fraud. They define the problem as “how to tell in 10 seconds whether a charge is mine”. They ideate six ways to present it. They prototype two on paper and test them with five people. The version with a list of charges grouped by merchant wins. Before implementing it, the team agrees how it will measure the result: calls per statement. Without that last part, the process would not have closed the loop.

For your next project: write the problem as a one-sentence question and check whether someone on the team could answer it today. If not, start with empathy.

Common mistakes

• Skipping empathy and jumping straight to ideas.
• Defining the problem as if you already had the solution: “We need an app” is not a problem.
• Staying in the workshop, with no prototypes or tests.
• Testing with colleagues instead of real users.
• Not planning implementation, the phase NN/g considers the most important and most forgotten.
• Treating the stages as a rigid sequence, when the approach itself presents them as iterative.

Sources

• Design Thinking 101, Nielsen Norman Group (Sarah Gibbons, 2016, revised July 2026)
• What is Design Thinking?, Interaction Design Foundation
• Design Thinking Bootleg, d.school, Stanford
• Design Thinking: A Useful Myth, Don Norman (Core77, 2010)
• Natasha Jen’s Design Thinking is Bullshit Argument, Core77 (2017)