What is Design Thinking? A Thorough Explanation from the Basics to Its Evolved Forms

First, we will introduce what design thinking actually is, along with its core concepts, origins, and historical background.

Definition and Basic Concept of Design Thinking

“Design thinking” is a methodology that places the user’s viewpoint at the centre, aiming to derive creative and feasible solutions. The key word here is “human-centred”. Rather than simply improving appearance, this method is about deeply understanding humans’ needs and behavioural patterns, and then creating solutions based on that understanding. Originally, it was the informal process that designers naturally undertook when developing products; nowadays it is widely used in business, education, and government.

Historical lineage and evolution of design thinking

In the 1980s–90s, competition centred on product functions and price. However, in the 2000s user experience (UX) began to be emphasised, and ideas needed to align with customer emotions and lifestyles. At that time, the human-centred design concept proposed by IDEO (led by Tim Brown) gained attention.

IDEO, a U.S. design firm based in Palo Alto, has been active since 1991, and in the early 2000s, during the growth of the internet and information society, design thinking emerged. CEO Tim Brown redefined design as a “methodology for problem-solving” and spread this into the business world. Subsequently, design thinking extended beyond business into education. In 2003, the d.school (Stanford University) was established at Stanford University to offer systematic learning of design thinking, producing many innovators. In Japan, the i.school, University of Tokyo was established in 2009. Non-design students and business people began to learn design as an approach to problem discovery and solving.

Tim Brown defines design thinking as a human-centred approach to innovation, one that integrates people’s needs, technological possibilities, and business success conditions.

Three-element model

Brown’s model involves three key indicators, and he states that the overlapping area of these three is essential for successful innovation:

Desirability (people’s desires/needs)

What users or customers really want; improving emotional experience or quality of life – a human-centred view.

Feasibility (technical standpoint)

Whether it is technically possible; development resources, infrastructure, cost viewpoint.

Viability (business sustainability/profitability)

Whether the business will stand and be sustainable; from a revenue and management sustainability view.

The area where all three overlap is where sustainable, valuable solutions (i.e., successful solutions) exist.

Three-element model

Double Diamond Model

Proposed by the Design Council (UK), the “Double Diamond” model explains the process of problem-solving through repeating “divergence” and “convergence” between Discover → Develop phases. This flow closely corresponds to the six-step design thinking process (Empathise → Define → Ideate → Prototype → Test → Implement).

◇The First Diamond◇

The first diamond focuses on the process of understanding and defining the problem.
It moves from divergence (Discover) to convergence (Define), forming a structure of exploration → definition.
The goal of this phase is to define the right problem to solve.

Discover:

In this process, designers explore users’ situations and challenges broadly. Methods such as user interviews, observational research, and data analysis are used to uncover hidden needs and insights that users actually face—rather than assumptions made by the team. The key here is to identify what the real problems are from the user’s perspective.

Define:

In this phase, the insights collected during the Discover stage are organised to clarify the essence and core of the problem. Common methods include persona development and customer journey mapping. The focus is on selecting and prioritising diverse information to ensure that the team reaches a shared understanding and agreement on the right problem definition.

◆The Second Diamond◆

The second diamond deals with the process of creating and implementing solutions. It progresses from a divergent phase, where a wide range of ideas are generated, to a convergent phase, where the most promising ideas are refined and implemented. This is represented as Develop → Deliver.

Develop:

In this phase, teams generate diverse ideas and potential solutions to the problems defined in the first diamond. Methods such as brainstorming, prototyping, idea sketching, and workshops are used to freely express ideas. The emphasis here is on quantity and diversity, rather than immediate feasibility.

Deliver:

At this stage, the ideas have taken tangible form, and the process moves toward implementing the optimal solution through repeated prototyping and testing. User testing is typically conducted to review user reactions and incorporate feedback, refining the solution to deliver genuine value. It is essential to ensure that the final output becomes a truly valuable and effective solution for the user.

Figure 2: The Double Diamond Problem-Solving Process

Figure 3: The Relationship Between the Double Diamond Model and the Six Steps of Design Thinking

The framework developed by Stanford’s d.school originally listed five steps (Empathise → Define → Ideate → Prototype → Test). Here we present a six-step version including Implementation/Launch.

1. Empathise

Conduct user interviews or observation to discover needs. Methods include Contextual Inquiry (visiting the user’s environment), Shadowing (observing users in their daily life), Ethnography (embedding in users’ environment), and creating a Customer Journey Map to design user behaviours, thoughts, emotions, and touchpoints. It is key to include extreme users and non-users to eliminate assumptions.

2. Define

Now that we have gathered information and data on user insights and needs, we enter the phase of clarifying challenges and setting the direction for solutions. The goal at this stage is to break down the problem into a "solvable" form and establish a focus that the team has agreed upon. This phase begins with the convergence of insights using the Affinity Diagram method — also known as the affinity mapping method — and the KJ Method.

The Affinity Diagram method is a technique for grouping large amounts of data (e.g., interview results, observation notes, ideas) by similarity or closeness in meaning (affinity). It is widely used in business settings as a way to "organize sticky notes," and is valued for its speed, practicality, and effectiveness in building shared understanding within a team. However, compared to the KJ Method, it is somewhat weaker in terms of "deep structuring" and "insight through written articulation."

The KJ Method is a qualitative data organization and analysis method developed by cultural anthropologist Jiro Kawakita, and the Affinity Diagram method itself originally has its roots in the KJ Method. It was originally used as an academic technique for creatively structuring vast amounts of fieldwork descriptions and similar material. Its procedures are more rigorous than the Affinity Diagram method, encompassing grouping, relationship mapping, diagramming, and written articulation — making it more oriented toward analysis and research, with a strength in building deep insights and hypotheses.

The significance of converging insights lies in condensing observations, quotes, and data derived from diverse findings into "meaningful clusters," thereby surfacing the essence of the problem. Following the convergence of insights, the problem statement is redefined. Here, emphasis is placed on thinking through written articulation, following the flow outlined below.

Problem Statement Development Flow: Facts → Insights → Needs → POV → HMW

Here, we will briefly touch on POV and HMW with examples.

POV (Point of View)

First, it is important to articulate the "core of the problem or challenge" from the user's perspective in a single sentence. The format includes: [Who], in what [situation], is struggling with [what / what they are unable to do].

(Example) If the theme is improving the library experience: "Parents with young children are looking for ways to keep their children engaged, because they want to use the library but struggle to stay when their children get bored."

HMW (How Might We…?)

Based on the POV, we transform the problem into an exploratory question: "How might we…?" It can take the form of a self-directed question such as "So, how might we approach this?"

(Examples) · "How might we create a library experience where children can enjoy themselves without getting bored?" · "How might we design a child-friendly learning space where parents feel comfortable using the library?"

Following the redefinition of the problem statement, we move on to articulating success criteria, including effectiveness metrics, constraints, and assumptions. One common pitfall is inadvertently broadening a challenge that was meant to be narrowed down, or introducing solution ideas based on hypotheses at a stage that should still be focused on extracting problems and challenges. In this phase, it is essential to stay strictly within the realm of the "problem statement."

③ Ideate

Once the location of the problem or challenge has been clearly articulated, we enter the ideation phase, where a broad range of ideas are generated through brainstorming and similar techniques. The goal here is to produce diverse and bold solutions in terms of both quantity and quality, so start by setting a time limit and focusing on generating as many ideas as possible to ensure volume. To avoid confusion over judgment criteria such as "what counts as a good idea?" in the later stages of ideation and testing, having pre-agreed standards and benchmarks helps prevent conflict during idea selection and pivot decisions.

In terms of specific methods, when generating a wide range of ideas as a team, the brainwriting technique can be used to collect a large volume of ideas. If the team hits a wall and ideas stop flowing, Crazy 8s — an ideation method proposed by Google Ventures — may also prove effective. A sheet of A4 paper is divided into eight sections, with one idea per section, and eight ideas are generated in eight minutes. The strength of this method lies in its ability to surface intuitive and unconventional ideas by locking thinking within a tight time constraint. Other representative ideation methods include SCAMPER, which involves exploring whether existing products or services can be improved from a different angle, and analogical thinking, which is considered well-suited for innovation and new business exploration and transforms ideas by drawing inspiration from other fields, industries, and cultures — making four key methods in total.

④ Prototype

This is the phase of rapidly creating prototypes with the purpose of "thinking through making," and giving form to ideas at an early stage. The goal is simply to visualize hypotheses and bring them to a testable state with the bare minimum required, so start with low-fidelity prototypes. From there, create experience storyboards and service blueprints, and design "experiments for learning" starting with the highest-risk hypotheses. For those who want to learn more about service blueprints, please visit Service Blueprints for Visualizing Customer and Employee Experiences.

One important pitfall to avoid here is over-building. The purpose is ultimately to "think and learn." It is perfectly fine to work at a level of roughness that allows you to discard work without hesitation, so focus first on visualizing your hypotheses. It is also important to visualize the value proposition, pricing, and onboarding flow.

⑤ Test

After going through the prototype stage of visualizing hypotheses, we enter the testing phase. In this phase, hypotheses are validated through user behavior, statements, and reactions. By gathering feedback from users and stakeholders and putting it to use, we further refine products and services at the prototype stage. Methods include a series of usability tests, concept tests that measure users' comprehension, appeal, and value acceptance, as well as a method called smoke tests, which measures acceptance signals through landing pages and advertisements. Key points to be aware of include the risk of biased data when sampling from an in-house target population, and the risk of relying on users' subjective self-reporting. Here, we should prioritize behavioral data that can be measured objectively (clicks/drop-offs).

⑥ Implement/Launch

After repeated user testing, validation, and refinement, we finally reach the implementation/launch phase where the product or service is introduced to the market or the field. The goal of this final phase is to reflect the learnings from testing in the product or service, deploy it in real-world operations, and continuously deliver value. This involves creating operational manuals with actual deployment in mind, leveraging feature flags, as well as establishing onboarding processes for the organization and building the definitions and infrastructure for measurement design.

The most important thing is not to treat the work as "done once it's built." No matter how well a product or service has been crafted around user value, if the cycle of measurement, improvement, and PDCA is broken, it will be difficult to maintain user support over time. Furthermore, if the environment where the product or service is delivered is not properly set up, stumbling blocks during the operational phase become likely. Training, customer communication design, and planning must all be developed in parallel.

The Meaning and World View Beyond Implementation

Regarding the six steps of design thinking systematized by the Stanford Design School, Andy Ogden of ArtCenter and other faculty members have voiced the opinion that while the framework is clear and easy to use, applying it in a stepwise and mechanical manner as a template can feel slightly misaligned with the essence of design. When applying this framework in practice, it is common to move back and forth between steps — and not being afraid of that is the key to success.

It seems that the "world view" created from the insights and synthesis work gained through the practice of design thinking, the "meaning" that products and services hold for users, and the "vision" are all closely interconnected. The world view newly proposed through design thinking, and the products, services, and business models created within it, give users new meaning — and that meaning becomes the user scenario.

To illustrate what it means to grasp a world view, a clear example would be Studio Ghibli and Disney. The world view depicted by Studio Ghibli differs from that of Disney — it is distinctive and richly imaginative. Disney, too, has succeeded in creating its own unique world view and spaces. Both have built systems through which users can instantly grasp their world view and feel the meaning being offered.

Creating a world view that resonates with users around the globe, generating new ideas that lead toward that world, and connecting it all to a brand — successful brands follow exactly this kind of process. And at the heart of it all is, once again, "a world view and meaning that generate empathy."

Up to this point, we have introduced the concepts and methods of design thinking. However, design thinking is no longer limited to product development alone; it continues to evolve as an approach to tackling increasingly complex and multilayered challenges, with applications expanding into areas such as organizational transformation, public policy, and education. This evolution is closely tied to the growing complexity of the problems facing society today—issues that can no longer be addressed through single, straightforward solutions.

Challenges such as climate change, demographic shifts, and digitalization cannot be adequately handled through conventional problem-solving processes alone. As a result, further evolution and expansion of design thinking are being called for. In response, growing attention is being paid to the integration of design thinking with thought processes from other disciplines.

Integration with Other Approaches such as Service Design and Systems Thinking

While design thinking excels at solving individual, clearly defined problems, many of today’s challenges require the design of entire service experiences and the optimization of interdependent systems as a whole. From this perspective, integration with service design and systems thinking is becoming increasingly important.

Service design is an approach that views the entire set of customer touchpoints as a “service journey” and designs a comprehensive user experience that includes not only the moment of service use but also the stages before and after. This makes it possible to translate user insights gained through design thinking into more practical, operationally grounded services.

Systems thinking, on the other hand, is a framework for understanding the overall structure in which multiple elements interact with one another and for designing optimal solutions at the level of the whole rather than in isolated parts. When addressing large-scale, complex social challenges—such as environmental issues or urban policy—it is essential to combine the human-centered approach of design thinking with the holistic, big-picture perspective of systems thinking. By doing so, efforts move beyond merely solving isolated problems and instead contribute to the design of more sustainable social systems.

Connection to speculative design

Although design thinking is strong for solving current problems, there is also a movement to link it with future-oriented approaches for addressing highly uncertain challenges. One example is speculative design.

Speculative design presents “what if” scenarios based on future changes in technology and society, and, by working backwards from desirable futures, seeks to discover problems and issues that do not yet exist. Its goal is not immediate product/service development but to question values and ethics in society.

By connecting design thinking with speculative design, a “two-layered design practice” becomes possible: one that addresses short-term problem solving and also considers long-term future scenarios. By exploring future possibilities while keeping current constraints in mind, we can generate more sustainable and ethical solutions.

What design thinking must look like moving forward

Design thinking is not a mere business buzzword—it is a methodology for human-centred problem solving, and its range of application is expanding.

Its importance continues to increase in areas such as AI, IoT, sustainability, and social inclusion. The point is not only the “method”, but how deeply the attitude of design thinking is embedded—i.e., the “ability to pose the right questions.”

Many conventional problem-solving approaches emphasise how efficiently to find answers to a given problem. But many of today’s societal challenges share features like: “The problem itself is unclear” or “It’s not decided which problem should be prioritised.” When you don’t clearly know what problem you’re facing, you cannot know what to tackle. Thus, the ability to accurately frame the problem will become ever more emphasised.

The next stage of design thinking will be based on “asking the question”, and by combining it with speculative design, future-insight, scenario planning, and other methods, it will become an orientation for creating sustainable and adaptable solutions in a highly uncertain society.

Design thinking is not a method that has “ended.” Rather, it continues to evolve in response to the demands of the times. It is expanding beyond conventional product development and service improvement to address societal challenges and future uncertainties. To understand design thinking, it’s key to first learn concepts such as the “Three-element model (Desirability, Feasibility, Viability)” and the “Double Diamond model.” These underscore that design thinking is not just an ideation method but a process of exploration and integration. By following the six steps—Empathise, Define, Ideate, Prototype, Test, Implement—you can design truly human-centred approaches. Furthermore, by combining design thinking with next-generation methods like speculative design you can move beyond solving today’s problems to discovering new issues and formulating new questions for the future. In short, the true nature of design thinking is a flexible mindset that adapts across domains—and at its core remains human experience and value. Therefore, design thinking will continue to be a vital approach for shaping the future.

Ref：
the Faculty of Design, Kyushu University.「Design Thinking」
・The history of design thinking
・British Design Council
・『"Strategic Creativity: Awareness through Drucker, Creation through Design Thinking, and Strategy Implementation through Porter" by Hideki Yamawaki