The mnemonic CATWOE is a systematic thinking technique developed as part of the Soft Systems Methodology (SSM). Its six elements—Customers, Actors, Transformation, Weltanschauung (meaning worldview in German), Owner, and Environmental constraints—help explore a system by underlining the roots that involve turning inputs into outputs [1].
CATWOE is valuable for uncovering insights in complex situations characterized by multiple goals, diverse perspectives, varying assumptions, and differing logics among numerous stakeholders.
A Background of SSM and CATWOE
SSM was first introduced by Peter Checkland and his colleagues, who researched how to apply systems engineering approaches to solve management and business problems at Lancaster University [2].
SSM helps investigate an unstructured problem situation by questioning what operations a system should perform and why. It opens a “soft” investigation into what the system should do, which can then be used to precede the “hard” investigation into how the system should do it.
Because organizational stakeholders can have divergent views on a system’s purpose and the problem to be addressed, SSM encourages an inquiry-based process in which the investigator works not as an expert but as a facilitator, supporting organizational actors as they define their system’s purpose(s) and functions.
SSM explicitly models the perspectives of various people (actors), representing their varied beliefs about an organization’s effectiveness, purpose, and people’s perceptions of current information systems within the organization. This helps identify and address problems holistically rather than following a local optimization approach.
The classic SSM inquiry has seven stages, as shown and explained (in brief):
The goals of each of these seven steps are as follows [5]:
- Steps 1 and 2: Identify real-world situations that stakeholders consider problematic. Describe and diagnose the current situation. Use a “rich picture” [6] to graphically represent stakeholders and their relationships to develop a holistic view of the problems.
- Steps 3 & 4: Develop a root definition that precisely describes the essence of the relevant system. Generate a conceptual model that indicates a proper interpretation of the modeled system.
- Step 5: Compare the model with the real world. Engage stakeholders to discuss changes that could improve the situation.
- Step 6: Analyse feasible and desirable change. Gain insights from organizational stakeholders, particularly those who will be affected and those involved in implementing changes.
- Step 7: Implement the changes. Avoid upsetting too many people while still achieving the objectives the change was supposed to achieve.
CATWOE is used in Step 3 to develop a Root Definition by taking the messy arguments of the real world caused by people with different perceptions as input to create a defendable, rational, and well-formulated conceptual model.
The purpose of a root definition is to define the system in a structured manner, ensuring that the analyst understands what the system will do and how it will do it. It follows a recurring pattern of the form: What, How, and Why.
Root Definitions, like mission and vision statements, can suffer greatly when written by a group. They end up sounding like long-winded supersets of incompatible viewpoints of all participants rather than concise, memorable phrases that result from forcing participants to make hard choices and accommodations [4].
CATWOE helps refine this basic definition and brings diverse views within a tolerable range. It provides a sound basis for developing purposeful activity models for subsequent action.
Elements of CATWOE
CATWOE elements are often misunderstood, partly because of how they have been formulated and because the concepts are sometimes unclear or unnecessarily restrictive. The figure shows each of these elements:
In constructing CATWOE, everything flows from the transformation. Hence, a better order to approach its elements is TWCAOE:
Transformation (T)
Transformation, T, is the means by which a defined input (current situation) is transformed into a defined output (desired situation). A common error occurs when system input (an entity that gets changed into the output) is confused with the resources that bring about the transformation. The figure below shows some good and bad examples of T:
A well-defined transformation must follow the following rules:
- T must transform I into O.
- I must be present in O but in a changed state.
- An abstract I must yield an abstract O.
- A concrete I must yield a concrete O.
Weltanschauung
The letter W originates from the German word Weltanschauung, which translates as ‘world view.’ All thinking and talking about problematical situations are conditioned by the world views of the people doing the thinking and talking.
These worldviews represent the internalized, “taken-as-given” assumptions that cause people to see and interpret the world in a particular way. For example, one observer’s ‘terrorism’ could mean another’s ‘freedom fighting.’
Worldview gives meaning to any transformation because it closely relates to participants’ perspectives. Such views can not only vary among people but can also change over time.
In CATWOE, W invokes the question: “What is the bigger picture or the environmental view of the situation, specifically of those stakeholders who can influence transformation?”
Identifying the weltanschauung implied by the transformation is the key to developing a successful model. Rather than trying to remove bias from the analysis, soft systems make it an explicit part of the analysis through the W.
Customers
Any transformation has repercussions, whether beneficial or detrimental. In CATWOE, the recipients of those repercussions are the Customers. This differs from the ‘regular’ definition of customers, which implies recipients or purchasers of goods or services.
Since implementing transformation is multi-aspectual, a single transformation can have many repercussions, each impacting different things, people, groups, etc.
For example, if the transformation is to make ferries safer by increasing their width, they may not be able to dock in some harbors (physical repercussion), passengers may not be able to sit in groups beyond 4 (social repercussion), and new laws may be enacted (juridical repercussion).
Analyzing the likely repercussions in every aspect of T helps identify a broader range of customers and know how they might be affected as victims or beneficiaries. In recent years, some SSM practitioners have made two significant changes to CATWOE [7]:
- They have replaced C with B and V, turning CATWOE into BATWOVE, where B represents beneficiaries and V represents victims.
- B and V can include ideas as well as people.
The C in CATWOE forces an aspectual analysis that avoids considering only the benefits and forgetting victims. It can even recognize the impacts on animals, plants, and physical entities as well as on people by reference to the sensory, biotic, and physical aspects.
Owners
In CATWOE, the owner, O, is a decision-maker with authority over the system and concern for its performance. The owner also bears a broader responsibility for the transformation. An Owner can change and even stop the transformation. Owners also overlap with other Actors.
Actors
Actors are the ones engaged in the transformation who perform related activities. They transform inputs into outputs.
Environment Constraints
Environmental constraints, E, are elements outside the system boundary over which the system’s decision-makers have no control or authority. These constraints must be taken as given, and activities within the system must conform to them.
Constraints can be determinative or normative. Determinative constraints are elements given by nature, such as the law of gravity and the structure of materials. A system must either adapt to them or find ways around them. Normative constraints are socially constructed and can be amended. Examples include ethos, norms, technology, resources, and objectives.
CATWOE Questions
CATWOE analysis yields a more elaborate, all-encompassing root definition of the form:
The following questions help build each element:
| C | Who are the victims or beneficiaries? (e.g. clients, residents) What are their experiences and views? Their needs and aspirations? |
| A | Who will “do the doing”, make things happen? What are their experiences and views? |
| T | What possible transformation processes are there (input to output) ? What are all the steps in the process that transforms inputs into outputs? What are the inputs, and where from? What are the outputs, and what happens to them next? |
| W | Whose worldview are we talking about? Have I tried all possibilities? What is my own worldview and what influence does it have here? |
| O | Who has the power to stop the process or situation? Could this change? Can the owner(s) help or hinder? (I try this with different possible owners) |
| E | What are the constraints e.g. funding, legislation, time, power? |
Examples of CATWOE
Shown below are examples of CATWOE applied to various systems:
Example 1: Higher Education System
| Root definition | A university-owned system run by teachers to award degrees to students who complete assessments per prescribed standards, assuring potential employers of students’ proficiency, capabilities, & skills. |
| C | Students |
| A | Teachers |
| T | Students with no degree à Students with degree |
| W | A degree is a means of assurance to potential employers that the holder possesses a specified standard of proficiency, capabilities, & skills |
| O | The university or college governing body or top management |
| E | The prescribed educational, academic, quality, assessment and accreditation standards and requirements. |
Example 2: A SaaS That Automates Marketing Processes
| Root definition | A SaaS company-owned platform that automates marketing processes for clients to improve sales outcomes. |
| C | Clients using the platform |
| A | Marketing managers, software engineers, customer support team |
| T | Manual marketing processes with low poor sales outcome à Automated marketing processes with improved sales outcome |
| W | Automation can make processes more efficient and improve sales outcomes |
| O | The SaaS company’s leadership team or senior management |
| E | Industry regulations, data privacy laws, market trends, technology advancements, client performance expectations |
Example 3: A Food Farm Targeting Higher Efficiency
| Root definition | A food farm that aims to meet customer demands through higher efficiency |
| C | Consumers who buy directly from farms. |
| A | Producers / farmers who seek to meet the consumer demand. |
| T | Less efficient processes à highly efficient processes |
| W | More quantity can be produced through efficiency without affecting quality and health |
| O | The landowner or the owner of the farm |
| E | Food norms, Rules and regulations |
Sources
1. “An Overview of the Soft Systems Methodology.” Stuart Burge, https://www.burgehugheswalsh.co.uk/Uploaded/1/Documents/Soft-Systems-Methodology.pdf. Accessed 16 May 2025.
2. “Professor Peter Checkland.” Lancaster University, https://www.lancaster.ac.uk/lums/people/peter-checkland. Accessed 12 May 2025.
3. “The Use of Soft Systems Methodology (SSM) As A Tool For Investigation.” Susan Gasson, https://www.semanticscholar.org/paper/The-Use-of-Soft-Systems-Methodology-(SSM)-As-A-Tool-Gasson/3a3271ce7b3990fdd93b083635821440d99edc33. Accessed 12 May 2025.
4. “Crafting Root Definitions and Purposeful Activity Models.” Ceri Williams, https://www.orbussoftware.com/docs/default-source/blogs/crafting-root-definitions-and-purposeful-activity-models.pdf. Accessed 15 May 2025.
5. “SOFT SYSTEMS METHODOLOGY”. The Kellogg Foundation, https://www.bobwilliams.co.nz/ewExternalFiles/ssm.pdf. Accessed 15 May 2025.
6. “Rich picture”. Wikipedia, https://en.wikipedia.org/wiki/Rich_picture. Accessed 15 May 2025.
7. “Systems Concepts in Evaluation: An Expert Anthology.” Bob Williams & Iraj Imam, https://www.amazon.com/Systems-Concepts-Evaluation-Expert-Anthology/dp/0918528216. Accessed 15 May 2025.
8. “Basic principles of SSM modeling: An examination of CATWOE from a soft perspective”. Birgitta Bergvall-Kåreborn, Anita Mirijamdotter and Andrew Basden, https://www.researchgate.net/publication/225982790_Basic_principles_of_SSM_modeling_An_examination_of_CATWOE_from_a_soft_perspective. Accessed 15 May 2025.
9. “A philosophical discussion of the root definition in soft systems thinking: An enrichment of CATWOE.” Andrew Basden and A. Trevor Wood-Harper, https://www.researchgate.net/publication/28579152_A_philosophical_discussion_of_the_root_definition_in_soft_systems_thinking_An_enrichment_of_CATWOE. Accessed 15 May 2025.