Limits of Logical Thinking Process

In this excerpt of day one from the 6-day Logical Thinking Process training course, Bill Dettmer explains that the very front end, the two first tools (Goal Tree and Current Reality Tree) are deterministic, based on facts. The other steps and tools are about future, which can only be based on probabilities.

At the end of this short video, Bill gives his definition of the Logical Thinking Process.

Bill Dettmer refining some points about Logical Thinking Process

In this video, an excerpt of Bill Dettmer‘s Logical Thinking Process (LTP) training course in Paris, June 2015, Bill refines some points about LTP.

First, the two first tools (Trees) of the LTP, namely the Goal Tree (GT) and Current Reality Tree (CRT) are based on facts. The others, Evaporating Cloud (EC), Future Reality Tree (FRT), Prerequisite Tree (PRT) are based on high probability things will happen as planned.

The components of a Goal Tree, called Necessary Conditions (or NCs) are factual needs necessary to achieve the Goal. The Current Reality is described in a CRT in a way that can be checked and proven, based on facts.

As soon as the people are working on the future, from Evaporating Cloud on, it can only be described in probabilities, as things may not exactly turn out as planned. Theory of Constraints’ Logical Thinking Process may need to rely on other tools and methods than Negative Branch Reservation (NBR) to mitigate the risks.

Furthermore, the time to accomplish the necessary tasks is an evaluation at best.

Finally Bill summarizes what Logical Thinking Process is:

a structured way to move from an ill-defined system level problem to a fully implemented solution.

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Rotate a Tree to start your project

During the Logical Thinking Process training course (June 2015), Bill Dettmer took us through the whole process and the associated tools at each step.

The process starts with the famous Goal Tree, assess the current situation and focus on critical root causes with the Current Reality Tree (CRT). Conflict Resolution Diagram (AKA Evaporating Cloud) may be used to resolve conflicting objectives and find solutions (called “injections”) to turn the CRT into a Future Reality Tree (FRT).
But in order to get to the future state, some obstacles will have to be removed or by-passed. This is done with the help of a Prerequisite Tree (PRT).

Once the PRT is ready, it is a kind of logical proof of concept. In order to turn this POC into real action, Bill shows how rotating a Prerequisite Tree gives an almost ready-to-use project network. Therefore, Critical Chain Project Management (CCPM) is the sixth tool of the Logical Thinking Process.

By the end of the demonstration, Philip Marris highlights the “beauty” of this process, patching one of Critical Chain Project Management “weaknesses”: how to ensure what is to be executed as a project is meaningful? He does this by giving a sadly funny and true example in aeronautic industry.

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Logical Thinking Process

LTPThe Logical Thinking Process refers to the work of William (Bill) Dettmer summarized in the book of the same title. The Logical Thinking Process (LTP) is a one to six steps* process using sound logic and a set of tools (or processes) to provide executives and system managers an effective method for designing organizational strategy, planning its deployment, evaluating its effectiveness, and making corrections as needed in the shortest possible time.

Bill Dettmer & Chris Hohmann

Bill Dettmer & Chris Hohmann

*the number of steps required or used may vary by necessity or choice/experience of the practitioners

It starts with the Goal statement, the Vision or what the Lean community refers to as “True North”. The Goal can be set only by those who created the system, the system owners or those having the responsibility to conduct the organization toward the Goal set by the founders.

The Goal is dependent upon a series of Necessary Conditions, among which some high level terminal outcome are called Critical Success factors. The visual representation from the Goal down to Necessary Conditions forms the Goal Tree.

The Goal Tree is a benchmark but the actual condition of the organization may not be the one required.Thus the Goal Tree gives input to the next tool in the Logical Thinking Process: the Current Reality Tree (CRT).

With the CRT, the organization is assessed or “audited” about gaps between the Goal Tree requirements and the actual condition. Gaps lead to Undesirable Effects or UDEs. These UDEs are the inputs for the next tool: the Future Reality Tree (FRT) in which the UDEs are neutralized with “injections”; causes or conditions not yet existing and designed to turn UDEs into their opposites: Desirable Effects (DEs), without bringing negative side effects.

Logical Thinking Process
Between CRT and FRT is another tool, called Evaporating Cloud (EC) or Conflict Resolution Diagram (CRD). It is specifically used to solve conflicts, like going for small batches wanted by sales and going for big batches wanted by production, for example. Each party has good reasons to demand for what they see as being the best, but usually the conflict is based on false assumptions the EC helps to surface and then “evaporate” the conflict.

The Prerequisite Tree (PRT) is the next tool of the LTP. It is used when stakeholders argue about obstacles to implement the solutions found with the FRT and EC. Every obstacle is then neutralized or by-passed with Intermediate Objectives (IOs), smaller necessary steps and conditions to fulfill in order to bypass the obstacles.

Finally the Transition Tree (TT) is a kind of detailed action plan but still at system level. Actions, combined with the actual reality and the needed condition lead to the desired new reality and closer to the Goal.

Rational, logic, robust

All the Trees and the Cloud are based on logical relationships between their entities, which makes them as well as the whole process unbiased of beliefs, false assumptions, emotional and irrational choices, and filter out irrelevant or unnecessary “nice-to-haves”.

The result, if correctly built, is a very robust and complete roadmap to the next level towards the organization’s goal.

The various tools, especially Goal Tree, Current Reality Tree, Evaporating Cloud and Future Reality Tree may be used as stand-alones or in combination. When rolling out the whole Logical Thinking Process, the work group may stop when the FRT is complete and checked, as they feel no need to get into more details with the next trees.


Don’t be afraid by all the metaphoric jargon, it must be learnt but is not that hard. All the available body of knowledge relies on this jargon and it’s the Theory of Constraints community lingo. No way to do without it, like it or not.

Thinking Processes versus Logical Thinking Process

There is a subtle difference between Thinking Processes – plural – and (Logical) Thinking Process – singular.

  • The Thinking Processes refer to the five tools, four trees and one cloud, from CRT to TT and do generally not include the Goal Tree.
  • The Logical Thinking Process is the process described previously, using the same tools plus the Goal Tree. Bill Dettmer keeps considering the trees and cloud as tools, not as processes and sees only one overall process.

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A perfect world is a lovely place


Chris HOHMANN – Author

It happened during a project review meeting during which we went through the planned action sequences. A new late comer to the project raised a few questions and suggested some additions and changes to the action plan.

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One of the participants, visibly irritated by the new entrant and his interventions, snapped back: “A perfect world is a lovely place, but we need to focus on our goal without seeking perfection.”

He was referring to the constraints and difficulties limiting our possibilities and options and obviously trying to silence the newcomer.

As moderator of this meeting I calmly explained that at this stage of the project, any suggestion that contributes to its robustness is welcome. Furthermore, a description of perfection is always interesting.

Indeed, the ideal or perfect solution may be out of reach for the moment, but this does not mean that all options must be rejected. An evolution of the strategy, economic conditions, regulatory, state of mind of the decision makers or technology can reshuffle the cards and open the field of possibilities.

In such a case, having a complete description of an ideal future state can be a big time saver. In addition, the ideal solution is a reservoir of ideas for future improvement and it makes sense to revisit these options periodically. One or the other constraints could disappear and new options become possible.

Generally speaking, an ideal future state can always be degraded by incorporating the various constraints, but building a solution around existing constraints without exploring breakthrough alternatives typically falls within the 8th type of Lean waste: not using people’s creativity.

The meeting resumed in a little tense atmosphere due to the enmity between the two individuals, but with the new suggestions taken into account.

When it comes to Value Stream Mapping (VSM) and sketching the future improved state (Value Stream Design or VSD), the above explanation applies perfectly.

It makes sense to study the ideal target first and then to degrade it by integrating the different constraints that may not be eliminated or bypassed in reasonable time or cost.

Those readers familiar with the Thinking Processes of the Theory of Constraints certainly try to challenge the reality of the constraints with specific tools like the Current Reality Tree (CRT) and the Conflict Resolution Diagram (CRD, aka Evaporating Cloud).

At the time of this meeting, I used a Goal Tree previously built with the participants but couldn’t investigate and challenge the constraints.
It is very likely that among the listed constraints, some are more a matter of beliefs, myths and misunderstandings or misinterpretations than real constraints.

If these false constraints can be surfaced and eliminated, the solution will certainly be better and it will prove the value of exploring the ideal state before giving up too soon.

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Thermodynamics of Eternity or Current Reality Tree in Hell

Paris, November 2014, Bill Dettmer was guest of Marris Consulting. I was fortunate to be among the guests for videotaping interviews.

In the following video, Bill introduces the Current Reality Tree, first of the Thinking Processes tools, with an uncommon example.

>Previous video: Video interviews with Bill Dettmer: LTP training participant’s testimony

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Video interviews with Bill Dettmer: LTP training participant’s testimony

Erik Mano co-Director of Marco Tech and Philip Marris CEO of Marris Consulting discuss Bill Dettmer’s Logical Thinking Process.

Erik Mano describes how he became interested in The Logical Thinking Process (LTP): his ambition to improve the performance of his company. Discovering Eliyahu Goldratt’s business novel “The Goal” and the hidden thinking processes it this book, reading Bill Dettmer’s book “The Logical Thinking Process” and then participating in Bill’s 6 day training workshop, applying LTP to his company and finally developing the habit of using LTP as an everyday reflex.

He comments on: the “Goal Tree”, the “Current Reality Tree”, the visual aspect of “trees” to explain and convince people and the “Evaporating Cloud” conflict resolution tool.

A quote:

By identifying your goal and where you stand today, you see the gap and you can get everyone to agree on the gap. Just doing this means you have reached quite a good level in your organization.

Filmed in Paris in November 2014. Video production by Christian Hohmann. Erik Mano was a guest of Marris Consulting.

>Previous video >Next video

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Meeting Bill Dettmer

I am fortunate having met William Dettmer in Paris, France, November 27 and 28th, 2014.

Bill is senior partner with Goal Systems International and author of eight books and numerous articles about Theory of Constraints, Thinking Processes and more.

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I have read Bill’s works and found myself deep-diving with great intellectual pleasure into Goal Trees, Current Reality Trees, Conflict Resolution Diagrams and more. It helped me a lot getting familiar with the Thinking Processes.

Having the opportunity to meet, chat and listen to the author in my hometown is a rare privilege I enjoyed very much.

Bill was guest of Philip Marris, the leading authority of Theory of Constraints in France, in his Paris office. Philip invited me too, challenging me with video recording and editing the meeting for an online series of videos.

Hohmann, Dettmer, Mano

These two days were great fun, sometimes for the talents in front of the cameras watching me running around the setup to check, fix or start a device, sometimes for all when the inevitable bloopers forced to restart the take.

While monitoring the recordings, I learnt a lot listening to Bill’s explanations and stories. He is not only an expert with long experience, he’s also a great storyteller.

These last points were endorsed by Erik Mano, the third guest of Marris Consulting, who attended Bill’s course in Luxembourg some time ago and testified about the course, its content and the usage he made of the Thinking Processes.

Dettmer and Hohmann

While these two days were fairly high-density, we found moments to relax. Philip suggested a picture of Bill and me sitting side by side with our books in front of us.

Regarding the number of books, Bill won (8 to 4) but admitted to the fact of being few years younger, I still can catch up.

But what I will never be good at is smiling.

Watch the first video introducing a serie about the Logical Thinking Process

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Thinking Processes – Current Reality Tree

The Current Reality Tree (CRT) is one of the Thinking Processes logical tools. As the name tells, it depicts the current reality* in a series of dependent logical cause-and-effect relationships, starting from Undesirable Effects down to one or a few critical root causes.

A root cause may also be called “core problem” or “core driver” in the original concept.

*Current Reality is somewhat misleading as it is focused onto the negative outcomes and what prevents achieving the Goal in order to solve problem and improve the situation. Besides, the Current Reality depicted in a CRT is a snapshot at a given moment.

Undesirable Effects (UDEs) are often called “problems” that people perceive, suffer from or have to cope with, but UDEs are most often only symptoms of deeper laying problems. The CRT is a tool that helps to surface and address the critical root cause(s).

As for many elaborated problem solving methods and tools, building a CRT is not required for every problem. It was specifically designed to solve complex, multi-factor and system-wide problems.

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Reading a CRT

It takes some experience to build a robust Current Reality Tree, which should not be done by a single person by the way (for the sake of robustness), and the best is to get used to read them first.

Current Reality TreeA CRT has more or less a V shape with the topmost and numerous UDEs on the top, other UDEs that are causes from topmost UDEs and their own causes, and so on down to the few critical root causes, usually located (near or) on the base of the CRT.

Once a tree is completed, it can be read either top-down or bottom-up. The construction is always top-down, from symptoms to causes to critical root causes.

A CRT is made of entities which are round-cornered boxes holding a brief description of a fact in present tense. Entities are either causes or consequences and most of them are both.

Entities which are linked have an arrow between them. The base of the arrow reads “if…” and the tip reads “then…”.

When reading a CRT top-down, the succession of linked entities reads “entity B exists (tip of arrow points to it) because of entity A (arrow starts from it)”.

When two or more arrows point to an entity, the entities at the base of the arrows are possible causes. The different arrows are logical “inclusive OR” relationships.

When the arrows are encircled by an ellipse, it means logical “AND” relationship: all the causes must exist simultaneously for the effect to exist.

Theory of Constraints is about focusing and leveraging, so does the CRT. The purpose of a CRT is to search for the root cause and while eliminating it, the whole tree of dependent UDEs disappears.

The investment of analyzing the situation with a CRT is really worth it, compared to the useless and wasted efforts trying to solve all the UDEs. Concentrating efforts on the sole critical root causes is much more efficient.

CRT example

CRTHere is one half fictitious example of a CRT inspired by a company I worked with.

The V shape is not so obvious (due to page / screen width limitation) but even without reading the entities, you’ll notice a node at the bottom of the CRT, which is a graphical hint for a good candidate of a core problem.

Indeed, in this case, all UDEs can be linked to the fact that over time, this company let its leadership slip away and now is facing tough competition with commonplace products.

As margins plummet, means for new developments are scarce and the fear of competition leads the company to follow the leaders, reinforcing its commonplace products offers.

Besides, having no clear company strategy, managers define themselves objectives without any alignment, which leads to many wastes in operations (see amplifying loop).

If the company manages to get out of commonplace products and regain leadership, the UDEs should disappear.


Please consider this post only as a brief introduction to Current Reality Tree. It takes some know-how and experience to be able to build a sound and robust CRT.

>Other example: Thermodynamics of Eternity or Current Reality Tree in Hell, a video with Bill Dettmer


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Bending the Current Reality Tree

The Current Reality Tree (CRT) is one of the Theory of Constraints (ToC) Thinking Processes (TP) tools. A CRT is built on Undesirable Effects (UDEs) linked by logical cause-effect-cause relationship called “sufficiency”. Sufficiency logic relationship is in the form of “if A is true then B is true”, or “if A exists, then B exists”.

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A CRT describes the reality, lists the issues that hinders the system / organization to have better throughput.

Building a CRT in the orthodoxical way follows strict rules and good practices. Among the good practices is the one that recommends the CRT has to be built with all stakeholders and then checked for “legitimate reservation”.

I used the CRT in an unorthodox way once during an assignment, thus this post title “bending the Current Reality Tree”.

It was during a quite strange and difficult assignment in which we couldn’t get the organisation chart nor key figures but had to find out the causes of all troubles and recommend solutions nevertheless. The CEO was against the consultants, but the COO could made him agree to let us make a pre-diagnosis.

Puzzled about how to go on, I had an intuition during the managers’ interviews: write down all UDEs they would mention and try to build a CRT afterwards.

The interviews were one manager a time and we had no opportunity to have a CRT building workshop with all of them.

I collected 347 UDEs of all kind and started to sort them out in relevant categories. This sorting led to 23 categories holding all the UDEs.

Then, instead of trying to combine all the UDEs in a single tree, I built trees according to how UDEs formed links between themselves and ended up with 6 trees on following topics:

  1. Management
  2. Information Technologies
  3. Marketing
  4. R&D
  5. Overall performance
  6. Misc.

These trees helped me and my team to structure the results of the interviews and analysis. CRTs are great tools to describe the current situation as they “tell the story”.

We used the posters with the trees to debrief top management. These posters were no artwork, not very nice made: the paper sheet was the paperboard’s or brown paper and each UDE was a strip of paper printed out from my Excel file I used to order the UDEs. Nevertheless, their value was in the content, not the design.

The posters were pinned on the wall and the audience could freely walk around to read the content. People were glad to see their verbatim captured and taken into account, in an anonymous way, ordered and displayed in a logical arrangement they could understand and agree.


The deviations vs. CRT building:

  • no preparatory boundaries check e.g. what is in the scope, what influence a manager have on the UDEs..
  • building the tree alone after UDEs’ collecting, not in group with stakeholders, thus the trees reflected only the consultant’s point of view and understanding
  • no validity check via Categories of Legitimate Reservation
  • no cross reading except with my colleagues
  • did not use round corner boxes

What was complying to the CRT building methodology:

  • UDE clarity check. I sometimes rephrased the original stance to disambiguate or for the sake of clarity. Clarity was also checked with my colleagues
  • Sufficiency logic check, UDEs were only linked if the sufficiency condition was met

This somewhat unorthodox use of the CRT helped us to better understand the causes of the overall situation and to feed it back to the company’s management. Our audience had no problem with the deviation as they did not know about CRTs anyway.

The assignment did not get further than this pre-diagnosis. Our trees were left at client’s, up to managers to reuse them. If the assignment would have continued and led to an improvement project, it is probable that the trees would have been used as CRTs to work out Future Reality Trees, this time in a more conventional way; in workgroups.

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