What is a logical “long arrow”?

In Logical Thinking Process (LTP) parlance a long arrow is a “leap of logic” or the omission of one or several cause-and-effect steps that connect a cause to an effect.

In the Logical Thinking Process, a cause is linked to its effect by an arrow. The arrow’s tail is connected to the cause and the tip points to the effect. Hence the reference to the arrow.

In the picture, the cause is at the bottom and the effect is on the top.

Ellipses are logical “AND” connectors. Arrows going through an ellipse read “if…. AND if… then…”

Some may refer to the AND connectors as “bananas” but I would not encourage this.

The “long arrow” skips several “if…then…” or cause-and-effect relationships, also considered as logical steps.

Leaps of logic are to be avoided for the sake of logical soundness. Long arrows are likely to confuse an audience as the listeners or readers cannot naturally link the things together.

True listeners may have difficulties to follow the speaker’s logic or readers might get confused, lost or perplexed while reading a text.

Many people speak or write long arrows because the sequence of causes-and-effects is clear in their mind. They don’t pay enough attention how their thinking can be received by someone not knowing about the subject, the unspoken assumptions or the implicit and skipped relationships.

The more logical steps or cause-and-effect links skipped between a specific cause and an certain effect and the longer the arrow.

In the scrutinization process of logic trees, long arrows are generally considered as “mistakes” or at least “logical improvement points”. Long arrows are not officially considered as Categories of Legitimate Reservations (CLR), but could in fact. Long arrows should be broken into more detailed steps in order to get the faulty tree more sound and robust from the Logical Thinking Process point of view.

About the author, Chris HOHMANN

About the author, Chris HOHMANN

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Why you cannot use tentative language in a logic tree

I once happen to see a Current Reality Tree cluttered with “coulds” and “shoulds”. Conditional or tentative language cannot be used with logic trees and here is why.

Cause-and-effect (sufficiency logic)

The Logical Thinking Process logic trees use either sufficiency or necessity logic. Sufficiency or cause-and-effect relationship states that a cause, if it exists, is sufficient by itself for the effect to happen. Using conditionals like should or could violates the sufficiency principle as it suggests that the cause is not always producing the effect.

The Current Reality Tree (CRT), Future Reality Tree (FRT) and Transition Tree (TT) are built on sufficiency logic and therefore cannot hold any entity with shoulds or coulds.

If a should or could is found in such a tree, the scrutinizer must raise a “cause insufficiency reservation“. The statement must then be corrected, for example by adding one or more additional cause(s) combining to the first one with a logical AND connector. If this combination is valid, the sufficiency relationship is restored and should or could is removed as the effect is now guaranteed to happen.

If no additional causes can combine to the first one, the cause-and-effect relationship is probably only assumed or false. Anyway no should or could can be left in a logically sound tree.

Using present tense

The entities – the building blocks of the logic trees holding the statements – must be expressed in present tense.

Using present tense is natural in a Current Reality Tree (CRT) as it is the description of the actual situation, the cause-and-effects relationships that exist right now.

The use of present tense in Future Reality Trees (FRT) is highly recommended even so these future situations and the Desirable Effects do not yet exist. Present tense helps to project oneself and the audience into the future and visualize the situation as it were already improved (Scheinkopf, “Thinking for a change, putting the TOC Thinking Processes to use”, p119). Dettmer also recommends to use positive wording (Dettmer, The Logical Thinking Process, p244).

This applies to entities in a CRT, a FRT and in a Prerequisite Tree (PRT) which are verbalized in full sentences.

What about necessity-based logic?

Can necessity logic based tree use conditional/ tentative language?

The Goal Tree (GT), the Evaporating Cloud (EC) and Prerequisite Tree (PRT) are built on necessity logic. They describe the chains of enabling conditions that are required to achieve a goal or an objective. Without the enabling conditions, the objective cannot be attained. Conversely, with the enabling, necessary conditions fulfilled, the objective will not automatically be achieved; additional action is required.

As the Desired Effect is not guaranteed to happen even so all necessary conditions are fulfilled, the use of conditional / tentative language seems legit. Practitioners would not use it though.

First because we need to demonstrate positivity about a desirable change and help the audience to mentally visualize the future where things happen and produce the desired outcome.

Second because we need to give confidence and demonstrate our own trust in the proposed solution. No audience would be thrilled hearing that this solution “may”, “should” or “could” produce the desired result. No decision maker would give his/her go for a change program or a solution implementation which is not certain to produce the expected result.

The use of conditional / tentative language would only raise concern about the feasibility of the proposed solution and appear as a lack of confidence of its promoters.

Wrapping up

Tentative language is recommended in academic writing, not at all with logic trees.

Using tentative language is recommended in academic writing and scientific research in order to leave room for alternatives, later corrections, etc. unless there is solid evidence backing up a statement. Therefore the use of verbs like “appear, suggest, indicate,…”, modals “may, might, can, could, will, would” and adverbs like “possibly, probably, likely…” are recommended.

But when building or presenting logic trees, absolute certainty is required in order to demonstrate robustness of the analysis and the confidence in the conclusions. If a logic tree is built on the canonical logic rules (we’ll consider the use of present tense as a canonical logic rule), has been scrutinized and cleared of all reservations, it is robust and tentative language is no option.

The author, Chris HOHMANN

The author, Chris HOHMANN

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The Logical Thinking Process – An Executive Summary (Book)

Bill Dettmer, my friend and mentor often cited on this blog, wrote his 9th book “The Logical Thinking Process – An Executive Summary” that is now in the final stages of the publishing process.

This book will be much smaller in size and number of pages than the famous “The Logical Thinking Process: A Systems Approach to Complex Problem Solving”. The latter is a 413 pages, 17,1 x 3,2 x 24,1 cm (6.8 x 1.2 x 9.5 inches) hardcover book. Bill Dettmer’s students use to call it “The Bible”. It is a complete step-by-step guide, easy to read and understand, but not everybody can invest the time required to read it just to get a primer on the Logical Thinking Process.

That’s where the “Executive Summary” comes in handy. Bill himself stated: “Over the years, I’ve found myself having to explain what the Logical Thinking Process is in 30 seconds or so to people who have never heard of it – or know nothing about it if they have. I came to the conclusion that while the LTP is difficult, if not impossible, to encapsulate in an “elevator speech,” it might be somewhat easier to do in a pocket-sized book.

I was fortunate to be selected by Bill as a kind of sounding board and proofreader, even so Bill did so more out of kindness than necessity, and had a privileged first reading. The book will serve its purpose, I think it can be read during a short business trip on a plane or a train. The final copy should be less than 100 pages.

As soon as I’ll get a copy, I will complete this post with an extended review of the book.

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Goal Tree Chronicles – Coloring the Goal Tree

The 3-colors system is a well accepted assessment and visual management tool by Goal Tree builders and users. The principle is simple as it uses the traditional Red-Amber-Green color code to indicate the status of each entity in the Tree.

In a Goal Tree, Necessary Conditions are enablers to the above entity. As soon as enablers are not in place or “unstable”, the outcome they should enable cannot be considered as in place, delivering or achieved.

In this post, I detail how to color a Goal Tree.

How to color a Goal Tree?

Start at the bottom, with the very basic Necessary Conditions. Have the Subject Matter Experts (SMEs) assess each Necessary Condition for its status. As soon as a basic Necessary Condition, which is a requirement or prerequisite to the above entity to exist, is Amber or Red, the above entity can only be Amber or Red. The color, symbol for the status, propagates upwards like in a line of dominos when the falling one pushes the next.

Goal Tree

Reminder: in “my” 3 color system, green stands for granted, constantly available, steady… Amber means unstable, not totally fulfilled, variable… Red means missing, non-existent, not at nominal value, etc.

Therefore, the assessment can be quite quick. The SMEs should know what’s going on on shopfloor, how process behave and deliver. Key Performance Indicators (KPI) may give additional information.

In a starting project, chances are that many identified basic requirements are not yet fulfilled, so their boxes in the Goal Tree are red. As soon as such an entity turns Amber or Red, no need to assess the above related entities, they are Amber or Red by definition.

Related: Goal Tree: How green is your tree?

The requirements that are Green need to be followed upwards nevertheless to see if their above related entities are Green as well, or if an additional Necessary Condition coming in sideways has a non-Green status. If this is the case, the above entity takes the color of the worst of the underlying Necessary Conditions’ color.

The limits of the 3-color system

It can happen that despite an entity having all its underlying Necessary Conditions set to Green can’t be assessed as Green. Facts and figures just don’t allow it. How come?

Well, remember: underlying Necessary Conditions are enablers, not triggers. Unlikely what happens with sufficiency logic where a cause is literally sufficient to produce the effect, the necessity logic used in the Goal Tree states that if a Necessary Condition is missing, the expected effect can not happen, but conversely, the underlying Necessary Condition existence is only enabling the effect to happen.

Entities in a Goal Tree are also called Intermediate Objectives and in order to achieve an objective, 3 conditions are required: having the necessary means to achieve the objective, knowing how to achieve it and being motivated to achieve it.

Related: What it takes to achieve your objective: Means, Method and Motivation

In case a should-be green Intermediate Objectives isn’t green, you should check the Means, Method and Motivation.

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About the author, Chris HOHMANN

About the author, Chris HOHMANN

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Goal Tree Chronicles – Enablers vs.triggers

In this post I explain the difference between enablers and triggers in logic trees, which basically is explaining how Necessity logic differs from Sufficiency logic. I then explain the basic assumption when building a Goal Tree and why the Goal will not automatically be achieved even if a most of Necessary Conditions are fulfilled.

Necessity vs. sufficiency

Necessity-based logic requires a prerequisite to be fulfilled in order to produce the expected effect. This is why necessity-based logic uses “in order to… [effect] we must … [prerequisite]” wording in the Logical Thinking Process.

Example: in order to have my hair cut, I must go to the hairdresser.

Even so there are alternatives to the hairdresser to have the hair cut, a prerequisite is necessary for the hair being cut.

Sufficiency, as its name suggests, does only require the cause to exist for the effect to automatically exist. The corresponding wording is ”if…[cause] then.. [effect].”

Example: if it rains, then the lawn gets wet. Or if I drop an ice-cube in hot water (the) it melts. In these examples there is little that can be done to prevent the effect to automatically happen when the cause happens.

Enablers vs.triggers

I assume dear readers, you understand the huge difference between Necessity and Sufficiency. While an effect will automatically happen if the cause exists in the case of sufficiency, the existence of the prerequisite (cause) in necessity-based logic is not enough to produce the effect, it only enables it.

For example, many prerequisites are necessary to build a house, like having a ground, having timber, having a permit, and so on. But having all prerequisite will not lead the house to build itself.

In sufficiency logic, the cause is the trigger while with necessity logic, the cause is “only” an enabler.

The Goal Tree is built on necessity-logic

The Goal Tree, one of my favorite logic tools, is built on layers of Necessary Conditions, linked from the Goal on the top to the very first Necessary Conditions at the bottom by necessity-logic. The convenient way to build a Goal Tree and scrutinize it is to check the sound logical relationship between an entity and the underlying Necessary Condition using the “in order to… [effect] we must … [prerequisite]” phrasing.

The logic trees and cloud from the Logical Thinking Process are either necessity-based or sufficiency-based and in the order of their sequential usage they alternate between necessity and sufficiency.

Now because the Goal Tree is built on necessity logic, the entities composing it are absolutely necessary to exist or being granted for to achieve the Goal. By definition, if one Necessary Condition is not fulfilled, the Goal cannot be achieved.

But, as Necessary Conditions are “only” enablers, nothing will happen as long as no real action is taken.

Achieving the Goal

Achieving the Goal requires all Necessary Conditions or enabling prerequisites to be fulfilled, but it is not sufficient.

This can be disturbing for those being exposed first time to the Goal Tree, because there is an implicit assumption that when the enablers are in place, the necessary actions or decisions will be taken, so that from bottom to top, all Necessary Conditions are fulfilled and the Goal eventually achieved.

Promoters, including me, tend to cut corners and advertise about the lower level Necessary Conditions “automatically” turn the upper ones to be fulfilled, and the achievement of intermediate objectives to happen like a row of dominoes propagating the fall of the first one till the very last: the system’s goal.

This is true if people in charge do their part: take the decisions and/or carry out the tasks.

This is why, “surprisingly”, some entities can be Amber or Red (condition not always / not fulfilled) even so their underlying Necessary Conditions are Green (condition always fulfilled).

If you are not yet familiar with my 3-color system, I suggest you read: 3-color system for Goal Trees


Here is such an example. It comes from an operational Goal Tree built to enumerate all Necessary Conditions to pass over simple maintenance tasks from maintenance technicians to line operators. The simple tasks include daily lubrication and check of tightenings in order to prevent wear and possible breakdowns. The aim is to implement the Total Productive Maintenance ‘Autonomous Maintenance‘ pillar.

Once all Necessary Conditions are listed, the Goal Tree is scrutinized for robustness and if ok, it becomes the benchmark to achieve the Goal. The next step is to assess each Necessary Conditions for its status.

We see in the figure above (showing only a tiny part of the Goal Tree) that all underlying Necessary Conditions to “Daily lubrication / tightening is done” are Green, but the expected outcome, the effect is Amber. Since every prerequisite is Green, we expect the effect to be Green as well. Amber means the outcome is not stable, not always guaranteed, not steadily at nominal level.

It means this expected outcome, the task “daily lubrication / tightening is done”  is NOT done EVERY day.

One may argue that we cannot see any mention of the lubrication / tightening being part of operators’ duties. That’s correct. The reason for this is that in logic trees, obvious prerequisites or assumptions are voluntarily omitted for the sake of keeping the logic trees simple and legible. In our case, the work instructions include the daily lubrication and tightening routine. This is a known fact for everyone concerned with this Goal Tree.

In other words, enablers are ok, but the trigger is still missing.

It is now up to management to:

  • make sure operators have a full understanding of the work instructions,
  • make sure these tasks are carried out and
  • clarify what is to be done if operators face a dilemma like catch up late work or go as planned for maintenance routine.

Fortunately those cases are the exception. People truly involved in a project and having a clear understanding of the purpose will contribute. That is, as long as they are not exposed to undesirable effects, from their point of view.

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Industry 4.0 promoter’s flaw of logic and Categories of Legitimate Reservation

Promoters of any solution or change agents of are usually in love with the object of their promotion. Love is said to be blind and oblivious of any negative aspect of the loved thing. That is why so often promoters of change highlight all the benefits of the change, regardless of any Undesirable side Effects for the people they try to convince to change. They usually also complain about resistance to change when skeptic listeners do not show enthusiasm for the promoted brilliant solution.

But promoters may also forget to adapt their communication to the targeted audience. They may know well their subject and cut corners, leaving the audience with doubts and questions about a logic they can’t completely follow.

In this post I will address:

For that I pick two sentences from an Industry 4.0 promoter’s blog post which does not seem logically sound.

The statement

“Brave companies who adopt new approaches (e.i. Industry 4.0) and adapt how they manufacture and run their businesses will be rewarded with success. While those who drag their feet and avoid risk will get left behind.”

There is no further explanation in the blog to backup these two sentences.

The first sentence, rephrased in logical cause-and-relationship reads: “if companies adopt new approaches (e.i. Industry 4.0) AND if companies adapt how they manufacture and run their businesses THEN companies will be rewarded by success.”

The AND here suggest that the two conditions must be fulfilled simultaneously in order to cause the success.

Necessity-based logic versus sufficiency-based logic

The statement is made with sufficiency-based logic, because it suggest that the adoption of new approaches and adaptation are sufficient to cause the companies to be successful.

Sufficiency is base on “if…then” or cause-and-effect relationship.

If the article was about listing all the conditions necessary to make the companies successful, it would have been necessity-based logic. In this case the relationship would have been: “in order to… the companies must…”.

The logical structure that Logical Thinking Process aware people “see” in the statement is either a Communication Current Reality Tree or a Future Reality Tree.

To learn more about necessity-based logic versus sufficiency-based logic, check my post: Goal Tree Chronicles – Enablers vs.triggers


1 – Clarity

The first reservation about this statement is a clarity reservation about the meaning of “success”. What is “success”? How can we measure it? How can we know whether the company is “successful” or not?

Unfortunately there is no way to ask the author for clarification. One could understand that deployment of industry 4.0 technologie(s) together with adaptation of the work procedures is a success. A project manager in charge of such a program would surely agree about this definition of success.

The CEO and the board are probably looking for more than having the latest technologies installed, even it probably helps the image of the company to have a nice techno-showcase. In their view, success is more likely increase of sales, profit and market share. Let’s assume this one is meant by “success”.

We could go on and challenge the meaning of “new approaches”, “industry 4.0” or even what is exactly meant by “how they manufacture”. In case someone really need clarification, the question could be raised, otherwise let’s not go for unnecessary wordsmithing.

2 – Entity existence

An entity in the Logical Thinking Process parlance is a statement that conveys an idea. An entity is also the logical box holding the statement in the various logic trees.

An entity must only convey a single idea, therefore when building a logic tree on this statement we must have 3 entities combining their effects to produce one outcome: the success of the companies (read figure from bottom to top).

3 – Causality existence

Causality existence is checking the existence of the causal connection between entities.

“if companies adopt Industry 4.0 AND if companies adapt how they manufacture AND if companies adapt how they run their businesses THEN companies will be rewarded by success.”

Does it exist? One example would be enough to demonstrate it exists, but, in absence of hard evidence, the likeliness of the causality existence must be evaluated. We assume it’s ok.

4 – Cause sufficiency

Are the 3 proposed causes sufficient alone to produce the effect “successful companies”? I would intuitively say no. There is a lot more necessary. We are here facing a typical “long arrow” which is a leap of logic from some causes directly to the outcome, ignoring intermediate steps and conditions in between.

This is typical when people discuss matters they know well because they don’t have to detail everything, they know what is missing and is implicit. But here it is about promoting something which is quite new (in 2017), relatively complicated and not very well-known by laymen. Effort should be paid to elaborate on the message in order to favor buy-in.

5 – Additional cause

This check is looking for other causes that can independently produce the same effect. There are indeed other ways for companies to be successful than going for industry 4.0, but the statement suggests there is only one, as it warns: “those who drag their feet and avoid risk will get left behind.”


With these two last reservations we uncover the major flaw in the statement:

  • The proposed “logic” is not likely to be enough to produce the expected effect
  • There are other ways to be successful

From the audience point of view, the argumentation is weak. This is more likely to raise suspicion about the promoter’s expertise and trustworthiness, thus distrust and reservation than frantic enthusiasm about the proposed idea.

Such a weak argumentation can have devastating effects, making decision makers to turn their backs, refusing a good plan or a clever strategy which was ill-prepared and badly presented.

The Categories of Legitimate Reservation are 8 formal “rules” or “tests” used to check the logical soundness of a reasoning or an argumentation. They are part of the Logical Thinking Process corpus.

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Reader question: Goal Tree vs. Current Reality Tree

Here is a reader’s question: I have difficulty seeing the difference between the Goal Tree and the  Current Reality Tree (CRT). With these two trees we assess the process. What are the main differences between the two?

The Goal Tree and Current Reality Tree (CRT) have nothing in common. They are not even meant to care about processes but about the system as a whole. Neither the Goal Tree nor the CRT are process maps.

>Lisez-moi en français

A Goal Tree lists all Necessary Conditions to achieve a Goal, which is not yet achieved, so it is about the future.

The CRT describes why the Goal is not yet achieved in the current state. It starts with identified Undesirable Effects (undesirable for the system as a whole) and drills down to the few critical root causes.

A Goal Tree is built from top-to-bottom with necessity logic while the Current Reality Tree (CRT) is built from top-to-bottom using sufficiency logic. This building top-to-bottom is maybe the sole commonality between the two.

To learn more about the differences between necessity and sufficiency logic, check out my post: Goal Tree Chronicles – Enablers vs.triggers

The name Current Reality Tree is somewhat misleading because the CRT is limited to the description of the negative outcomes. It does not describe all the Current Reality. This is saving a lot of unnecessary analysis as well as a warning to not mess with what is currently producing Desired Effects!

What could have caused some confusion to my reader is the fact that a Goal Tree is a benchmark against which to measure the gaps in current reality.

When doing this I use a 3-color code to indicate each Necessary Conditions status. I assess the current condition of the system with the Goal Tree as benchmark. The first autumnal-colored tree should be kept as is as a snapshot of the situation at the beginning. Distinct trees are used later to monitor the progress of ‘greening’ the tree, i.e. closing the gaps to achieve the Goal.

I hope this helps to understand the differences between a Goal Tree and a Current Reality Tree.

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Scrutinizing and improving a Current Reality Tree (video tutorial)

In this video, I scrutinize and suggest improvements on a Current Reality Tree (CRT) found on the Internet. A logically sound CRT is key to convince audience about the robustness of the analysis and the reality of the causes to the trouble. If there is room for doubt or the logical has flaws, chances are that the audience will not buy-in, especially those having some “skin in the game”…

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