As with most of simple looking methods and tools, it is easy to get trapped or misuse the seemingly simple logical tools proposed by the Thinking Processes. In order to prevent decision making and actions based on flawed analysis, the CLR provide effective rules to check and validate the logical soundness of the various trees and diagrams.
Bill Dettmer call them “logical glue” that hold the trees together. In “The Logical Thinking Process”, Bill provides a full chapter (34 pages on the CLR).
There are eight Categories of Legitimate Reservation:
1. Clarity: is used to check the complete understanding of a word, idea or causal connection and avoid ambiguous wording. All the trees and diagrams are also good communication support, it is therefore important to insure the content is fully understood by anyone, even people not involved in the trees and diagrams construction.
2. Entity Existence verifies the reality or existence of the stated entity in the reality of the scope of analysis or problem solving. Sometimes people confuse building logical Thinking Processes trees and brainstorming, adding entities which are assumptions but not proven realities.
3. Causality Existence is the next thing to verify. Does the cause really lead to this effect? It is then important to read aloud the relationship, for example: “if A exist, then B exist” or “in order to have B, we must have A”.
4. Cause Sufficiency looks for one (set of) cause(s) to be sufficient by itself to create the effect. In complex systems, several independent causes could lead to the effect (logical OR) or some causes may combine to produce a given effect (logical AND).
If one legit cause remains hidden/unknown, the injections (solutions) may not always prevent the effect to occur. It is therefore important to list all causes.
5. Additional Cause is the check if no other cause, not mentioned so far, could have the same effect.
6. Cause-Effect Reversal checks the possible confusion between cause and effect.
7. Predicted Effect Existence is the search for an (additional expected and verifiable effect of a particular cause. Dettmer states that this reservation does not stand alone, but helps to validate or invalidate causality existence. If another predictable effect appears with this cause, the cause exists. If the additional effect does not show, the cause existence is very likely invalid.
8. Tautology, also called circular logic, is checking if the effect is not the sole and insufficient proof or rationale offered for the cause existence. It happens mostly when the cause is intangible: I strongly hopped for good weather ==> the weather was good because I strongly hopped for it.
Looking for “long arrows” is not formally part of the CLRs but I see it as such.
Long arrows are logical relationships linking causes to effects skipping multiple intermediate cause-and-effects, usually because the analysts know the intermediate links and do not feel necessary to describe them.
The risk of long arrows is to confuse people who weren’t involved in the tree building and/or are not sufficient familiar with the subject or situation.
Long arrows may also appear as flaws in the tree construction, thus making people reading them or attending a presentation doubt about the robustness and soundness of the whole.
The only acceptable long arrows, which are purposely used, are for Executive Summary Trees. And in this case, some caution is advised.