If you had to pick a single, underlying, unifying element that should govern everything you create, everything you manage, anything you attempt to improve, it would have to be the discipline of systems thinking.

Designing solutions, solving problems, resolving conflicts, managing constraints: at the core of each is the drill-down process of determining the cause-and-effect relationships between dependent, interconnected parts of an ordered whole.

It is about the system.

It is not about not the pieces or parts of the system--any of the parts, some of the parts, all of the parts independent of one another; it is not about a set of equally-important-yet-independent, related-yet-isolated measures; It is not about trying to improve everything about the system, all at the same time.

Every component of a development/production/improvement methodology--whether it is Lean Production, Six Sigma, Lean/SS, TQM, BPI, BPR, Theory of Constraints (TOC), or anything else--recognizes the need and importance of exposing cause-and-effect relationships in a system. But, the effort cannot acknowledge that need and importance, and then just declare victory.

Consider just one of the arenas in which the failure to rigorously expose cause-and-effect relationships plays out.

We routinely see management teams treat the symptom of a problem without bothering to address its root cause. We see these teams misinterpret the visible, undesirable effects of a problem for the problem, itself. We see them default to what they have predetermined to be the relationships between cause and effect, and accept those relationships at face value.

It is a failure to exercise legitimate reservations about what they see; it is a failure to ask questions that exhaust the possible errant explanations.


The most robust structures and categories for expressing, arguing, and challenging the existence and sufficiency of cause-and-effect relationships are found in the Theory of Constraints, in a set of tools known as logical thinking processes.

The structures referred to in the logical thinking processes are the logic trees: Current Reality Tree, Evaporating Cloud, Future Reality Tree, Prerequisite Tree, and Transition Tree. The categories referred to in the logical thinking processes are the so-called “proofs” known as the eight Categories of Legitimate Reservation:

  1. CLARITY means that there are not any misunderstandings or miscommunication about the situation; it clarifies the meaning of the statement, idea, or argument. Question: “Do I understand the problem? Really!?!” 
  2. ENTITY EXISTENCE is a reservation regarding the validity of a statement, idea, or argument. Question: “Does this situation exist? Really!?!” 
  3.  CAUSALITY EXISTENCE is a reservation about whether a stated cause leads to the stated effect.Entity Existence deals with the validity of the statement; Causality Existence deals with the connection between the statements. Question: “Does the relationship between cause and effect exist? Really!?!” 
  4.  CAUSE INSUFFICIENCY is a reflection of the fact that most effects are likely to have more than one cause. Question: “Can the stated cause result in the stated effect, completely on its own? Really!?! Does it require anything else? Really!?!” 
  5.  ADDITIONAL CAUSE is a reservation that there is another, independent cause of the problem. Cause Insufficiency is about “and”; Additional Cause is about “or”. Question: “Is there anything else that could have caused this to occur, completely on its own? Really!?!” 
  6.  CAUSE-EFFECT REVERSAL is based on the distinction between why something happens versus how we know that it happens. Is the stated cause really the source of the effect, or is the stated effect really the source of the cause. Question: “Do we have this completely backward? Is the effect actually the cause? Really!?!” 
  7.  PREDICTED EFFECT EXISTENCE is a substantiation tool. If the cause-and-effect statement is valid, then there should be an additional effect as a by-product; the existence of that additional predicted effect would prove the cause-and-effect statement; the absence would disprove it. Question: “Is there any other unavoidable outcome that corroborates the effect? Really!?!” 
  8.  TAUTOLOGY looks for circular logic, where the effect is offered as a rationale for the existence of the cause. Example: “We have even-flow production, that means we must have consistent cycle times. How do you know have consistent cycle times? Because we have even-flow production. Really!?!”

The rigor of relentless systems-thinking pays enormous dividends: designing the right solution and making the right decisions; solving the real problem instead of treating its symptoms; focusing the improvement effort on what is most important, right now; resolving conflicting ideas and objectives, without compromise; managing the constraint instead of managing everything.