Is the Theory of Constraints (TOC) a Theory?

By Jon Miller – August 18, 2007 10:52 PM

Is Lean a scientific theory? As a management system, Lean is
scientific in terms of the thinking process. Lean has been
experimentally verified in many cases over decades. The theoretical
premise, or basic hypothesis of Lean, can be stated as:

1. The customer defines value by what they are willing to pay for
2. Whatever is not value is waste
3. Eliminating waste reduces cost

Waste is specifically defined in the seven types (overproduction,
transportation, motion, inventory, defects, waiting, processing) as
well as safety losses, wasted space, energy losses and environmental
harm. If reducing inventory, defects or motion did not in fact reduce
cost, then this theory could be proven false.

It is worth noting that Taiichi Ohno, the person who is credited
with developing and advancing much of what is known today as Lean
management, often spoke out against TPS being a theory of any kind. The
words “practice, not theory” or “practical, not theoretical” were his
rejoinder to managers and professors alike who poked and prodded at the
workings of TPS. So perhaps “is Lean a scientific theory?” is the wrong

Lean appears to pass the test of falsifiability. But what about the
Theory of Constraints? The steps to managing through the Theory of
Constraints are:

0. Identify the goal (that which is being constrained)
1. Identify the constraint
2. Decide how to exploit the constraint
3. Subordinate all other processes to the constraint
4. Elevate the constraint
5. If the constraint has moved, return to Step 1

My concern here is that it appears to say in step 5 is “if the
Theory proves false, repeat the test until it is proven true”. Does TOC
admit the possibility that identifying and exploiting the constraint
and then subordinating all other to the constraint, and elevating the
constraint will fail to achieve the goal?


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