Cause and Effect is itself an Effect of Systems of limited Complexity

Dettmer's The Logical Think Process (this will start to skip around a little)

"All systems operate in an environment of cause and effect." p 13

This is a statement of belief rather than an observation. There are many systems people have to deal with today where this is not true (cf Cynefin) and realizing when you are dealing with a system where it is true and when you are not is one of the keys of being able to take effective action.

Now it could be interpreted as: "in systems where cause and effect can be relied on, then TOC applies."

It could also be interpreted as saying: "yes, some systems are very complicated, but, in practice, it is most effective to reason about them "as if" they demonstrated cause and effect" which begs the question since if cause and effect in the system at hand are too complicated to discern, they cannot be used as a basis for judgment.

It is probably best to leave this as a tactical decision. If the system you are trying to reason about is at a level of simplicity where it demonstrates reliable cause and effect relationships...then assume cause and effect, if it is more complex, then you will be better to not base your reasoning on strict ideas of cause and effect.

I do not in any way think that realizing that cause and effect is not fundamental to all systems impacts the utility of the Theory of Constraints or reduces the efficacy of its methods. I think that it took an overly simplified view of reality (for very practical reasons) that can no longer be maintained in view of our current predicament. But the theory loses no power (in fact it may even gain in power) from "weakening" that assumption.