The great systems thinker Russell Ackoff had a provocation that stayed with me: A system isn’t the sum of its parts. It’s the product of their interactions.

He used a simple example. Take the best engine from one car, the best transmission from another, the best brakes from a third. You will not get the best car; you will get no car at all. The behavior lives in the interactions, not the parts.

That provocation raises a question: If optimizing parts is dangerous, what makes an optimization safe? In this article, I’ll begin with reversibility.

The problem with parts

The temptation is familiar. Something isn’t performing well. Fix it. Move on to the next thing. The assumption underneath is that a collection of locally optimized parts produces an optimized whole.

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