A good decision is robust and insensitive to environmental changes.

A robust decision is a decision that remains correct even when the underlying assumptions used to arrive at that decision change. This means we have made a good decision even after things beyond our control change.

In practical terms this means we must, during our decision making process, identify our assumptions and ask ourselves how they influence our choices. We then have to look at how they may change and assess how that will affect our decision. If we find that our selected option is "best" for only a narrow range of assumptions, then we need to question its suitability and examine the other possibilities. At the very least, we have an awareness of the possible effects of changes and, perhaps, can work to prevent those changes from occurring.