Getting good advice?
When Croesus of Lydia considered going to war against the Persian Empire, he sought advice from the best available source of his day – the Oracle at Delphi. He was told that attacking the Persians would mean the end of a mighty empire. Armed with this “knowledge”, he attacked and a mighty empire, his own, was destroyed.
While the Oracle’s advice was arguably accurate, it definitely wasn’t helpful. The ambiguous answer conveyed more certainty than was warranted. While Croesus was complicit in his downfall (what’s that saying about “assumptions”?), the Oracle must also accept some blame. Failing to convey the uncertainty was a betrayal.
Just like Croesus, contemporary decision makers crave certainty. Executives are frequently called upon to synthesize multiple viewpoints, many of which may be outside their area of expertise, into a coherent decision. An expert’s opinion of what’s “right” can be a seductive thing. Likewise, technologists are often uncomfortable with ambiguity, and rightly so. Implementing contradictory requirements is difficult, to say the least.
Uncertainty, however, is a fact of life. Pretending that it does not exist is neither honest, nor effective. Picking a number without any basis in reality does not serve to eliminate it. In fact, elimination of uncertainty is a fool’s errand. As Tom Graves stated in “Who will lead us out of our uncertainty”:

But that tag-line is kinda interesting – because the only valid answer is ‘No-one’.
Oh, no doubt there’d be plenty of people who would offer to lead us out of uncertainty. Yet the reality is that in every case they’ll either be a fool, a fraud, or both. The blunt fact is that uncertainty is a fact of life: there is no way to ‘lead us out of uncertainty’ – because ‘certainty’ is itself a delusion about a world that does not and cannot ever actually exist.

A tweet from Charlie Alfred provides the alternative:

Just as weather is composed of many simple physical processes whose interplay results in a chaotic whole, so too are systems (both human and machine). While we may have a firm understanding of the behavior of the various components, as our scope widens, our certainty must decrease. Tweaks to those low-level components must be tempered by the knowledge that the consequences may go beyond our intentions.
Under these circumstances, the phrases “It depends” or “I don’t know” become the honest answer. It is important to remember, however, that Ruth Malan’s definition of a good architect, one who can tell you what it depends on, applies.
Given the uncontrolled variables of network speed, client machine capabilities, site traffic, and network traffic (just to name a few), anyone who guarantees a page load time for an internet application would be Tom’s “a fool, a fraud, or both”. The genuine article would explain why a definite answer was not possible, what actions could be taken to test the capability in question, and what could be done to improve the chances of meeting the requirement when faced with various challenges.
Human systems are just as chaotic and uncertain, subject to circumstances beyond an individuals control. Akio Toyoda, President of Toyota, was recently quoted in the New York times:

“Have we really turned into a company that will be profitable and continue to grow no matter what happens to its business environment?” he asked.
“I am not sure yet, is my honest answer. An unprecedented crisis even beyond the scale of the Lehman shock may happen again,” Mr. Toyoda added. “We’ll only know the answer when such events actually happen.”

It takes a certain amount of courage to say “I don’t know”. “It depends” is not always the answer that people want to hear. However, in the face of uncertainty, they are the right answers. Awareness of uncertainty arms you to deal with events as they arise. A false sense of certainty is comforting, right up until it’s shattered.
Re-posted from Form Follows Function