Chief executives have been much derided during the past few months for detecting an abrupt loss of “visibility” in their businesses. Suddenly, they say, they can no longer predict what the revenues or earnings of their companies will be even a few months ahead.

For example, John Chambers of Cisco Systems said “visibility going forward is more difficult than we have ever seen”. John Roth of Nortel Networks said it was no longer possible to provide meaningful guidance for the company’s performance this year, “given the poor visibility into the duration and breadth of the economic downturn and its impact on overall market growth”. JDS Uniphase reported “a lower level of near-term sales visibility than the company has experienced in recent periods”.

The counter-argument, put by some of their more robust colleagues, is that these suddenly myopic business people can, in fact, see perfectly well - they just do not like what they see.

As an excuse, the loss of visibility probably ranks up there with Procter & Gamble’s unexpected discovery late last year that its business was held hostage by the state of the Turkish economy. Similar unsuspected interactions were spotted by those British companies that found vital supply routes were affected by the Kosovo air embargo.

Comes the hour, comes the excuse. Investors are probably right to be sceptical of the loss-of-visibility argument. It points nonetheless to a profound change in the relationship between big companies and their shareholders. This change took hold during the past decade of sustained economic expansion, which itself set the seal on nearly three decades of a global bull market.

Sustained economic expansion has bred an assumption that tomorrow will always be the same as today, plus a bit extra. During bull markets, investors can look like geniuses merely because their individual stock picks have been borne upwards by the underlying market trend. An implicit long position would always be validated, at least if it was properly diversified.

A similar factor has been at work in product markets. The sought-after “visibility” is the industrial equivalent of that stock-picker’s felicitous long position. Even if today’s revenues are a bit weak, tomorrow will see a satisfactory reversion to the long-term trend. And in recent memory that trend has always been upward.

It is when the belief in that ever-rising escalator crumbles that the lack of visibility sets in. Forecasts seem suddenly much riskier. It is not only that customers are delaying their orders until the last minute or - worse still - backing out of deals that once seemed certain. That would be bad enough. But the claim of loss of visibility also reflects an underlying queasiness that would have been familiar to any bewhiskered Victorian businessman.

In short, the cycle is back. Not for all industries yet, but certainly for some of the most glamorous. High technology, media, business capital goods - all the sectors that only 12 months ago could claim a manifest destiny of ever-rising demand - suddenly look weak. Weak enough, at any rate, to shatter the confident assumption of ever-rising revenues and profits.

If all that was at stake were the amour propre of a few chief executives, this would be no big deal. The problem is that all those years of steady prosperity have bred an assumption, among investors as well as managers, that in well run companies earnings never go down.

In the process, the much-vaunted alignment of interests of managers and shareholders has produced a form of executive compensation that gives chief executives a powerful incentive not to disagree.

What happens when the commitment of investors and managers to steady earnings growth runs headlong into a cyclical downturn?

Sometimes the results of a wilful determination to break free from cyclical thinking is good: top managers at Zeneca said the most positive outcome of their spin-off from ICI was that the cycle was no longer an acceptable excuse for poor results once the drugs business was separated from its heavily cyclical heavy chemicals sibling.

Sometimes it is bad, as when the desire to maintain earnings induces drastic cutbacks that damage long-term competitiveness.

And sometimes it is both good and bad, as in banking, where a desire to escape the interest rate cycle has produced a search for fee income (good) and a ratchet towards higher-return but riskier business at each turn of the cycle (bad).

It remains to be seen whether the commitment to non-cyclical earnings growth is a permanent shift of expectations or the temporary result of a 10-year economic expansion. In the meantime, sensible chief executives play for time - and declaring a loss of visibility is probably as sensible a way of doing that as any.