How should they behave?

In August, the Business Roundtable,

which speaks for America's biggest companies,

from Amazon to JP Morgan Chase, provided a hint.

The group amended its two decade old declaration

that corporations exist principally

to serve their shareholders, to enshrine

a fundamental commitment to all of our stakeholders

- customers, employees, suppliers, communities,

and last in the list, investors.

What's driving this shift in corporate purpose?

The continuing attempt to restore trust in business,

badly damaged during the financial crisis.

Generational change, bringing new people

into the workforce with higher expectations,

and the technological tools to hold employers to account.

Consumer pressure, a renewed interest

in the investment opportunities in

environmental, social, and governance improvements.

And, cynics would say, companies desperate, self-interested

desire to avoid regulation and retain their licence

to operate.

Enthusiasts for companies with a positive purpose that

goes beyond profit are clear.

Companies that do not start paying more attention

to their own staff, the communities they serve,

and the environment as a whole, simply

will not survive to be the companies of the future.

Businesses that do adopt a broader purpose,

on the other hand, will benefit from the reinforced enthusiasm

and commitment of their employees and their customers.

But even the most environmentally

and socially friendly chief executive

has to generate enough of a return for the company's owners

to make it to that brighter horizon.

And managing the trade-offs necessary for the optimal

strategy is delicate.

Take a traditional oil and gas company.

If, as CEO, you move away from fossil fuels too soon,

investors will punish you, even as environmentalists applaud.

Move too late and your greener competitors

will steal a march on you in sustainable energy, as tougher

regulation penalises your core operations.

Critics point out, though, that purpose is hard to define,

let alone to measure.

And there are other obstacles in the way

of a permanent shift to a longer-term, purpose-led form

of capitalism.

Many asset managers and some asset owners

still seek short-term returns, and are rewarded accordingly.

National and regional differences in corporate

culture make it hard to apply a one-size-fits-all approach

without antagonising pure profit seekers in, say, the US,

or long-termists in Europe.

Then there's the threat of growing cynicism

if companies disappoint by falling

short of their lofty promises.

So could the trend towards a new corporate capitalism reverse,

as it did in the 1980s, when the postwar consensus

on the social responsibility of business

gave way to a harder-edged drive towards pure shareholder value?

It could.

But there are powerful forces working in favour of change.

Chief executives can, of course, still decide how seriously

to take these disruptive influences and act accordingly.

But they would be reckless if they ignored them.