South Africa, June 15 -- Youth Month triggers a familiar cascade: statistics about unemployment, profiles of young founders, campaigns featuring people under 30. All of it was well-intentioned. Most of it is built on a premise that nobody has properly interrogated.

The premise is this: that youth is a demographic.

It is not. And the sooner the industry accepts that, the sooner it will start producing work that actually connects.

The definition problem

The marketing industry's own textbooks define the "youth market" as anyone between the ages of 11 and 35.

By that measure, a 34-year-old chief executive with a decade of business decisions behind her is still a youth marketing target.

A 22-year-old who has never left her hometown, has ...