Fast adoption, weak evidence
Marketing took to generative AI faster than most functions, and for good reasons: the work is text-heavy, the volume demand is real, and the cost of an individually mediocre output is usually low.
It is also the function least able to say whether it worked, and that is worth confronting at the start.
The reason is structural rather than a failure of rigour. Marketing outcomes are influenced by seasonality, competitor behaviour, pricing, product changes, macroeconomic conditions and the rest of the marketing mix, all moving at once. Attributing a change in results to a change in how the copy was produced is genuinely hard, and the existing lesson on the attribution problem covers why.
So the honest position is that most claimed AI marketing gains are unmeasured, and the confident ones are usually measuring output volume rather than outcome.
That has a specific consequence for this cursus. The useful question is rarely does AI improve marketing, which cannot be answered generally, but which specific tasks does it do adequately, at what cost, with what risk. Some of those answers are clear and favourable. Others are not, and the difference matters more than a general verdict.
The measurement discipline is the subject of the third lesson, and it is the part that separates a function that improved from one that produced more.

