As the objection “correlation is not causation” has ankylosed into a thoughtless reflex, it has become a confusion generator. So it’s worth taking a step back:
… whilst it is true that correlation does not necessarily equate to causation, all causally related variables will be correlated. Thus correlation is always necessary (but not in and of itself sufficient) for establishing causation.
The claim that ‘correlation does not equal causation’ is therefore meaningless when used to counter the results of correlative studies in which specific causal inferences are being made, as the inferred pattern of causation necessarily supervenes upon correlation amongst variables. Whether the variables being considered are in actuality causally associated as per the inference is another matter entirely. …
Correlation is evidence. Causation is theory (and even, inevitably, ‘speculative’ theory).