Caveat: this is another “off the top of my mind” posts.
“Correlation is not causation” is a concept well familiar to all analysts – and to policy analysts in particular. It is so mainstream that it has its own wikipedia entry. The web is full of examples of weird correlations.
However, can we say that the absence of correlation indicates the absence of causation?
Certainly not: there might be other factors in place that affect a phenomenon and thereby “hide” the correlation.
At the same time, the absence of correlation is a much more reliable sign of the absence of causation, than its presence. It is much more likely that no correlation is confirmed (after more in depth analysis) as no causation, than correlation is confirmed as causation.
I would even say (as a rule of thumb) that the majority of non-correlations turns out to be non-causation, while the minority of correlations turns out to be causations.