## Causality, transitivity and correlation.

Disclaimer: Some not too structured thoughts. It’s commonly said that correlation does not imply causation. That is true (see Gwern’s analysis), but does causation imply correlation? Specifically, if “→” means causes and “~~” means correlates with, does X→Y imply X~~Y? It may seem obvious that the answer is yes, but it is not so clear. […]