Since you seemed to like the correlation charts from yesterday, I figured I would give you one more related item.
When two events A and B are correlated (i.e. happen together), we can’t tell whether event A caused event B (rain caused me to bring my umbrella), event B caused event A (bringing my umbrella caused it to rain), or some event C caused both event A and event B (the existence of storm clouds caused both the rain and the umbrella-bringing). We point out a lot of situations where the real explanation is the think with the outside C event and relatively few with the “reverse causality” explanation, probably because a lot of the reverse causality scenarios don’t pass the sniff test of sanity. (I don’t like assuing things based on intuition, but even I would feel comfortable ruling out the possibility that bringing my umbrella caused it to rain.) Nonetheless, reverse causality is entirely possible, and even sort of has its own name:
Technically, these cases show both forward and reverse causality, resulting in various forms of unfortunate cycles. True reverse causality would be like that time in high school where my boyfriend’s parents told me I could eat whatever I wanted because I was skinny. Luckily for them (or not, in a way), I didn’t get on my correlation versus causation soapbox until years later.