Causation vs. Correlation

Some may call it overused, some may say it is an important lesson, but either way, the phrase "Causation is not correlation," is applicable in many, many situations.

In fact, I would go to say that this is the most common logical fallacy people make. It comes up everywhere.

I do public forum debate, and for each topic, there will be one argument made at least once every round throughout the topic. For the January topic: "The cost of a college education outweighs the benefits," this argument was causation vs. correlation. In the over 25 rounds that I debated the topic, causation was brought up in every single one.

To be more specific, a common contention was that people who go to college make more money. The go to answer for this was, 'Our opponents have not proven a causal link, simply a correlation.' Now, this was in many cases true, people simply weren't bringing up evidence that had causality. Even though, in this instance, the causal link is rather fundamentally clear (degrees), it was still an important thing to point out to the judge in the debate round.

But more recently, namely the junior theme, I have found causation vs correlation to be a reoccurring issue in many of the arguments written or seen written. For example, for my question, "why is there increased public support for legalizing marijuana," one of my explanations has to do with an increase in positively shown pot on TV. It is true that notably more lax portrayals of marijuana increased with public support of legalization, but that is as far as one can conclusively tie together the two phenoms. It simply is impossible to find anything proving any sort of causal link.

And this isn't the only example I've come across in writing my junior theme, but to explain them all hear would make my paper redundant. To what extent have you encountered such a problem? To what extent do you think it is a common problem in general?