I found the article rather confused. He begins by criticising the slogan as over-used, but by the end says that we do need to distinguish correlation from causation and the problem with the slogan is that it's just a slogan. His history of the idea ends in the 1940s, and he appears completely unaware of the work that has been done on this issue by Judea Pearl and others over the last twenty years -- unaware that there is indeed more, much more, than just a slogan. Even the basic idea of performing interventions to detect causality is missing. The same superficiality applies to the other issue he covers, of distinguishing statistical significance from importance.

I'd post a comment at the Slate article to that effect, but the comment button doesn't seem to do anything.

ETA: Googling /correlation causation/ doesn't easily bring the modern work to light either. The first hit is the Wikipedia article on the slogan, which actually does have a reference to Pearl, but only in passing. Second is the xkcd about correlation waggling its eyebrows suggestively, third is another superficial article on stats.org, fourth is a link to the Slate article, and fifth is the Slate article itself. Further down is RationalWiki's take on it, which briefly mentions interventions as the way to detect causality but I think not prominently enough. One has to get to the Wikipedia page on causality to find the meat of the matter.