Last week, the Washington Post reported on a pair of studies released in January that further disprove an often-repeated theory that marijuana use is linked to lower intelligence. You might have heard that smoking marijuana makes you stupid. If you grew up in the '80s or '90s, that was more or less the take-home message of countless anti-drug PSAs. In more recent years, it's a message we've heard — albeit in more nuanced form — from Republican candidates on the campaign trail and from marijuana opponents…