So, how to bridge the gulf? To start, let’s look at the scientific studies. I turned up one from 1984 in which rats were injected with solutions of either cognac, scotch, tequila, vodka, or straight ethanol, and then observed for variations in motor impairment. The idea was that the test might reveal differences in the ways we’re affected by trace elements in liquor, called congeners. When a spirit comes out of a still, it’s never pure ethanol. Usually 10 or 20 percent consists of other ingredients, including fusel oils and acetaldehyde. The variation in congeners is why rum (which starts as sugar) doesn’t taste like whiskey (which starts as grain). But with the inebriated rats, no differences were observed in behavior or rectal temperature. (Don’t ask.) Of course, it’s hard to discern whether a rat given cognac was more melancholy than a rat who was given vodka.

Damaris Rohsenow, a professor of behavioral and social sciences at Brown University, pointed me to a few other studies, including one that suggested a high-congener spirit (bourbon, enhanced with quadruple the congeners) was more intoxicating than a low-­congener one (vodka). But since the researchers didn’t study un­enhanced bourbon, it’s not clear whether the observed difference would take place in the real world. Rohsenow also mentioned another study on liquor and mood, in which patients were given either bourbon or vodka while living at an inpatient lab for nine days. Researchers noted an increase in hostility, anxiety, and depression across the board. Yet there was no discernible difference between the bourbon and vodka drinkers.

And that’s about it, study-wise. Congeners may affect mood or behavior, but nobody has examined the matter very closely. “Studies are so expensive,” said Carlos Ruiz, a psychiatrist with the Florida Hospital Center for Behavioral Health, “and I don’t see their value, because, for example, we don’t have more tequila-related car accidents versus vodka-related ones.”

I did, however, hear a couple of plausible explanations for the persistence of the common wisdom. William Oswald, who founded the Summit Malibu Treatment Center, told me that even experienced drinkers may change their rate of consumption when they switch liquors. “If someone were to be a full-on whiskey drinker, he would know exactly how much he can drink without getting too polluted,” he said. “If he switches over to gin, it’s a different story.”

How the liquor is consumed is also crucial. If a drinker slams tequila back in shots, then he’ll get intoxicated faster than if he were gently sipping scotch. Presto: tequila gets a reputation. That leads to the issue of self-­fulfilling prophecy. If people believe tequila makes them rowdier, they may opt for tequila when they want to be rowdy.

So that’s where we are, until some benefactor funds a more conclusive study. Congeners may slightly alter mood or behavior. But more likely, we’re confusing cause and effect, and mood dictates your drink more than drink dictates your mood.