House-made bitters and fancy syrups have their place at the bar, but some nights they just seem like gratuitous pomp. Those nights call for a boilermaker, that separate-but-equal combination of a beer and a shot that takes its moniker from the nickname once given to industrial metalworkers — likely because neither plays around when it comes to getting the job done.

As times change, ideas evolve, and these days the shot in a boilermaker is no longer limited to whiskey. So what belongs side by side? There are a few theories for pairing spirits and beer, explains Evan Harrison, bar manager and co-owner of Cambridge’s State Park, which offers a handful of variations on the boilermaker theme.

First, there’s the origins approach: What grows together goes together, so to speak. A brawny Guinness is a logical accompaniment to an easy-drinking Irish whiskey, just as a light lager like Corona goes hand in hand with the concentrated earthiness of good tequila. Those combinations tell another story, one of contrast and balance.

Another methodology is to harmonize similar flavors, as Harrison does by pairing the Czech herbal liqueur Becherovka, heavy on baking spices, with cider. But these are just ideas, not rules. There’s no need to be precious about it. So go ahead and pour what suits your fancy.

“It’s not much of a commitment — it’s not like pairing dinner with a bottle of wine,’’ Harrison says. “It’s not a big deal — it’s still fun — if you mess it up.’’

Liza Weisstuch

Liza Weisstuch can be reached at liza.weisstuch@gmail.com. Follow her on Twitter @livingtheproof.