If you've ever sought menswear advice from a dusty old book—or a dusty old dude—you've probably heard that a navy blazer goes with everything. That might be true, but we don't need a blazer that goes with everything—if it's cool enough for that, we'd rather wear a suit. What we can really use are trousers that go with everything. And as long as we're breaking fundamental rules of sartorialism, our vote is for wool pin- or chalk-stripe suit trousers, in a highly neutral navy or charcoal, without the matching coat. Wear with just about any sort of light-coloured dress shirt with an open collar and rolled up sleeves, or maybe with a cardigan or v-neck on top. Decent straight-leg, flat-front trousers like this are hard to find in the pants department, so look for them as suit separates, and don't be afraid to get something a little stodgy and take it to your tailor for streamlining. They're just pants, for chrissakes. Shown, left to right: J.Crew Aldridge suit pant ($175), in charcoal or navy Loro Piana wool. Lands' End tailored fit year-rounders ($70), charcoal only. Bonobos "Blue Lines" charcoal pants with blue pinstripes ($175).