Every like-chaser on Instagram – and that’s all of us, by the way – knows that pretty visuals are all very well, but that a great caption seals the deal. So it stands to reason that we should apply the same logic to our outfits. The best way to caption yourself? A slogan T-shirt.

Grownups didn’t use to wear slogan T-shirts, but now we do. There are, however, rules. Number one being: no jokes. Lols are almost never chic. My Auntie Went To Las Vegas And All I Got Was This Lousy T-Shirt stays in the painting-the-house pile. Rule two: keep it clean and above board. So no swearing, nothing saucy and keep it positive. (If you haven’t got anything nice to say, don’t say anything.)

That’s about as much as we can all agree on. Beyond that, it gets complicated. Example: you know that thing about how you shouldn’t wear a band or tour T-shirt if you can’t name three of their albums? Well, similarly, there are those who hold that you shouldn’t wear a T-shirt in a language you don’t speak. This position strikes me as unnecessarily draconian, but on the other hand it is a bit odd that much of the British high street now looks like the result of typing “feminism” into Google translate. Probably worth giving ourselves a quick reality check about the fact that two French words on your top doesn’t make you Carine Roitfeld, any more than namechecking feminism in your brunch look makes you Emmeline Pankhurst.

I hope that doesn’t sound mean, because I like these T-shirts. I can see nothing but goodness in the impulse to wear your heart on your sleeve or your values on your chest. And if it sounds more lyrical in French or looks better in the Russian alphabet, go for your life. But wearing a T-shirt isn’t the same as activism, and the fact that the new-gen slogan T-shirt is a less strident version of previous incarnations is reflected in how it is worn. If you were wearing your slogan as a statement, you’d team it with jeans and trainers, but since you’re wearing it as fashion, you team it with more elevated pieces and fabrics: with tailoring rather than jeans, with velvet instead of denim. Also, you might wear it half-underneath a jacket, so no one can read what it actually says. That’s not a problem, though. On the contrary, it adds a certain je ne sais quoi.

• Jess wears T-shirt, £85, bellafreud.com. Velvet blazer, £220, and trousers, £160, both boden.co.uk. Sandals, £140, senso.com.

Styling: Melanie Wilkinson. Hair and makeup: Samantha Cooper at Carol Hayes Management.