Multilingualism and manners

How do two multilingual people choose which language to use? If they both speak the same pair of languages, how do they choose which one to hold their conversation in? What are the social conventions?

The choice of language may be based on the dominant language of the place: they use whichever language most other people around them are speaking. 

It may be based on facility: their levels of proficiency in the two languages will be different. This means that one of them will have to speak in a language at which they are less adept than the other person. They use the language in which the gap between their respective levels is the smallest. 

It may be based on precedence: they’ve always used only one of their two available languages. Their relationship exists in one language, but not in the other. 

I live in Portugal and most of the people I speak with have Portuguese as a first language. When I begin talking, it’s obvious I’m not fluent in Portuguese: my accent is a bit off, or I use the perfect tense when it should be the imperfect, or I place my personal pronouns before the verb when they should go after.

This makes some people uneasy. They’re probably unsure how effective our communication will be. Or they’re worried that our exchange will take longer than it should. In such cases they often suggest switching to English. This may be a generous offer, a way to help. It may be their own pragmatic need to maintain and practise their English. It may be a default strategy: as soon as a stranger hesitates in Portuguese, switch to English. And occasionally it’s the desire to flaunt their skills. 

Having suggested a switch of languages, what are the social codes? What does it mean to remain obstinately in the starting language when the other speaker has already shifted?

I hardly ever switch. Speaking regularly is the only way for my Portuguese to improve. At work I mostly use English, so my day-to-day interactions outside of work are invaluable. Provided I’m speaking to a stranger, then I will obstinately persist in Portuguese, even if they are equally determined to stay in English. In some city centre shops and cafes, where the staff are used to tourists, this can mean a whole interaction in which I speak imperfect Portuguese and the other person replies in imperfect English. 

My selfish approach goes further. Sometimes English vs. Portuguese seems to be decided on the basis of first choice, best choice. As I approach someone who I know I'll need to talk to, I try to get the first word in, to launch the discussion in Portuguese in the hope it will stay there. 

Occasionally, though, I meet someone whose generosity pre-empts my selfishness. These rare and generous interlocutors ask at the start whether I would rather we used English or Portuguese. This pause before the exchange really gets started, this preparation of the meeting ground, requires a self-awareness and confidence. It requires being able to pause, think, martial your various resources and fit them to the situation. It's a very different skill to proficiency in this language or that. I am thankful.