Aged 57, the American William Alexander set out to learn French. His engaging new memoir, Flirting with French, describes his year-long attempt. You come away from the book with an unfashionable question: for native English-speakers aged over 12, is it still worth investing the time to learn a language? The twin rise of global English and online translation engines has changed the cost-benefit analysis. 
Having spent much of my life trying to learn languages, I reckon there are four levels of mastery. The first is basic conversation: the ability to order dinner in German, for instance. Many people who study a language for years never get beyond this level. However, for anglophones this skill is becoming less useful. When I began learning German 30 years ago, many adult Germans couldn’t cope in basic English. Today, the tourist who stammers a few hard-earned German words is often answered in cheery English. This is increasingly true worldwide. English today is “more widely spoken and written, than any language has ever been”, wrote Robert McCrum et al in The Story of English. In addition, smartphone apps can now translate speech on the spot. Learning German (say) just for basic conversation probably isn’t worth the effort any more.
The second level of mastery is reading a language — perhaps not well enough to read Goethe but enough to understand a German newspaper. But this skill, too, is becoming obsolete. Online translation engines like Google Translate keep improving. Feed in a German article, and you’ll usually get a serviceable English version instantaneously. Google Translate isn’t quite Star Trek’s ‘Universal Translator’ yet but then neither are most human linguists. In short: don’t bother learning a language just for functional reading ability.
The third level of language mastery — high-level conversation — obviously remains useful. However, depending on the language, it can take years of work. Exotic languages can take Herculean effort. I once met an American who had spent seven years learning Mandarin Chinese. He said he regretted having done so, because he hadn’t got much beyond basic conversation. Crucially, most anglophones only start learning languages at school at about age 12 — exactly the age when the ability to learn languages is nosediving. Alexander quotes Michael Long, an expert at the University of Maryland, as saying that only a “tiny, tiny minority” of post-adolescent learners will attain near-native proficiency in another language.
After 12 years in Paris, I speak enough French to function at dinner parties and interview people. But I still sound even more boring and stupid in French than in English. The extra moment I take to process a sentence drains spontaneity from conversations. When a French person makes a joke, I panic.
In any case, viewed strictly in terms of narrow personal advantage, anglophones do best when speaking English to foreigners. That way we control the conversation, while they struggle and sound stupid. This helps us triumph in office politics, business deals and bar quarrels.
The truly useful level of linguistic mastery is perfect fluency. To me, this means being able to say and understand everything in a language, even if you have an accent and make grammatical errors. If you’re perfectly fluent, you can have long evenings nattering with close friends around kitchen tables. That’s the way to understand a country. The fluent Dutch I learnt in childhood has taken me into every room of the Dutch house. In France, I’ve never got beyond the salon.
To achieve perfect fluency, you need to start young — preferably as an infant. Anyone starting after age 12 probably won’t get far. Alexander admits, after 13 months studying French: “Not only have I failed to become fluent, or even conversant, in French, but I’ve failed spectacularly.”
Of course, studying a language has benefits besides actually learning the language. The learning process can also help you appreciate another culture (though probably not much if all you can say is “Zwei Bier, bitte”). Better, learning a language improves problem-solving and memory skills.

Put simply: bilingual kids are smarter. It even seems to work for older people. After Alexander’s year of study, he took a cognitive-functioning test. His scores — worrying a year before — had skyrocketed. The implications, he concludes, are “so startling, so important, I can almost overlook my failure to learn French”.
— Financial Times