There's no denying that speaking and thinking are closely related. We use words to convey ideas to other people, and to organize our own thoughts. We're so accustomed to giving verbal expression to our thoughts that it's easy to believe that we ‘think in words’. If language is so central to our thinking, then it seems only logical that the particular form of our language – the words that it has, the aspects of the world that it encodes grammatically, and so on – should have a powerful effect on how we think.

The suggestion that language influences thought has a long history, both inside and outside the field of linguistics. The idea is a compelling one; it's intriguing to contemplate the possibility that our minds are shaped in important ways by accidents of our native language. And not only is it a theoretically interesting idea, but if language really does affect thought, then the real-world consequences could be quite serious. Many people are concerned that politicians, advertisers, and others use language in manipulative and misleading ways. It's also been claimed that particular languages are well suited to certain purposes because of the kinds of thought they permit or encourage – or, on a more sinister note, that some languages prevent certain kinds of desirable thought, and therefore confine their speakers to a kind of mental straitjacket. If this is true, then maybe there are languages that deserve to be forgotten.

Unfortunately, the true nature of the relationship between language and thought turns out to be very difficult to study, and the history of thinking about this question is littered with questionable assertions, inaccurate claims, and just plain wild speculation presented as fact. But the good news is that a substantial body of rigorous experimental work on the topic has appeared in the last few decades. In this chapter, we'll look at popular ideas about the relationship between language and thought; then we will examine some relevant experiments, asking what the evidence says about whether, and to what degree, thought is shaped by language.

The Sapir-Whorf hypothesis

The idea that language influences thought is closely associated with Benjamin Lee Whorf, a linguist who worked in the first half of the twentieth century.