I place significant emphasis on the way human beings rely upon language. We are talking animals, I argue. We live by and in language. We do what we do under certain descriptions. We articulate our reasons for what we do and ask others for their explanations and justifications. This all comes very naturally in the little everyday things of life and therefore, I argue, we need for our daily affairs easy access to a rich ordinary language. However, I claim, expertise and particularly the expertise about our behaviour, has somehow colonized our ordinary language. Expertise is replacing ordinary words by technical ones, sometimes even without our recognition. Think for instance of the teenager’s brain. We don’t know what is going on in there. Not anymore. That is for brain scientists to know. But as a consequence we don’t know what we are talking about when we are talking about our teenagers. We might want them to get out of bed in the morning, but they may claim that their brains are unsuited for getting up so early.

There is a further important theme relating expertise to language. In the technical domain experts develop smart interfaces between humans and equipment. Think about medication, microscopes, smartphones and self-driving cars. We don’t need to know how they work. We only need to know how to use them. But in the behavioural domain the only available interfaces are linguistic: instructions, procedures, communications. This raises a highly interesting new kind of problem, because it may be impossible for laypeople to use these linguistic devices when they don’t understand how they work, that is, what they mean. That, however, would require the laypeople to become experts, which, technically speaking, is a contradiction. I argue that there is an alternative: we might do without behavioural expertise if we develop and educate our common sense.