I'm afraid that these authors have a somewhat blinkered understanding of what makes an expert. Rather than an academic knowledge, the knowing of expertise is organic and developmental, and may be developed over long periods of immersion in a mileu of a practice community. It is a deep knowledge of, or a need to find out and reflect upon the causes of things. He or she fits experience to practice, not practice to experience: practice is not shoehorned to fit preconceived ideas. The expert has a need to understand and question his or her practice, but also to work at the boundaries, the cutting edge of practice: asking the right questions is a feature and uncertainty is cherished. Expertise cannot be taught, for that would be to reify practice

Competing interests: None declared