In short, languages are governed by trade-offs. One that avoids making certain information mandatory may be easy to speak, but leaves the listener to fill in the gaps. It may be simple to learn but less expressive. Some languages have lots of redundant elements: in los tres gatos negros están mojados (“the three black cats are wet” in Spanish), all six words indicate a plural. Marking the plural just once (as Chinese does) would be enough. But redundancy has a virtue: emphatic communication is more likely to survive a noisy environment.
Languages, Mr Dixon says, are like a Western-style house. There are a few rooms you must have (kitchen, bedroom, living room, bathroom), and some discretionary options (office, guest room). On a fixed budget, you can’t have all the extras. He does not crown a “best” language. In the end, he says, readers should make their own list of desirable features, and then closely examine a few languages to decide whether one has more of them than another. But the list of advantages, he concedes, is itself a matter of judgment. For all his scientific criteria, in the end the verdict is in the ear of the beholder.