Outliers, impact, and rationalization in linguistic change

Quotative be like is a rapid global innovation, yet no evidence pinpoints when it arose, under what circumstances, or the consequences of its emergence. Using a data set spanning four cities and two hemispheres, we document systemic regularity across time and space. The results force us to confront three issues: the uniformitarian principle, the criterion of face-to-face contact in the diffusion of language change, and the nature of language as a complex adaptive system. Be like is an outlier, it has had a major impact on the linguistic system, and it can only be rationalized by hindsight, demonstrating the possibility of significant random events outside the predictable structures and processes in language. We conclude by suggesting that be like is a (linguistic) black swan event (Taleb 2010).