The Economist has a Q&A with Geoffrey Nunberg in which the linguist discusses things he’s learned “by using big data techniques like Google’s Ngram viewer to analyse the word usage and track how language evolves”:
“Words don’t fly individually—they fly in flocks,” says Geoffrey Nunberg of the University of California Berkeley’s School of Information in an on-stage interview with Jeff Hammerbacher, a big-data engineer and the co-founder of Cloudera, during The Economist’s Ideas Economy: Information 2012 conference on June 5th in San Francisco (full video above).
As he explains it, society sees concepts emerge and dissipate over time, reflecting people’s views. So groups of words like “yuppie” and “sensitive type” and “sense of entitlement” all appear (and go out of favour) at roughly the same time, just as the dawn of the 19th century saw the birth of the “-isms” like liberalism and socialism and the rest.
For more on Ngrams, see this LH post.