When SAT scores began to plummet at the end of the sixties—after rising steadily from 1945 until 1967—an easy explanation was that the trend was a reflection of the larger number of low-income students, many African Americans, who were beginning to take the tests. Then an education scholar noticed that the trend also applied in Iowa, where the proportion of blacks was small.    

In a terrific piece over at City Journal, E. D. Hirsch, Jr. traces the decline in SAT scores to a well-meaning concept of education that became dominant in the U.S. It downplayed the importance of factual knowledge and book learning in favor of training through hands-on experiences and optimism about a human being’s natural development.  These new theories were applied beginning in the 1950s.  

Cornel sociologist Donald Hayes demonstrated that the decline in SAT scores could be traced not to poverty but to the simplified learning brought about by the new theories. Since badly educated kids are less likely to grow up to get good jobs, this has profound economic significance. In fact, Hirsch notes, the size of one’s vocabulary is often a predictor of economic success:

[T]here’s a positive correlation between a student’s vocabulary size in grade 12, the likelihood that she will graduate from college, and her future level of income. The reason is clear: vocabulary size is a convenient proxy for a whole range of educational attainments and abilities—not just skill in reading, writing, listening, and speaking but also general knowledge of science, history, and the arts. If we want to reduce economic inequality in America, a good place to start is the language-arts classroom….

Such correlations between vocabulary size and life chances are as firm as any correlations in educational research. Of course, vocabulary isn’t perfectly correlated with knowledge. People with similar vocabulary sizes may vary significantly in their talent and in the depth of their understanding. Nonetheless, there’s no better index to accumulated knowledge and general competence than the size of a person’s vocabulary.

Simply put: knowing more words makes you smarter. And between 1962 and the present, a big segment of the American population began knowing fewer words, getting less smart, and becoming demonstrably less able to earn a high income.

What this means is that the United States could solve a lot of its employment problems and restore upward mobility—which is just another term for the American Dream, after all—by returning to the kind of book-based learning that was the norm before the 1950s. It may also indicate that you should sign on for one of my personal crusades: Bring back Latin!